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Oligochitosan: A plant diseases vaccine—A review
... It is derived from chitin, which is found in the shells of some crustaceans (shrimps, crabs, and squids), or fungi, and insects [22,23]. CS is a non-toxic, biocompatible, biodegradable polymer that exhibits special biological activities, such as antioxidant, anticancer [24], antibacterial [25][26][27], antifungal [28,29], immunity stimulation, and has the potential for use as a plantdisease control agent [25]. However, commercial CS often has a high molecular weight (Mw), which makes it difficult to dissolve at high concentrations in an acidic medium. ...
... It is derived from chitin, which is found in the shells of some crustaceans (shrimps, crabs, and squids), or fungi, and insects [22,23]. CS is a non-toxic, biocompatible, biodegradable polymer that exhibits special biological activities, such as antioxidant, anticancer [24], antibacterial [25][26][27], antifungal [28,29], immunity stimulation, and has the potential for use as a plantdisease control agent [25]. However, commercial CS often has a high molecular weight (Mw), which makes it difficult to dissolve at high concentrations in an acidic medium. ...
Chitosan (CS) samples with average molecular weight (Mw) of 80.4, 61.8, and 45.2 kDa were prepared by the heterogeneous degradation of CS using 1% H2O2 solution under ambient conditions. The degree of deacetylation (DD) of the resultant CS was almost unchanged compared with that of the original CS. The sulfur nanoparticles (SNPs) were prepared by acidification of sodium thiosulfate (Na2S2O3) in a CS-Cu²⁺ complex solution. The influence of Mw CS on the size of SNPs was investigated. The average size of the SNPs/CS-Cu²⁺ complexes measured through Transmission electron microscopy (TEM) images was 25.1, 32.3, and 48.3 nm for using CS with Mw of 80.4, 61.8, and 45.2 kDa, respectively. The obtained SNPs/CS-Cu²⁺ complexes were also characterized by Ultraviolet-visible (UV-Vis), Fourier-transform infrared (FTIR), and x-ray diffraction (XRD) measurements. The synthetic method is favorable for large-scale production. Furthermore, the SNPs/CS-Cu²⁺ complex can be used as an agent for controlling plant disease in agriculture.
... In the case of the antimicrobial activity of chitosan, this can occur directly because the polymeric chains (without any previous structural modification) can interact directly with the cell wall of microorganisms, generating a breakdown or lysis of these structures, causing the loss of protein compounds and other intracellular constituents (Ayala, 2015;Hemantaranjan, 2014;Xing et al., 2014). On the other hand, plant strengthening, plant eliciting, plant growth promotion, and plant immunity regulation are probably exerted by chitinous oligomeric structures produced by the enzymatic degradation of initially polymeric chitinous materials (Eckardt, 2008;Gubaeva et al., 2018;Hadwiger et al., 1994;Hayafune et al., 2014;Iriti & Faoro, 2009;Kaku et al., 2006;Li et al., 2020;Petutschnig et al., 2010;Vander et al., 1998;Yin et al., 2010). In nature, this degradation occurs in situ by the action of chitinases, chitosanases, and chitinosanase present or induced in plant cells . ...
... Another example of how a specific structural configuration has higher biological activity than others is the highest priming activity induced by the ADDD* monoacetylated tetramer in rice cells versus its counterparts DADD*, DDAD*, and DDDA* (* denote a reducing end group) . The biological activity induced by chitinous oligomers in plants has been described, but the limited knowledge about specific signaling receptors and plant mechanisms to transduce the signaling induced by chitinous oligomers has prevented the identification of the molecular structures that trigger the highest biological activity in each plant species (Li et al., 2020;Yin et al., 2010). ...
Chitinous materials (chitin and its derivatives) are obtained from renewable sources, mainly shellfish waste, having a great potential for the development of bioproducts as alternatives to synthetic agrochemicals. Recent studies have provided evidence that the use of these biopolymers can help control postharvest diseases, increase the content of nutrients available to plants, and elicit positive metabolic changes that lead to higher plant resistance against pathogens. However, agrochemicals are still widely and intensively used in agriculture. This perspective addresses the gap in knowledge and innovation to make bioproducts based on chitinous materials more competitive in the market. It also provides the readers with background to understand why these products are scarcely used and the aspects that need to be considered to increase their use. Finally, information on the development and commercialization of agricultural bioproducts containing chitin or its derivatives in the Chilean market is also provided.
... COS has been proved versatile for agricultural purposes [11][12][13][14][15][16][17][18][19]. For example, COS was reported to be effective on yield, components, and crop production [12,13]. ...
... As a natural bioactive elicitor, COS has been largely investigated for its physiological function such as stimulating seed germination [14], improving chlorophyll and soluble sugar contents [15,16], enhancing the activities of antioxidant enzymes [17,18], and inducing salt and drought tolerance [15,18]. Additionally, COS has been reviewed for its function as a plant disease vaccine [19]. ...
Chitosan oligosaccharides (COS) has been abundantly studied for its application on regulating plant growth of many horticultural and agricultural crops. We presented here the effect of COS on tea plant growth and yield by physiological and transcriptomic checking. The results showed that COS treatment can enhance the antioxidant activity of superoxide dismutase (SOD) and peroxidase (POD) and increase the content of chlorophyll and soluble sugar in tea plants. The field trail results show that COS treatment can increase tea buds’ density by 13.81–23.16%, the weight of 100 buds by 15.94–18.15%, and the yield by 14.22–21.08%. Transcriptome analysis found 5409 COS-responsive differentially expressed genes (DEGs), including 3149 up-regulated and 2260 down-regulated genes, and concluded the possible metabolism pathway that responsible for COS promoting tea plant growth. Our results provided fundamental information for better understanding the molecular mechanisms for COS’s acting on tea plant growth and yield promotion and offer academic support for its practical application in tea plant.
... The biomedical and industrial benefits of oligochitosan (a cationic oligoelectrolyte) are examples of this. 14,17,[22][23][24][25] Grinberg et al. found that the complexes between b-lactoglobulin and oligochitosan were stable and primarily driven by enthalpy, with a high affinity constant. The authors also reported that the complexation induces changes in the protein structure: at low oligochitosan concentration, the b-lactoglobulin tertiary structure is destabilized. ...
In this study, we conducted a comprehensive computational investigation of the interaction between α-lactalbumin, a small globular protein, and strong anionic oligoelectrolyte chains with a polymerization degree from 2 to...
... There is one more piece of evidence that the Ca 2+ concentration in the cytoplasm is a regulator of plant defense against TMV. It has been shown that polysaccharides may act as elicitors of the plant immune system by triggering Ca 2+ influx into the cytoplasm, which presumably regulates calreticulin activity as well as ROS and SA production (Menard et al., 2004;Yin et al., 2010;Zhao et al., 2018). ...
Calcium is a universal messenger in different kingdoms of living organisms, regulating most physiological processes including the defense against pathogens. The threat of human viral infections became very clear in the recent years, which obviously triggered detailed research of all aspects of host-virus interactions, including the suppression of calcium signaling in infected cells. At the same time however, the threat of plant viral infections is underestimated in society, and research in the field of calcium signaling during viral infections is scarce. Here we highlight an emerging role of calcium signaling for the antiviral protection in plants in parallel with the known evidence for animal cells. Obtaining more knowledge in this domain might open new perspectives for future crop protection and improvement of food security.
... However, these responses are highly complex, and they are conditioned by various chitosan-based structures and concentrations, as well as by plant species and stage of development [94]. According to Yin et al. [95], oligochitosan is a potential plant vaccine, and its effectiveness is comparable with vaccines that have been developed for human and animal use [96]. ...
Biostimulants are becoming more prevalent in the production of forage and turfgrasses. Many can be classified as natural biostimulants, including humic acids (HA), fulvic acids (FA), protein hydrolysates (PHs) and seaweed extracts (SWE), in addition to chitosan, silicon, inorganic compounds, beneficial fungi, bacteria and synthetic biostimulants. The article reviews recent research on the effects of biostimulants in the cultivation of forage grasses (perennial ryegrass, annual ryegrass, Festulolium, Kentucky bluegrass, annual bluegrass, orchard grass and timothy-grass) and turfgrasses (perennial ryegrass, Kentucky bluegrass, tall fescue, red fescue and creeping bentgrass). Literature analysis suggests that biostimulants enhance the quality of grasses, augment their tolerance to environmental stresses, facilitate nutrient uptake and improve the visual aspect of grasses. While biostimulants cannot replace fertilisers, they can significantly improve crop effectiveness in utilising the nutrients present in the fertilisers. This paper also briefly describes the legal and regulatory status of biostimulants with a focus on the EU and PL.
... Polysaccharide immunity inducers, such as amino oligosaccharides, CTS, chitin and LNT, have been widely used in controlling plant virus diseases (Zhao et al., 2007). LNT, as a biological polysaccharide, has multiple functions that confer disease resistance, such as closing plant stomata, inducing the expression of plant resistance genes and improving plant defence-related enzyme activity, such as superoxide dismutase (SOD), peroxidase (POD) and catalase (CAT) (Sun et al., 2022;Yin et al., 2010;Zhao et al., 2007). ...
Control of plant virus diseases largely depends on the induced plant defence achieved by the external application of synthetic chemical inducers with the ability to modify defence-signalling pathways. However, most of the molecular mechanisms underlying these chemical inducers remain unknown. Here, we developed a chitosan-coated lentinan-loaded hydrogel and discovered how it protects plants from different virus infections. The hydrogel was synthesized by coating chitosan on the surface of the calcium alginate-lentinan (LNT) hydrogel (SL-gel) to form a CSL-gel. CSL-gels exhibit the capacity to prolong the stable release of lentinan and promote Ca 2+ release. Application of CSL-gels on the root of plants induces broad-spectrum resistance against plant viruses (TMV, TRV, PVX and TuMV). RNA-seq analysis identified that Nicotiana benthamiana calmodulin-like protein gene 3 (NbCML3) is upregulated by the sustained release of Ca 2+ from the CSL-gel, and silencing and overexpression of NbCML alter the susceptibility and resistance of tobacco to TMV. Our findings provide evidence that this novel and synthetic CSL-gel strongly inhibits the infection of plant viruses by the sustainable release of LNT and Ca 2+. This study uncovers a novel mode of action by which CSL-gels trigger NbCML3 expression through the stable and sustained release of Ca 2+ .
... Wang et al. [60] proposed that primary metabolites induced by oligochitosan behave as the source of energy and signaling or as substrate molecules that have indirect or direct roles in defense reactions against Geotrichum candidum, also known as sour rot, in citrus fruit. Oligochitosan, obtained from chitosan, is a potential plant immunity regul [45,46]. It has shown an extensive range of biological applications, including as a p growth stimulator, antimicrobial agent, and feed additive, among others [47,48]. ...
Chitosan is illustrated in research as a stimulant of plant tolerance and resistance that promotes natural defense mechanisms against biotic and abiotic stressors, and its use may lessen the amount of agrochemicals utilized in agriculture. Recent literature reports indicate the high efficacy of soil or foliar usage of chitin and chitosan in the promotion of plant growth and the induction of secondary metabolites biosynthesis in various species, such as Artemisia annua, Curcuma longa, Dracocephalum kotschyi, Catharanthus roseus, Fragaria × ananassa, Ginkgo biloba, Iberis amara, Isatis tinctoria, Melissa officinalis, Mentha piperita, Ocimum basilicum, Origanum vulgare ssp. Hirtum, Psammosilene tunicoides, Salvia officinalis, Satureja isophylla, Stevia rebaudiana, and Sylibum marianum, among others. This work focuses on the outstanding scientific contributions to the field of the production and quality of aromatic and medicinal plants, based on the different functions of chitosan and chitin in sustainable crop production. The application of chitosan can lead to increased medicinal plant production and protects plants against harmful microorganisms. The effectiveness of chitin and chitosan is also due to the low concentration required, low cost, and environmental safety. On the basis of showing such considerable characteristics, there is increasing attention on the application of chitin and chitosan biopolymers in horticulture and agriculture productions.
... Poly-and oligomers of variable, controlled sizes are used in the food, cosmetic, medical and agricultural sectors" [18]. "The physiological effects of chitosan oligomers in plants are the results of the capacity of its polycationic compound to bind a wide range of cellular components, including DNA, plasma membrane and cell wall constituents, but also to bind specific receptors involved in defence gene activation, in a similar way as plant defence elicitors" [19][20][21][22]. ...
In recent days, several technological innovations were proposed in order to improve the production and sustainability through a significant reduction in use of agrochemicals. One 0f the best approach to increase crop productivity is the utilisation of environment-friendly organic products such as “Biostimulants”. There are different types of substances that act as biostimulants namely humic and fulvic acid, protein hydrolysates and other N-containing compounds, Seaweed extract and botanicals, Chitosan and other biopolymers, Inorganic compounds, beneficial fungi and bacteria. These biostimulants plays an important role in improving the plant growth, yield and quality of the product. The guava fruits coated with chitosan 1% and stored at 12°C had shown higher firmness, TSS, titratable acidity and maintained greenness with a slow increase in yellow colour by the end of storage. Knowledge on effective use of these biostimulants by understanding their properties has become a challenge to the researchers to improve yield, quality and shelf life of different horticultural products.
... For example, rice straw, corn straw, corncob, and wheat straw can serve as raw materials for the production of oligosaccharides within the biorefinery framework along with the production of biofuels [34,35]. In addition to being used as feed additives, oligosaccharides can also be used as fertilizer and plant disease vaccines [36]. At present, functional oligosaccharides are extracted from crop straw, mainly wheat straw [37]. ...
We conducted an 8-week feeding trial to investigate the effect of mixed functional oligosaccharides (chitosan oligosaccharide, fructooligosaccharide, and xylooligosaccharide) extracted from wheat straw on the growth, feeding, physiology, histology, muscle texture, and gut microbiota of Micropterus salmoides. Six diets were formulated by incrementally adding mixed functional oligosaccharides (0.1, 0.5, 1.0, 1.5, and 2.0 mg/kg) to the control diet. 30 individuals with initial body weight of 25.1 ± 3.5 g were randomly allocated to 6 triplicate tanks and fed to apparent satiation twice daily. The fish fed 1.0 mg/kg additives displayed maximum growth, and the feed conversion ratio decreased with the increase in additives from 0 to 1.0 mg/kg ( P < 0.05 ) but did not decline further with the addition of more than 1.0 mg/kg ( P > 0.05 ). The villus height and width were significantly higher in the supplementation groups than in the control group, while the gut and liver structures presented abnormalities with excessive supplementation above 1.5 mg/kg. There were significant differences in muscle texture indices for M. salmoides over the fed additive gradient, and the hardness, gumminess, and chewiness were highest in the 1.0 mg/kg group. High oligosaccharide levels, such as 2.0 mg/kg, decreased the LZM level, while there were no significant differences in the SOD and MDA levels. Gut microbiome analysis revealed no significant differences in richness and diversity for groups fed the functional oligosaccharide gradient; however, the PCoA results showed that the microbial community composition changed markedly in response to different addition levels, and the 0.5 and 1.0 mg/kg supplementation groups were far apart from the lower and higher supplementation groups. The relative abundance of Proteobacteria was lower in the 0.5 and 1.0 mg/kg addition groups, while that of the phyla Fusobacteria and Firmicutes were higher in these two groups. Functional classification showed that microbes related to carbohydrate metabolism were more abundant in the 0.5 and 1.5 mg/kg groups than in the other groups.
... 65,66 The plant diseases vaccine such as oligochitosan, which is effective at eliciting plant innate immunity against plant diseases, is a fascinating research direction. 67 The transgenic sugar beet has significant potential and commercial value for CLS control. The resistance can be acquired by the expression of transgenes that encode detoxifying enzymes, anti-fungal peptides and phytoalexins. ...
Leaf spot disease caused by Cercospora beticola Sacc. is the most damaging foliar disease threatening sugar beet production worldwide. The wide spread of disease incurs a reduction of yield and economic losses. The in-depth knowledge of disease epidemiology and virulence factor of pathogen is crucial and basic for preventing fungal disease. The integrated control strategies are needed for an efficient and sustainable disease management. The rotation of fungicides and crop could reduce the initial inoculum and delay the emergence of resistant pathogens. Spraying fungicides under the guide of forecasting models and molecular detecting techniques may hinder the onset of disease prevalence. The resistant varieties of sugar beet to cercospora leaf spot could be obtained by combining classical and molecular breeding methods. More effective approaches are supposed to develop for prevention and control for fungal disease of sugar beet.
... Oligochitosan is an alternative plant supplement which acts as an elicitor that is proven to be very effective in controlling disease infections and improving yield productivity (Yin et al., 2010). It is derived from the degradation of chitosan using gamma radiation. ...
Brassica juncea is one the most popular vegetables cultivated in Malaysia. The effects of M99 biofertilizer and oligochitosan in increasing nitrogen use efficiency (NUE) in Brassica juncea (mustard) was investigated. Biofertilizer is a mixture of microbes containing major nutrient-providing microorganisms. Oligochitosan on the other hand acts as an elicitor that has been proven to be very effective in controlling disease infections and improving crop productivity. Five treatments namely control (C), farmers practice (FP), biofertilizer (B), oligochitosan (O) and biofertilizer with oligochitosan (BO) were applied on the plants. For FP treatment, nitrogen, phosphorus and potassium (NPK) fertilizer were used. All of the treatments were applied onto plants at week three and four after sowing. In addition to NUE, data on plant yield in tonne per hectare was also collected. From this study, highest NUE (20.02%) was obtained through BO treatment whilst FP treatment was observed to produce the highest yield (40.22%) among other treatments. From this finding, combination of BO and FP applications are suggested to be used. However further investigation is needed in order to see the effect on yield and efficient use of plant nutrients.
... CHT und seine Derivate erhöhen den Glucanasegehalt und die Aktivität in Reis, Weizen, Tabak usw. [219][220][221]. Es wird auch berichtet, dass CHT und seine Derivate die Aktivität von Chitinase, Peroxidase, Phenylalanin-Ammoniak-Lyase, Polyphenoloxidase, Superoxid-Dismutase und Katalase in Weizen, Gurke, Tomate, Süßkirsche, Tafeltraube, Birne, Orange, Erdbeere, Zanthoxylum bungeanum und Ginseng erhöhen [194,196,[222][223][224][225]. ...
Zusammenfassung: Das Biopolymer Chitosan (CHT) ist ein de-acetyliertes Chitinderivat, das in der äußeren Schale von Garnelen, Schalentieren, Hummern oder Krebsen sowie in den Zellwänden von Pilzen vorkommt. Aufgrund seiner biologischen Abbaubarkeit, seiner Ungiftigkeit für die Umwelt und seiner Biokompatibilität ist es eine ideale Ressource für die nachhaltige Landwirtschaft. Das CHT entpuppte sich als vielversprechendes Mittel, das als Pflanzenwachstumsförderer und auch als antimikrobielles Mittel eingesetzt wird. Es induziert das Pflanzenwachstum durch die Beeinflussung pflanzenphysiologischer Prozesse wie Nährstoffaufnahme, Zellteilung, Zelldehnung, enzymatische Aktivierung und Proteinsynthese, was letztendlich zu einer Ertragssteigerung führen kann. Es wirkt auch als Katalysator, um das Wachstum von Pflanzenpathogenen zu hemmen und die Abwehrreaktionen der Pflanze zu verändern, indem es mehrere nützliche Stoffwechselwege auslöst. Diese Übersichtsarbeit hebt die Rolle und die Mechanismen von CHT als Pflanzenwachstumsförderer und Krankheitsunterdrücker hervor, sowie seine zukünftigen Auswirkungen in der Landwirtschaft.
... To ensure plant survival and growth-defense balance, the levels of JA and its bioactive form JA-Ile, and ABA up-regulate the expression of wound-inducible genes, including those encoding proteinase inhibitor II (PI2) and enzymes involved in the production of defense compounds, such as flavonoids and terpenoid indole alkaloids (Peña-Cortés et al. 1995;Dammann et al. 1997;Kang et al. 2021). The poly-cationic ability of Ch allows the binding to a wide range of cellular components (i.e DNA, plasma membrane, and cell wall components) and specific receptors involved in defense gene activation similar to plant defense elicitors (Yin et al. 2010;Hadwiger 2013;Katiyar et al. 2015). Ch binding to specific cellular receptors, hydrogen peroxide accumulation, and Ca 2+ leakage have been demonstrated at cellular level, causing thereby significant physiological changes, as they are key players in stress response signaling and developmental regulation (Povero et al. 2011;Ferri et al. 2014). ...
The FAO estimates a 34% increase in the world population by 2050. As a result, the productivity of important staple crops needs to be boosted by ca. 43%. Against the mosaic of global climate change and shifting arable land ranges, plant and soil sciences play a primordial role in finding solutions to the internationally shared challenges of ensuring sustainable agricultural and biomass production. However, to effectively meet these challenges and demands, knowledge obtained from essential plant and soil sciences must be connected to innovative applications in agriculture and plant cultivation. Particularly with the increase and severity of abiotic stresses such as drought, salinity, soil organic matter, nutrient poverty, heavy metals, extreme temperatures, and floods. Hence, sustainable biological practices such as biostimulants that boost plant yield, quality or even novel functionality, and tolerance to abiotic stresses should be exploited to improve agricultural production. Thus, the biostimulants segment is very promising with a growth rate of over 12%. This effervescence explains the growing interest of scientists and industrialists to find new sources of plant biostimulants targeting specific agronomic needs. This review focuses on (i) the impact of abiotic stresses on crop growth and tolerance and their response mechanisms, (ii) the main categories of biostimulants (compost, humic substances, protein hydrolysate, seaweed extract, chitosan, inorganic compounds, and microorganisms (i.e. endophytes, AMF, and PGPR)), (iii) the application methods and mode/mechanisms action of biostimulants, (iv) mechanisms of plant tolerance by microbes in interaction with organic and inorganic fertilizers, and (v) the main constraints noted limiting the use of biostimulants.
... The field test was conducted using the rape crop cultivation technology common for Central Chernozem region [12][13]. Environmentally friendly (nano) chips with elicitors (chitosan) introduced into their composition were used during the testing [14][15][16]. The crop was sprayed with biopesticides (chitosan) in the phases of 4-6 leaves and budding -flowering. ...
This particular study deals with the impact of pre-sowing nanotube-based seed treatment technology on rapeseed (Brassica napus) growth and yield. During the field tests we identified a significant yield increase as a result of applying the pre-sowing nanotube-based seed treatment technology. The main treatment agents were physiologically active nanochips consisting of carrier matrix nanotubes with eliciting activity ("Taunit", "Taunit-M", "Taunit-MD", and graphene). Enriching nanochips with insecticide-fungicide Kruyzer for guaranteed seed protection from crucifer flea allowed to raise the yield up to 8.08 t / ha - 12.28 t / ha.
... The ·OH has high activity and strong oxidation, which can intensify the chemical reaction process such as synthesis of chemicals, degradation of the water pollutants, etc. [9] Low molecular weight chitosan (LMWC) [10,11] is the degradation product of high molecular weight chitosan (HMWC). Compared with the HMWC, LMWC has better solubility and superior functional properties such as anticancer activity [12], antifungal activity [13], enhancing immunity [14], disease resistance [15], etc. HC is a green technology that can be used to enhance the degradation of chitosan (CS) to obtain LMWC, which has attracted the attention of more and more scholars in recent years [16][17][18][19]. The degradation of CS is mainly caused by the mechanical effect and chemical effect (free radical effect) produced during the cavitation bubble collapse [20]. ...
Hydroxyl radical (·OH) is a key component that leads to the cleavage of the glycosidic bond in the process of chitosan (CS) degradation by hydrodynamic cavitation (HC). In this paper, methylene blue (MB) was selected as the trapping agent of ·OH and the yield of ·OH in an impact-jet hydraulic cavitator was investigated. The results showed that the cavitation intensity and the number of passes (N) were the two main factors affecting the yield of ·OH. A smaller cavitation number (Cv) or a larger N indicated that more ·OH can be produced. Based on the dimensionless number correlation method, the yield of ·OH was correlated with Cv, N, Euler number (Eu), Reynolds number (Re), and a dimensionless parameter (γ), and a prediction model of ·OH yield was established. The relative deviations between the experimental and calculated values of the ·OH yield were basically within 10% by the prediction model. On the basis of the prediction model, the yield of ·OH produced in the process of CS degradation by HC was obtained. The results showed that the predicted yield of ·OH was significantly correlated with the intrinsic viscosity reduction rate of CS. It was suggested that the prediction model of ·OH yield based on the MB solution can be used to calculate the ·OH yield during the degradation of low concentration CS by HC.
... Various reports suggest that chitosan itself is effective in triggering plant innate immunity by showing low degree of symptom severity 79 . Scientists have affirmed that treatment with chitosan and its nano-derivatives could significantly enhance disease resistance among seedlings during germination stages 80 . Moreover, metallic conjugates of nanochitosan could further improve the disease resistance capacity as evaluated from disease incidence attribute of our study. ...
Agro-researchers are endlessly trying to derive a potential biomolecule having antifungal properties in order to replace the application of synthetic fungicides on agricultural fields. Rot disease often caused by Fusarium solani made severe loss of wheat crops every year. Chitosan and its metallic nano-derivatives hold a broad-spectrum antifungal property. Our interdisciplinary study deals with the application of nickel chitosan nanoconjugate (NiCNC) against Fusarium rot of wheat, in comparison with chitosan nanoparticles (CNPs) and commercial fungicide Mancozeb. CNPs and NiCNC were characterized on the basis of UV–Vis spectrophotometry, HR-TEM, FESEM, EDXS and FT-IR. Both CNPs and NiCNC were found effective against the fungal growth, of which NiCNC at 0.04 mg/mL showed complete termination of F. solani grown in suitable medium. Ultrastructural analysis of F. solani conidia treated with NiCNC revealed pronounced damages and disruption of the membrane surface. Fluorescence microscopic study revealed generation of oxidative stress in the fungal system upon NiCNC exposure. Moreover, NiCNC showed reduction in rot disease incidence by 83.33% of wheat seedlings which was further confirmed through the observation of anatomical sections of the stem. NiCNC application helps the seedling to overcome the adverse effect of pathogen, which was evaluated through stress indices attributes.
... The action of the secondary metabolites is inevitable in the plant protection function. Among the secondary metabolites, the role of phenolic compounds is considered to be the most important as they are the natural defense mediators in plants and elicitor the plant's innate immune response [18]. Phenolic compounds like flavonoids provide resistance against pathogens by acting as feeding deterrents. ...
Several strategies have been developed to control the diseases in plants however, the majority of them use chemical fungicides and pesticides. These agrochemicals have been in use for several decades to control various plant diseases. The widespread usage of agrochemicals has certainly decreased the outbreak of diseases, but at the same time has contributed to the development of resistance in pathogenic organisms. The emergence of resistant pathogens, the ever-increasing demand for crop productivity, and dwindling farmlands due to the explosion of the population have forced researchers to develop new, effective and inexpensive antimicrobial agrochemicals that are less likely to stimulate resistance in pathogenic organisms. The implications of chemical fungicides and pesticides in soil and water pollution have also mandated the search for alternative approaches to disease control management in plants. Chitosan, are deacetylated derivatives of chitin - a natural nontoxic polymer derived from the skeletal material of crustacean's shells and fungal cell walls. As nanotechnology has evolved as a promising field, the Chitosan-based nanoparticles have been considered one of the promising disease controlling agents and immune boosters in plants owing to their unique chemical and physical properties which increase the contact and permeability in cells. Its cationic nature, biodegradable, biocompatible, and antimicrobial properties make it a suitable candidate in the field of agriculture. Chitosan nanoparticles possess several agricultural applications including seedling growth and development, efficient nutrient usage, plant growth, antimicrobial activity, disease control, and elicitors of plant defense mechanisms. Chitosan nanoparticles have been evaluated as a potent inducer of antioxidant and defense enzymes in plants. Increased levels of defense responses due to the higher expression of defense-related genes have been recorded in transcriptome analysis of plants treated with chitosan nanoparticles. This present chapter documents the possible applications and mechanisms of chitosan nanoparticles to induce and augment immune responses in plants.
... The oligochitosan is an interesting representative of chitosans of low-molecular weight (~10 kDa). It has attracted increasing interest due to its important biomedical and industrial advantages (Blagodatskikh et al., 2018;Chae, Jang, & Nah, 2005;Muzzarelli & Muzzarelli, 2005;Yin, Zhao, & Du, 2010). The higher solubility and lower solution viscosity of the oligochitosan are beneficial for its processing and preparation of functional compositions. ...
β-lactoglobulin–oligochitosan (MW 9500 Da) system was studied under conditions of protein-polysaccharide incompatibility, the dipole-charge, and charge-charge protein-polysaccharide interactions at pH 3.0, 5.5, and 6.0, respectively, using ITC, DSC, and DLS. At pH 5.5 and 6.0, the ITC data revealed a complex formation between β-lactoglobulin and oligochitosan. The binding curves of the protein to the polysaccharide were obtained. The binding parameters, namely, the number of sites (n) and the binding constant (Kb), were estimated in terms of the Langmuir equation. These are n= 2.8 ± 0.1 and Kb = 106.4±0.1 M⁻¹ at рН 5.5, while n= 1.5 ± 0.1 and Kb = 105.6±0.1 M⁻¹ at рН 6.0. At pH 3.0, when both the protein and polysaccharide are positively charged, the denaturation parameters of β-lactoglobulin in the β-lactoglobulin–oligochitosan system and in the absence of the polysaccharide coincide independently of the system composition. Under conditions of the complexation, the denaturation parameters of β-lactoglobulin (the denaturation temperature, enthalpy, entropy, and width) displayed complicated dependences on the oligochitosan content. Their analysis supported by measurements of the diffusion coefficients implied that the conformational stability of β-lactoglobulin in the β-lactoglobulin–oligochitosan complexes was defined by the complex composition and supramolecular structure of oligochitosan.
... Chitosan and its derivatives induce systemic acquired resistance in plants against a range of pathogens, in addition to root-knot nematode M. incognita (Chakraborty et al., 2020). Also, several reports mentioned that glucanase, chitinase, peroxidase, phenylalanine ammonia-lyase, polyphenol oxidase, superoxide dismutase and catalase were triggered with the application of chitosan or its derivatives in certain crops (Burkhanova et al., 2007;Eilenberg et al., 2009;Yin et al., 2010;Chang & Kim, 2012;Orzali et al., 2014;Xing et al., 2015;Li et al., 2016). The levels of protein and some secondary metabolites linked to the protection from pathogens, such as phenolics and phytoalexins, were increased in treated plants (Lin et al., 2005;Hadwiger, 2013;Zhang et al., 2015). ...
Root-knot nematodes ( Meloidogyne spp.) have been reported to be responsible for large economic losses of agricultural crops due to their wide host range and variety of suitable climates. The control measures of these parasitic nematodes depend upon synthetic nematicides and a small number bio-based products. Chemical nematicides are eliciting adverse effects on the environment and human health. In the present study, an alternative tool, nano-chitosan was tested for the control the root-knot nematodes, Meloidogyne incognita , and Tobacco mosaic tobamovirus (TMV) in greenhouse-cultivated tomato. The effect of nano-chitosan on morphological (weight and length of shoot and root systems) and biochemical responses (Polyphenol oxidase, Peroxides, Total soluble phenol and Total protein) was assessed. The obtained results indicated that densities of Meloidogyne incognita alone or in the presence of TMV were decreased by nano-chitosan at a range of 45.89 to 66.61%, while root gall desntiy was reduced between 10.63 and 67.87%. Moreover, the density of TMV on tomato leaves singly or in the presence of M. incognita was suppressed at range of 10.26 to 65.00% after 20 days of infection, and reached up to 58.00% after 40 days of infection. However, soil application of nano-chitosan pre infection reduced TMV density only by 5.48%. Morphogenesis of tomato plants such as shoot and root systems were significantly improved. The impacts of nano-Chitosan applications on total soluble phenol, total protein, polyphenol oxidase and peroxides after 20 and 40 days of infections varied.
... Polysaccharide immunity inducer, such as amino oligosaccharides, chitosan, chitin, and lentinan, has been widely used in anti-plant virus diseases (Zhao et al., 2007). Lentinan, as a biological polysaccharide, has multiple disease-resistant functions, such as closing plant stomata, inducing the expression of plant resistance genes and improving plant disease-related enzyme activity (Yin et al., 2010). However, previously generated hydrogel loaded with LNT is confined in field application due to the limited induction time of lentinan and its instability in the complex field environment. ...
Control of plant virus disease largely depends on the induced plant defense achieved by the external application of synthetic chemical inducers with the ability to modify defense-signaling pathways. However, most of the molecular mechanisms underlying these chemical inducers remain unknown. Here, we developed a lentinan-loaded hy-drogel with a core-shell structure and discovered how it protects plants from different virus infections. The hydrogel was synthesized by adding a chitosan shell on the sur-face of the polyanion sodium alginate-calcium ion-lentinan (LNT) hydrogel (SL-gel) to form CSL-gel. CSL-gel exhibits the capacity to prolong the stable release of lenti-nan and promote calcium ions release. Application of CSL-gel on the root of plants induces broad-spectrum resistance against TMV, TuMV, PVX and TRV. Further-more, RNA-seq analysis identified that the calmodulin-like protein 19 gene (CML19) is upregulated by the sustained release of calcium ions from the CSL-gel, and silenc-ing and overexpression of CML19 alter the susceptibility and resistance of tobacco to TMV. Our findings provide evidence that the novel and synthetic CSL-gel with the sustainable release of LNT and calcium ion strongly inhibits the plant virus infection. This study uncovers a novel mode of action by which CSL-gel with the stable release of calcium ion triggers CML19 expression.
... Chitosan has been demonstrated to induce plant defenses in tomatoes (Benhamou et al., 1994;Benhamou and Th eriault, 1992), cucumber, chili seeds, strawberry fruits (El Ghaouth et al., 1992) and rose shrubs. Chitosan can activate innate immunity by stimulating hydrogen peroxide (H 2 O 2 ) production in rice Lin et al., 2005), induce a defense response by nitric oxide (NO) pathways in tobacco (Zhang et al., 2011;Zhao et al., 2007), promote the development and drought resistance of coffee (Dzung et al., 2011), support the synthesis of phytoalexin (Kim and Rajapakse, 2005), impact the jasmonic acid-ethylene (JA/ET) signaling marker in oilseed rape, cause changes in protein phosphorylation (Wang et al., 2006), activate mitogen-activated protein kinases (MAPKs) (Yin et al., 2010) and trigger defense-related gene expression (Chen et al., 2009). ...
With a very successful evolution history, insects place themselves as the largest inhabitants of the animal kingdom. Because of vast diversity, insects are capable to inhabit each and every possible corner of the atmosphere worldwide. We can find them everywhere except the saline water of the ocean. They are present in the driest place, i.e., deserts to swamps, forests and are even able to survive in severely harsh environments like in the pools of crude petroleum (Imms, 1964). The coexistence of all flora and fauna makes each coexisting entity become a beneficial as well as a harmful mate for each other in one or another way. So is true with insects, they also play both the roles of a friend as well as an enemy for human beings and crops by providing some of the beneficial products like honey, lac, silk, etc., on the contrary, some pose a high risk for humans as well as plants. Many of them are a carrier of a number of diseases and others become risky for agricultural crops and turn into a threat by becoming the reason for severe health and economic losses.
... Poly-and oligomers of variable, controlled sizes are used in the food, cosmetic, medical, agricultural and horticultural sectors. The physiological effects of chitosan oligomers in plants are the results of the capacity of this polycationic compound to bind a wide range of cellular components, including DNA, plasma membrane and cell wall constituents, but also to bind specific receptors involved in defense gene activation, in a similar way as plant defense elicitors (El Hadrami et al., 2010;Yin et al., 2010;Hadwiger, 2013;Katiyar et al., 2015). ...
... The CO comprises virtuous physio-chemical properties including water-solubility, encountering the obligatory requirements to use as a potential plant bio-vaccine. Thus, due to its distinguished properties, CO attracts researchers universally [100]. To regulate disease response and promote defence action, these derivatives are contested as core delivery carriers and elicitors [101,102]. ...
Sugarcane (Saccharum officinarum)-a prominent cash crop accounts for around 80% production of sugar worldwide. However, the productivity of sugarcane is declining (~40%) due to the attack of a perilous fungus-Fusarium moniliforme responsible for pokkah boeng (PB) disease. Presently, chemical methods are incisive where their harmful effects on living organisms cannot be overlooked. Introduction of disease-resistant cultivars and other biocontrol measures protect sugarcane to some extent. The multifunctional biopolymers like chitosan (CH) and its derivatives (irradiated chitosan [IRC]), chitooligosaccharides (CO) and nanochiotosan (NCH) offer endless opportunities to spring numerous aids for crops. CH is a dynamic plant elicitor with multifarious antimicrobial properties. The current review unleashes information on CH and its derivatives in controlling PB and fungal diseases of sugarcane along with other crops. We highlight the strategies that deploy CH as "biofungicide" to mitigate F. moniliforme. CH delays the postharvest decay in fruits (apple, strawberry, mango, banana, papaya) and vegetables (tomato, finger millet, capsicum, fenugreek) (~500-1000 ppm). NCH has been utilized as a foliar spray successfully (0.1%-1%) to protect staple crops (wheat, rice, maize) as well. Overall, NCH based strategies are noteworthy to protect sugarcane and other crops.
... CSP, is still rare. Pre-or post-harvest treatment with oligochitosan has been demonstrated can induce plant defense mechanisms against plant pathogens by stimulating defense-related enzymes, and enhancing activities of plant volatiles (Deng, Zhou, & Zeng, 2015;Yin, Zhao, & Du, 2010;Zhang & Chen, 2009). Inducing plant resistance with chitosan treatments has also been reported by Amini (2009), Benhamou, Lafontaine, & Nicole (1994), and Paz-Lago et al. (2000 against Fusarium wilt diseases, and Farouk, Ghoneem, & Ali (2008) for downy mildew. ...
... - 18,13 f ±0,83 P * * * * Chitosan có khối lượng phân tử thấp 16; 44,5 kDa có khả năng kháng khuẩn và nấm tốt hơn so với chitosan có khối lượng phân tử 80 kDa và chitosan thương mại (Mw = 109 kDa), điều đó chứng minh chitosan khối lượng phân tử thấp có khả năng kháng khuẩn và nấm rất tốt và tốt hơn chitosan có khối lượng phân tử cao (Yin et al., 2010). Khi kết hợp nano silica và chitosan thì có thể tăng cường khả năng kháng vi sinh vật của lớp màng bao chitosan (Dhanasingth et al., 2011). ...
Ổi là quả có đỉnh hô hấp nên diễn ra quá trình chín sau thu hoạch làm cho thịt quả bị mềm, màu sắc vỏ quả bị biến đổi, thời gian bảo quản ngắn. Đánh giá khả năng kháng các chủng vi sinh được phân lập từ quả ổi bị hư hỏng trong quá trình bảo quản bằng hỗn hợp chitosan khối lượng phân tử thấp và nano SiO2, đồng thời ứng dụng hỗn hợp để xử lí bao màng quả ổi nhằm tăng thời gian tồn trữ. Hỗn hợp chitosan khối lượng phân tử thấp và nano SiO2 có khả năng kháng tốt các các chủng vi sinh vật này. Ổi giống Đài Loan sau thu hoạch được xử lí bao màng bằng hỗn hợp 2% chitosan (MW 44,5 kDa) và 0,02% nano SiO2 có độ biến đổi màu sắc vỏ quả, độ cứng, hàm lượng vitamin C, tỉ lệ hư hỏng, tổng chất rắn hòa tan, tỉ lệ hao hụt khối lượng giảm chậm, bảo quản 12 ngày ở 15 ± 1oC, 80 ± 5% RH gấp đôi thời gian so với không xử lí.
... Poly-and oligomers of variable, controlled sizes are used in the food, cosmetic, medical, agricultural and horticultural sectors. The physiological effects of chitosan oligomers in plants are the results of the capacity of this polycationic compound to bind a wide range of cellular components, including DNA, plasma membrane and cell wall constituents, but also to bind specific receptors involved in defense gene activation, in a similar way as plant defense elicitors (El Hadrami et al., 2010;Yin et al., 2010;Hadwiger, 2013;Katiyar et al., 2015). ...
... The potential for plant immunization for pathogen control through plant treatments with "vaccines" of diverse structures is already a topic in the literature. For instance, oligochitosans are described as vaccines because of their stimulation of plant immunity (Yin et al., 2010). The paper "Using green vaccination to brighten the agronomic future" focusses on volatiles, chemicals and beneficial microbes as vaccines of promise (Luna, 2016). ...
A plethora of compounds stimulate protective mechanisms in plants against microbial pathogens and abiotic stresses. Some defense activators are synthetic compounds and trigger responses only in certain protective pathways, such as activation of defenses under regulation by the plant regulator, salicylic acid (SA). This review discusses the potential of naturally occurring plant metabolites as primers for defense responses in the plant. The production of the metabolites, hexanoic acid and melatonin, in plants means they are consumed when plants are eaten as foods. Both metabolites prime stronger and more rapid activation of plant defense upon subsequent stress. Because these metabolites trigger protective measures in the plant they can be considered as “vaccines” to promote plant vigor. Hexanoic acid and melatonin instigate systemic changes in plant metabolism associated with both of the major defense pathways, those regulated by SA- and jasmonic acid (JA). These two pathways are well studied because of their induction by different microbial triggers: necrosis-causing microbial pathogens induce the SA pathway whereas colonization by beneficial microbes stimulates the JA pathway. The plant’s responses to the two metabolites, however, are not identical with a major difference being a characterized growth response with melatonin but not hexanoic acid. As primers for plant defense, hexanoic acid and melatonin have the potential to be successfully integrated into vaccination-like strategies to protect plants against diseases and abiotic stresses that do not involve man-made chemicals.
... Ascophylum nodosum [92,93] a Seaweed extract [94,95] Cold tolerance Alanine, arginine [96] Ascophylum nodosum [96][97][98] Salt tolerance Proline [99] a Seaweed extract [100] Heat tolerance Glutamic acid and γaminobutyric acid [101] a Seaweed extract [102] Chelating It is widely accepted that the defense mechanism occurring at the molecular level in the cell wall is activated by oligosaccharides that resemble the ones found in the pathogens' cell wall. At least five stages of plant's defense mechanism are known: (i) recognition in the plant's cell membrane, (ii) signal transfer, amplification, and activation of response genes, (iii) increase in response proteins, (iv) induction of secondary metabolites biosynthesis related to defense, and (v) defense reaction [112,113]. ...
Oceans are rich sources of biologically active compounds found in many organisms. In recent years, investigations to explore biostimulant compounds of marine origin have become increasingly important for their use in agriculture. Biostimulants are defined as molecules of biological origin capable of positively influencing the growth and development of plants, increasing tolerance to abiotic and biotic stress factors, and promoting crop quality and yield. Seaweeds and microalgae are sources of polysaccharides and phytohormones, which are considered molecules with biostimulating potential in plants. Thus, biostimulants act in different conditions of environmental stress for the plant and have been claimed as an ecological alternative in substitution to the synthetic agrochemicals used in agriculture. In this chapter, the perspectives for the development of new technologies for biostimulant products are presented, focusing on the biotechnological potential of algal polysaccharides in the design of nanotechnological products based on the delivery of bioactive compounds to plants.
Root-knot nematodes (Meloidogyne spp.) are dangerous parasites of many crops worldwide. The threat of chemical nematicides has led to increasing interest in studying the inhibi-tory effects of organic amendments and bacteria on plant-parasitic nematodes, but their combination has been less studied. One laboratory and four glasshouse experiments were conducted to study the effect on M. javanica of animal manure, common vermicompost, shrimp shells, chitosan, compost and vermicompost from castor bean, chinaberry and aru-gula, and the combination of arugula vermicompost with some bacteria, isolated from vermi-compost or earthworms. The extract of arugula compost and vermicompost, common vermicompost and composts from castor bean and chinaberry reduced nematode egg hatch by 12-32% and caused 13-40% mortality of second-stage juveniles in vitro. Soil amendments with the combination vermicompost of arugula + Pseudomonas. resinovorans + Sphingobacterium daejeonense + chitosan significantly increased the yield of infected tomato plants and reduced nematode reproduction factor by 63.1-76.6%. Comparison of chemical properties showed that arugula vermicompost had lower pH, EC, and C/N ratio than arugula compost. Metagenomics analysis showed that Bacillus, Geodermatophilus, Thermomonas, Lewinella, Pseudolabrys and Erythrobacter were the major bacterial genera in the vermicompost of arugula. Metagenomics analysis confirmed the presence of chitinoly-tic, detoxifying and PGPR bacteria in the vermicompost of arugula. The combination of aru-gula vermicompost + chitosan + P. resinovorans + S. daejeonense could be an environmentally friendly approach to control M. javanica.
Control of plant virus diseases largely depends on the induced plant defence achieved by the external application of synthetic chemical inducers with the ability to modify defence‐signalling pathways. However, most of the molecular mechanisms underlying these chemical inducers remain unknown. Here, we developed a chitosan‐coated lentinan‐loaded hydrogel and discovered how it protects plants from different virus infections. The hydrogel was synthesized by coating chitosan on the surface of the calcium alginate‐lentinan (LNT) hydrogel (SL‐gel) to form a CSL‐gel. CSL‐gels exhibit the capacity to prolong the stable release of lentinan and promote Ca ²⁺ release. Application of CSL‐gels on the root of plants induces broad‐spectrum resistance against plant viruses (TMV, TRV, PVX and TuMV). RNA‐seq analysis identified that Nicotiana benthamiana calmodulin‐like protein gene 3 ( NbCML3 ) is upregulated by the sustained release of Ca ²⁺ from the CSL‐gel, and silencing and overexpression of NbCML alter the susceptibility and resistance of tobacco to TMV. Our findings provide evidence that this novel and synthetic CSL‐gel strongly inhibits the infection of plant viruses by the sustainable release of LNT and Ca ²⁺ . This study uncovers a novel mode of action by which CSL‐gels trigger NbCML3 expression through the stable and sustained release of Ca ²⁺ .
Chickpea is the widely consumed dietary legume contributing 18% of global pulse production. Ongoing climatic changes impose several abiotic and biotic stresses on the yield and productivity of chickpeas. Fusarium oxysporum f. sp. ciceris (Foc) is a major soil‐born pathogen which causes up to 100% yield loss. Among the biocontrol strategies to manage the disease problem, the use of chitosan nanoparticles (CNPs) is now emerging as an attractive and beneficial option. CNPs have a major role in mitigating different stress conditions in plants by eliciting a variety of defence responses including pathogen‐related proteins, antioxidants, phytoalexins, proteinase inhibitors, lignin deposition, callose deposition, and so on. This is suggested as an environmentally friendly alternative to chemicals to prevent seed infestation from various pests. It is used as a seed coating agent which acts as a feeding deterrent and barrier to crop pests. Further, chitosan application can mitigate multiple abiotic and biotic stresses. Considering these properties of chitosan will certainly reduce the negative impact of Fusarium on the yield and quality of chickpeas. This review presents an overview of chickpea cultivation, yield losses due to diseases, chitosan application, its derivatives, and mode of action for the management of chickpea wilt in a sustainable manner.
In sustainable agriculture, integrated pest and nutrient management play a vital role in using environmentally free and natural compounds for pest, disease management, soil fertility, and food safety. The biopolymer chitosan and its derivatives are synthesized from the natural compound chitin which shows promising activity in agriculture. Chitosan and its nano-composite have excellent biological activities in plant growth, development and defense. The chitosan nano-composite enhances the effectivity, bio-efficacy and bio-availability of chitosan using a controlled delivery system for pest and nutrient management. The nanoparticles of chitosan effectively work as a plant growth regulator, and growth stimulants by enhancing secondary metabolites production in plants. Chitosan and its derivatives are involved in stimulating the physiological parameter as well as plant hormones for growth and development. Moreover, chitosan-based nano-composites act as excellent fertilizers and soil conditioners by maintaining the Carbon: Nitrogen ratio. The high intake and absorption of chitosan-based nano-fertilizers and micronutrients enhance the rate of plant metabolic pathways, which results in the improvement of crop nutrient management. Chitosan and its nanoparticles persuade the plant defense mechanism by increasing immune response in plants and play a vital role in plant protection. Chitosan and its nanoparticles have excellent activity against plant pathogens including microbes, viruses, fungi, nematodes and insects. The present book chapter emphasizes on biological activities and mode of action of chitosan and its nanoparticles in agriculture for plant growth, development, protection, productivity and yield of a crop.
A nanotechnology is an interdisciplinary approach offering novel management options against different biotic stresses threatening agricultural production. The realized adverse impact of chemical pesticides on a global scale also compels the use of novel pest management strategies. At this juncture, a combination of nanotechnology with some natural and biologically important constituents offers high target efficacy along with unique modes of action with low environmental toxicity. Among the biologically active products, the biopolymer, chitosan has attracted more attention because of its unique characteristics and biological activities. Nanotechnology-derived products of chitosan either single or in combination with other pesticidal compounds showed a great promise against both phytopathogenic fungi and phytophagous insect pests. The two-way action (direct management and elicitation of immune response in the host) of these nano-chitosan compounds also offers a novel mechanism to tackle the pest problems in agriculture. Although results obtained were highly encouraging, there is a pressing need to strategically organize the type of chitosan, associated pesticide compounds, molecular weight, solubility, positive charge density, molecular modification, pH, concentration, and chelation capacity, etc. to realize the full potential of this technology. So, to broaden the chitosan's pesticide applicability against plant diseases and pests, comprehensive knowledge of its activity is necessary. This chapter describes some recent findings on the use of nano chitosan-based products in pest and disease management. In addition, we consider the new technological applications of chitosan products in agriculture and perspectives on future studies in this field. Modes of action of these products against several target pathogenic microorganisms and pests are also discussed.
To feed the increasing world population there is a great need to improve crop productivity, which resulted in excessive chemical use and environmental and health concern. In this regard integration of advanced technology is required by minimizing the input of pesticide and fertilizer per unit while improving crop productivity. With some inimitable properties like antimicrobial and plant growth-promoting activities, chitosan is increasingly gaining major research interest in the agricultural field. Chitosan nanoparticles represent themselves as an efficient encapsulating agent due to their natural affinity toward metals. Metal encapsulating chitosan nanoparticles are highly applicable in addressing key agricultural issues like micronutrient deficiency and excessive chemical use. Efficient nutrient utilization and a healthy plant system are the sole criteria for improved defense status and crop productivity. Herein we have summarized the various chitosan-based nanomaterials that have been successfully utilized for the nutrient supply in plants.
Chitin, the second most abundant polymer on earth, can be degraded from the enzyme chitinases, being also potential agent for the biological control of plant and human diseases. In its nanosize, the polymer together with the derived compounds has an enormous agricultural and pharmaceutical potential activity. Chitin and chitosan nanofibers, for example, may be used for the biological control of plant diseases as biopesticides against various pathogens as well as for their role in human health are effective as bio marker of innate immunity, wound healing compound, and natural carriers for delivery of drugs and food. The binomial activity in plants and humans of these natural polymers will be reported and discussed underlining the necessity to save the environment, reducing the consumption of chemicals and toxic pesticides and drugs.
Cultivation of horticulture crops plays an important role in the fulfillment of our daily requirement of the recommended nutritional demand. Hence, it is essential to develop crops using eco-friendly, safe and chemical-free farming techniques. The mounting demand for food has led to extensive advances in the field of sustainable crop management and integrated pest management. For sustainable agriculture, the application of biological techniques to avert the use of chemical products has led to the investigation of bio polymers-based materials. Chitosan, a naturally occurring biopolymer, acts as an ideal capping and stabilizing agent for the formation of nanocomposites of metals and organic compounds. Chitosan and chitosan-based nanoparticles have shown promising results in horticultural crops as fertilizers, soil conditioning agents, plant disease control and insecticidal agents, ripening retardants, and seed and fruit coatings. Moreover, there are reports state that chitosan regulates many genes in plants, stimulating certain pathways responsible for plant defense. Presently, chitosan-based nanoparticles have applications in plant nourishment with great efficacy, which works in synergy with the soils' ecosystem. Chitosan-based agro-nanochemicals have also been revealed to induce defense systems in preharvest and postharvest vegetables and fruits against viruses and pathogenic bacteria, insects, nematodes, fungi and abiotic stresses. Additionally, chitosan nanoparticles have coating ability, which enhances the biophysical properties of postharvest crops and improves their longevity. Based on such encouraging properties, chitosan-based nanoparticles provide multiple advantages and open up unattained prospective future avenues in horticultural systems. This review focuses on the past, present and future perspectives, along with the roles and functions of chitosan and chitosan-based nanoparticles in horticultural crops for enhancing the quality, productivity and yield, which is beneficial for eventual improvement programs.
Parkinson's disease (PD), the second most common neurodegenerative disease, is a threat to patients due to the inability to prevent or decelerate disease progression. Currently, most clinical drugs for the treatment of PD are synthetic drugs that always present undesirable adverse or toxic effects. Chitosan oligosaccharide (COS) is a natural oligosaccharide that has been considered relatively safe and studied in the therapeutic effects on different types of neuronal disorders. In this study, we separated four COS monomers (COSs) including chitobiose (COS2), chitotriose (COS3), chitotetraose (COS4) and chitopentaose (COS5) to explore their structure-activity relationship in PD mice induced by 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP). Techniques including TLC, HPLC, MS, and NMR were applied to investigate the purity and structure of the COSs. After the oral administration of COSs, behavior indexes, pathological indexes, cytokines, and expression of proteins in the nigrostriatal pathway of the mice were analyzed. The results showed that the four COSs were fully deacetylated and the purity was >90%. Additionally, the neurobehavioral deficits of the PD mice were improved by treatment with COSs. The results further proved that COSs could protect the TH-labelled dopaminergic neurons via reducing the overexpression of α-synuclein, alleviating neuroinflammation, and activating the PI3K/Akt/Bcl-2 pathway to reduce apoptosis. COS3 exhibited a better effect on protecting dopaminergic neurons; however, COS2 provided a better effect on reducing the overexpression of α-synuclein. To conclude, the neuroprotective activity makes COSs a viable candidate as an ingredient for healthcare products.
The agriculture sector is facing many challenges, like inefficiency, pollution, development of resistances by pathogens, accumulation of heavy metals in soil. Nanotechnology can address many of these aspects. Moreover, market requests are leading toward new strategies of plant protection and pest management, that rely on natural compounds. In the following chapter, the development of organic nanoparticles as green, efficient and innovative agrochemicals is presented as a solution, by deepening among others their possible application as tools to reduce the use of copper.
Long-chain chitooligosaccharides (COS) with degree of polymerization (DP) more than 4 are known to have potential biological activities. A hyper-transglycosylating mutant of an endo-chitinase from Serratia proteamaculans (SpChiD-Y28A) was used to synthesize COS with DP6 and DP7 using COS DP5 as substrate. Purified COS with DP5-7 were tested to elicit the defense response in rice seedlings. Among the COS used, DP7 strongly induced oxidative burst response as well as peroxidase, and phenylalanine ammonia lyase activites. A few selected marker genes in salicylic acid (SA)- and jasmonic acid-dependent pathways were evaluated by real-time PCR. The expression levels of pathogenesis-related (PR) genes PR1a and PR10 and defense response genes (chitinase1, peroxidase and β -1,3-glucanase) were up regulated upon COS treatment in rice seedlings. The DP7 induced Phenylalanine ammonia lyase and Isochorismate synthase 1 genes, with concomitant increase of Mitogen-activated protein kinase 6 and WRKY45 transcription factor genes indicated the possible role of phosphorylation in the transmission of a signal to induce SA-mediated defense response in rice.
Деякі представники мікофлори насіння пшениці озимої з’являються у ній з моменту цвітіння до збору врожаю. Тому обприскування рослин на початку цвітіння та пізніше повинно істотно впливати на мікокомплекс зерна. Впродовж 2018–2020 рр. провели вивчення впливу обприскування на формування мікофлори насіння пшениці озимої в умовах північно-схід-ного Лісостепу України. До дослідження залучили такі препарати: Фалькон, к.е, Імуноцитофіт, тб, Трихофіт, р., Гауп-син, р. і Хітозан, тб. Аналіз мікокомплексу провели на картопляно-глюкозному агарі. Хімічний та біологічні препарати істотно регулювали формування мікофлори. Цей захід не лише змінив кількість виділених видів/родів, але і загальний склад грибів. У 2018 р. вони зменшили кількість домінуючих альтернарієвих грибів і викликали появу мукорових, особливо у варіанті з одночасним застосуванням Фалькону, к.е та Імуноцитофіту, тб. У 2019 р. застосування фунгіцидів призвело до зменшення кількості домінуючих А. pullulans й Alternaria sp. та до збільшення виділення небезпечного N. oryzae, що істотно вплинуло на довжину проростків. Найвищу кількість цього виду відмітили у варіантах із застосуванням Фалькону, к.е. У 2020 р. відмітили найбільшу зміну складу мікофлори за три роки вивчення ефективності фунгіцидів. Всі препарати знизили кількість домінуючих альтернарієвих грибів та викликали значну появу A. pullulans, який був відсутній на контролі. Трирічний аналіз випробування Фалькону, к.е. та Трихофіту, р. проти домінуючих альтернарієвих грибів показав істотні зміни їх чисельності. Середній показник ефективності за три роки у першого препарату склав 65,1 %, у другого – 26,2 %. Обприскування фунгіцидами також істотно вплинуло на масу 1000 насінин. Здебільшого їх застосування збільшило цей показник, за винятком 2018 р., коли у мікофлорі насіння вони спровокували появу мукорових грибів. Найбільш виповне-ним насіння сформувалось у варіантах з обприскуванням біологічними препаратами. Вивчення впливу обприскування рос-лин на довжину рослин за проростання насіння показало найкращі результати у варіантах також з біофунгіцидами. Отже, обприскування пшениці озимої хімічним та біологічними препаратами викликає зменшення домінуючих видів у мікофлорі насіння, що призводить до появи чи збільшення інших її складових. Дуже часто одні представники замінюють інші гриби.
Induction of resistance to downy mildew caused by Plasmopara halstedii in sunflower was studied after treatment with chitosan. Treatment of sunflower seeds with 5% chitosan resulted in decreased disease severity and offered 46 and 52% protection under greenhouse and field conditions respectively. The induction of resistance to P. halstedii by chitosan was accompanied by the accumulation of various host defense-related enzymes in susceptible sunflower seedlings. Enhanced activation of catalase (CAT) and phenylalanine ammonia lyase (PAL) was observed at 6 h and 9 h post-inoculation respectively, while peroxidase (POX), polyphenol oxidase (PPO) and chitinase (CHI) levels were high at 12 h post-inoculation in sunflower seedlings raised from seeds treated with chitosan. Northern hybridization analysis revealed increased levels of transcripts for five known defense response genes viz., Pr-1a, b-1,3-glucanase, chi-tinase, peroxidase and chalcone synthase in these seedlings. This enhanced and early activation of defense-related responses in the susceptible cultivar Morden treated with chitosan was comparable to that in the resistant cultivar. The results indicate that chitosan induced resistance against P. halstedii in sunflower is mediated through the enhanced expression of genes for defense-related proteins.
Common rue (Ruta graveolens L.) accumulates various types of secondary metabolites, such as coumarins furanocoumarins, acridone and quinolone alkaloids and flavonoids. Elicitation is a tool extensively used for enhancing secondary-metabolite yields. Chitin and chitosan are examples of elicitors inducing phytoalexin accumulation in plant tissue. The present paper describes the application of chitin and chitosan as potential elicitors of secondary-metabolite accumulation in R. graveolens shoots cultivated in vitro. The simple coumarins, linear furanocoumarins, dihydrofuranocoumarins and fluoroquinolone alkaloids biosynthesized in the presence of chitin and chitosan were isolated, separated and identified. There was a significant increase in the growth rate of R. graveolens shoots in the presence of either chitin or chitosan. Moreover, the results of the elicitation of coumarins and alkaloids accumulated by R. graveolens shoots in the presence of chitin and chitosan show that both compounds induced a significant increase in the concentrations of nearly all the metabolites. Adding 0.01% chitin caused the increase in the quantity (microg/g dry weight) of coumarins (pinnarin up to 116.7, rutacultin up to 287.0, bergapten up to 904.3, isopimpinelin up to 490.0, psoralen up to 522.2, xanhotoxin up to 1531.5 and rutamarin up to 133.7). The higher concentration of chitosan (0.1%) induced production of simple coumarins (pinnarin up to 116.7 and rutacultin up to 287.0), furanocoumarins (bergapten up to 904.3, isopimpinelin up to 490.0, psoralen up to 522.2, xanhotoxin up to 1531.5) and dihydrofuranocoumarins (chalepin up to 18 and rutamarin up to 133.7). Such a dramatic increase in the production of nearly all metabolites suggests that these compounds may be participating in the natural resistance mechanisms of R. graveolens. The application of chitin- and chitosan-containing media may be considered a promising prospect in the biotechnological production of xanthotoxin, isopimpinelin, psoralen, chalepin or methoxylated dictamnine derivatives.
Two putative elicitors of disease resistance (acibenzolar-S-methyl and chitosan) were tested for their effect on crown rot (Phytophthora cactorum) in strawberry. The effect of both compounds was enhanced when the time between treatment and inoculation was prolonged from 2 to 20 days. There were no significant differences between treatments when the concentration of acibenzolar-S-methyl was increased from 10 to 1,000 mug a.i./plant. The lowest tested concentrations of chitosan (10 and 50 mug a.i./plant) resulted in a lower disease score compared with the highest concentrations (250 or 1,000 mug a.i./plant). There were no differences in disease score between treatment with fosetyl-Al, acibenzolar-S-methyl, or chitosan when applied 5 or 15 days before inoculation. The effect of acibenzolar-S-methyl and chitosan also was tested against P. fragariae var. fragariae in alpine strawberry (Fragaria vesca var. alpina cv. Alexandria). Chitosan had no effect, whereas fosetyl-Al and all treatments with acibenzolar-S-methyl (50 or 250 mug a.i./plant; 5, 10, 20, or 40 days before inoculation) reduced the severity of the disease. There were no significant differences between acibenzolar-S-methyl and fosetyl-Al when applied at the same time. Acibenzolar-S-methyl and chitosan at concentrations of 0.5, 5, 50, and 500 mug a.i. ml(-1) in V8 juice agar were tested for possible effects on P. cactorum and P. fragariae var. fragariae in vitro. Only chitosan at concentrations of 50 and 500 mug ad. ml-1 had a growth-retarding effect on P. cactorum. Both acibenzolar-S-methyl and chitosan at a concentration of 500 Ng a.i. ml(-1) reduced the growth rate of P. fragariae var. fragariae.
Oligochitosan is a potent plant defense elicitor. In this paper, a novel Brassica napus mitogen-activated protein kinase (MAPK) gene induced by oligochitosan was isolated by rapid amplification of cDNA ends technique
and designated as BnOIPK (oligochitosan-induced protein kinase (OIPK)). BnOIPK, with high sequence similarity to previously reported plant MAPK genes, encodes a 373-amino acid protein and belongs to the
B subgroup of plant MAPK. Bioinformatics analysis showed BnOIPK contains one phosphorylation motif (TEY) and a conserved common docking domain in its C-terminal extension. With a constitutive
expression in seedling leaves, BnOIPK is further upregulated upon treatment with plant hormone jasmonic acid (JA), but did not markedly respond to salicylic acid
and abscisic acid. Activation of BnOIPK transcripts induced by oligochitosan depending on nitric oxide (NO) and hydrogen peroxide (H2O2) was identified by using NO, H2O2, and their scavenger, respectively. Polyclonal antibody BOK was prepared by using a 69-kD GST-BnOIPK fusion protein which
was produced from pGEX-4T-1 vector. Western-blot assays showed BnOIPK could be induced by oligochitosan and JA at a short
time. All these results suggest that BnOIPK might be a key node of JA-mediated defense signaling and act on the downstream of NO and H2O2.
KeywordsOligochitosan-
Brassica napus
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BnOIPK
-Plant defense-Signal transduction
We studied the effects of chitooligosaccharides (ChOS) with a mol wt of 5 kD, the degree of acetylation of 65%, and the concentrations from 0.01 to 100 mg/l on the content of hydrogen peroxide in incubation medium and the activity of anionic peroxidase (pI 3.5) in the segments of wheat (Triticum aestivum) coleoptiles. H2O2 production and peroxidase activity were found to be dependent on the ChOS concentration. After 3 h of incubation, the highest H2O2 level in medium was observed at 0.01 mg/l ChOS, whereas after 6h, at 1 mg/l. After 3 h of incubation, ChOS suppressed peroxidase activity. After 6 h of incubation, high ChOS concentrations enhanced peroxidase activity. IAA favored H2O2 accumulation in medium and suppressed anionic peroxidase. The involvement of ChOS in the control of the level of reactive oxygen species and anionic peroxidase activity in plant cells is suggested.
The development and the possible mechanism of the chitosan-induced resistance to viral infection were investigated in potato plants. The plants were sprayed with a solution of chitosans (1 mg/ml) with the mol wt of 3, 36, and 120 kD. After 1, 2, 3, or 4 days, the treated leaves were cut off and mechanically infected with the potato virus X (PVX). The disks cut out from the inoculated leaves were used for determining virus accumulation, callose content, and ribonuclease and -1,3-glucanase activities. In another set of experiments, the plants were infected with PVX within 1, 4, or 8 days after chitosan treatment, and the number of systemically infected plants was determined. It was found that, a day after treatment, the plants acquired a resistance to viral infection. The disks from the chitosan-treated leaves, as compared to the control, accumulated less amount of virus. The chitosan treatment also significantly decreased the number of systemically infected plants as compared to the control. After 2–3 days, the resistance disappeared or even gave way to an increased susceptibility to the infection; subsequently, the resistance increased again. The extent of the resistance correlated with the callose content and the level of ribonuclease activity observed on the infection day. The resistance towards the infection with PVX is probably mediated by the callose and ribonuclease induction. The cultivation of test-tube potato plants from the cuttings previously infected with PVX on the chitosan-containing nutrient medium did not eradicate the viral infection from the plants.
Enzymatic degradation of chitosan polymer with Pectinex Ultra SPL was used to obtain derivatives with biological potential
as protective agents against Phytophthora parasitica nicotianae (Ppn) in tobacco plants. The 24h hydrolysate showed the highest Ppn antipathogenic activity and the chitosan native polymer the lowest. The invitro growth inhibition of several Phytophthora parasitica strains by two chitosans of different DA was compared. While less acetylated chitosan (DA 1%) fully inhibited three P. parasitica strains at the doses 500 and 1000mg/l the second polymer (DA 36.5%) never completely inhibited such strains. When comparing
two polymers of similar molecular weight and different DA, again the highest antipathogenic activity was for the less acetylated
polymer. However, degraded chitosan always showed the highest pathogen growth inhibition. Additionally, a bioassay in tobacco
seedlings to test plant protection against Ppn by foliar application demonstrated that partially acetylated chitosan and its hydrolysate induced systemic resistance and
higher levels of glucanase activity than less acetylated chitosan. Similarly, when treatments were applied as seeds coating
before planting, about 46% of plant protection was obtained using chitosan hydrolysate. It was concluded that, while less
acetylated and degraded chitosan are better for direct inhibition of pathogen growth, partially acetylated and degraded chitosan
are suitable to protect tobacco against P. parasitica by systemic induction of plant resistance.
The 12-oxo-phytodienoic acid reductase (OPR) is a key enzyme in jasmonic acid (JA) biosynthesis. Previously, we reported the
presence of 13 OPR isogenes (OsOPR1-13) in rice. OsOPRs phylogenetically belong to two subgroups, OPRI and OPRII. OsOPR13 is assigned to the second subgroup, which
is involved in JA biosynthesis, while the others are found in the first subgroup. Here, we systematically investigated transcript
levels of OsOPRs in various tissues and against diverse environmental stresses. Each gene was differentially involved in flower maturation,
showing a tissue-specific response. OsOPR1, OsOPR2, and OsOPR13 were also active in responses to wounding, a fungal elicitor (chitosan), salt, UV-C irradiation, H2O2, and ozone exposure. In the case of JA-responsive OsOPRs (OsOPR1, OsOPR2, OsOPR6, OsOPR10, and OsOPR13), co-application of JA and SA suppressed jasmonate-induced transcript levels and delayed OsOPR10 expression. We also investigated the biochemical properties of OsOPR1 and found a flavin cofactor with optimal activity at
pH 7.8 and values of 0.048min−1 kcat and 8.33μM Km for (9S,13R)-12-oxo-phytodienoic acid. Here, we discuss the role of OsOPRs in stress responses and floral development.
We studied the effects of low-molecular-weight water-soluble derivatives of chitin, chitooligsaccharides (ChOS) with a mol
wt of 5–10 kD and the degree of acetylation of 65% on expression and molecular heterogeneity of peroxidase and the content
of phytohormones in wheat plants differing in their resistance to the causal agents of root rots. Plant infection or their
treatment with ChOS induced expression of the gene for anionic peroxidase and enhanced enzyme activity, and these processes
depended on the degree of wheat resistance. They were more intense in the resistant cultivar. Treatment of susceptible plants
with ChOS prevented a pathogen-induced drop in the cytokinin level, thus simulating defensive responses, which are characteristic
of the resistant plants.
Chitosan (β-1,4-linked glucosamine oligomer) derived from crab shells conferred a high protection of grapevine leaves against
grey mould caused by Botrytis cinerea. Under controlled conditions, it was shown to be an efficient elicitor of some defense reactions in grapevine leaves and
to inhibit directly the in vitro development of B. cinerea. Treatment of grapevine leaves by chitosan led to marked induction of lipoxygenase (LOX), phenylalanine ammonia-lyase (PAL)
and chitinase activities, three markers of plant defense responses. Dose-response curves show that maximum defense reactions
(PAL and chitinase activities) and strong reduction of B. cinerea infection were achieved with 75–150mgl−1 chitosan. However, greater concentrations of chitosan did not protect grapevine leaves with the same efficiency, but inhibited
mycelial growth in vitro. Present results underlined the potency of chitosan in inducing some defense responses in grapevine leaves which in turn
might improve resistance to grey mould.
Chitosan (CHT), a deacetylated chitin derivative, and benzo-(1,2,3)- thiadiazole-7-carbothioic acid S-methyl ester (BTH), a non toxic synthetic functional analogue of salicylic acid, were applied as foliar spray to barley plants (Hordeum vulgare L.), to compare their effectiveness in inducing resistance against Blumeria graminis f. sp. hordei and to investigate the underlying defence response. After an induction phase of 3 days (IP, time elapsed between treatment and fungal inoculation) both compounds reduced significantly the infection on the primary leaf, namely of 55.5% for CHT and of 68.9% for BTH, showing the induction of a good level of local resistance (LAR). A 5-day IP further reduced the infected areas in BTH treated plants (-77.2%) but not in CHT treated ones (-47.1%). Furthermore, both CHT and BTH also induced SAR, being the infection in the second non treated leaves reduced of 57% and 76.2%, respectively, as evaluated at 10-day IP. Both BTH and CHT induced oxidative burst and phenolic compound deposition in treated leaves, creating an hostile environment that slowed down the fungal spreading by impairing haustorium development. However, the greater efficacy of BTH was possibly due to: i) a greater reinforcement of papilla; ii) a higher level and the more homogeneous diffusion of H2O2 in the treated leaf tissues and iii) an induced hypersensitive-like response in many penetrated cells. © 2007 International Organization for Biological Control (IOBC).
The objective of this study was to evaluate the effects of chitosan and chitin oligomers on gray mould caused by Botrytis cinerea in cucumber plants. Almost complete inhibition of Botrytis conidia germination was found, in vitro, at 50 ppm chitosan but not with chitin oligomers at any concentrations. It was found that chitosan controlled the gray mould caused by B. cinerea (0.45 disease index) compared with control (3.5 disease index). Chitin oligomers did not show any effect (3.5 disease index). Although chitin oligomers elicited chitosanase activity by 2.4 folds and peroxidase activity by 2.0 folds and chitosan elicited their activities only by 1.9 and 0 fold, respectively; disease control was not affected. Spraying chitosan 1 h before inoculation with Botrytis conidia decreased gray mould incidence by 65%. Spraying chitosan 4 or 24 h before inoculation reduced disease development by 82% and 87%, respectively. However, spraying chitosan on the leaves 1 h after inoculation decreased gray mould only by 52%. It is concluded that although a dual mode of action was involved in the control of gray mould by chitosan, the antifungal activity of the compound was an essential factor. The induction of the defence response without the antifungal activity was not enough to suppress the disease.
Chitosan, a given name to a deacetylated form of chitin, is a natural biodegradable compound derived from crustaceous shells such as crabs and shrimps, whose main attributes corresponds to its polycationic nature. Chitosan has been proven to control numerous pre and postharvest diseases on various horticultural commodities. It has been reported that both soil and foliar plant pathogens fungal, bacterial and viral may be controlled by chitosan application. Microscopical observations indicate that chitosan has a direct effect on the morphology of the chitosan-treated microorganism reflecting its fungistatic or fungicidal potential. In addition to its direct microbial activity, other studies strongly suggest that chitosan induces a series of defence reactions correlated with enzymatic activities. Chitosan has been shown to increase the production of glucanohydrolases, phenolic compounds and synthesis of specific phytoalexins with antifungal activity, and also reduces macerating enzymes such as polygalacturonases, pectin metil esterase etc. In addition, chitosan induces structural barriers for example inducing the synthesis of lignin-like material. For some horticultural and ornamental commodities, chitosan increased harvested yield. Due to its ability to form a semipermeable coating, chitosan extends the shelf life of treated fruit and vegetables by minimizing the rate of respiration and reducing water loss. As a nontoxic biodegradable material, as well as an elicitor, chitosan has the potential to become a new class of plant protectant, assisting towards the goal of sustainable agriculture.
Many researchers have focused chitosan as a source of potential bioactive material during past few decades. However, chitosan has several drawbacks to be utilized in biological applications, including poor solubility under physiological conditions. Therefore, a new interest has recently been emerged on partially hydrolyzed chitosan, chitosan oligosaccharides (COS). During the resent past, several technological approaches have been taken to prepare COS and, enzymatic preparation methods captured a great interest due to safe and non-toxic concerns. With time, new improvements were introduced to enzymatic production and presently it has been developed to a continuous production process. Many of the biological activities reported for COS, such as antimicrobial, anticancer, antioxidant, and immunostimulant effects are depend on their physico-chemical properties. In this review, we have summarized different enzymatic preparation methods of COS and some of their reported biological activities.
NO (nitric oxide) and H2O2 (hydrogen peroxide) are important signaling molecule in plants. Brassica napus L. was used to understand oligochitosan inducing production of NO (nitric oxide) and H2O2 (hydrogen peroxide) and their physiological function. The result showed that the production of NO and H2O2 in epidermal cells of B. napus L. was induced with oligochitosan by fluorescence microscope. And it was proved that there was an interaction between NO and H2O2 with L-NAME (NG-nitro-l-arg-methyl eater), which is an inhibitor of NOS (NO synthase) in mammalian cells that also inhibits plant NO synthesis, and CAT (catalase), which is an important H2O2 scavenger, respectively. It was found that NO and H2O2 induced by oligochitosan took part in inducing reduction in stomatal aperture and LEA protein gene expression of leaves of B. napus L. All these results showed that oligochitosan have potential activities of improving resistance to water stress.
Chitosan is one of the most abundant marine-based biopolymers. Low molecular weight and oligomeric chitosans are water-soluble hydrolysates of chitosan. They have been shown to have a wide range of biological activities and industrial applications. In particular, low molecular weight and oligomeric chitosans have been reported to have the health benefits such as immunity regulation, anti-tumor, liver protection, blood lipids lowering, anti-diabetic, antioxidant and anti-obesity. In this paper, the preparation and analytical methods, and bioactivities of these low molecular weight and oligomeric chitosans were reviewed, with the latest progresses introduced and discussed.
A high-affinity binding site for N-acetylchitooligosac-chlaride elicitor was found to localize in the plasma membrane from suspension-cultured rice cells. Binding
kinetics as well as the specificity of this binding site corresponded well with the behavior of the rice cells to the editor.
These characteristics suggest that the binding site represents a functional receptor for N-acetylchitooligosaccharide elicitor in rice.
The growth of etiolated wheat (Triticum aestivum L,. cv. Lumai No.22) seedlings and the activation of the cell cycle in embryo cells were estimated by now cytometric analyses in wheat after the seeds being treated with oligoglucosamine and deoxynivalenol (DON). The results indicated that both the root number in etiolated wheat seedlings and the activation of the cells which had been arrested at G(1) phase of the cell cycle in wheat embryos were enhanced by oligoglucosamine, suggesting that the mitosis in wheat embryo cells could be promoted by oligoglucosamine. The inhibition of DON on the growth of etiolated wheat seedlings and on the activation of the cell cycle in wheat embryo cells were relieved when the seeds were immersed in oligoglucosamine solution for 12 h before DON treatment. The results indicated that oligoglucosamine increased the hardiness to the poisoning of DON in wheat embryo cells. This might be the reason why such oligosaccharide elicits the resistance of plants to pathogen infection.
The activation of defense genes in tomato plants has been shown to be mediated by an octadecanoic acid-based signaling pathway in response to herbivore attack or other mechanical wounding. We report here that a tomato mutant (JL5) deficient in the activation of wound-inducible defense genes is also compromised in resistance toward the lepidopteran predator Manduca sexta (tobacco hornworm). Thus, we propose the name defenseless1 (def1) for the mutation in the JL5 line that mediates this altered defense response. In experiments designed to define the normal function of DEF1, we found that def1 plants are defective in defense gene signaling initiated by prosystemin overexpression in transgenic plants as well as by oligosaccharide (chitosan and polygalacturonide) and polypeptide (systemin) elicitors. Supplementation of plants through their cut stems with intermediates of the octadecanoid pathway indicates that def1 plants are affected in octadecanoid metabolism between the synthesis of hydroperoxylinolenic acid and 12-oxo-phytodienoic acid. Consistent with this defect, def1 plants are also compromised in their ability to accumulate jasmonic acid, the end product of the pathway, in response to wounding and the aforementioned elicitors. Taken together, these results show that octadecanoid metabolism plays an essential role in the transduction of upstream wound signals to the activation of antiherbivore plant defenses.
Oligochitosan was used as elicitor to treat tobacco leaves, and the concentrations of internal secretions and low molecular weight compounds were determined by high performance liquid chromatography with a coulometric array detector (HPLC-CAD). The CAD has 8 electrochemical detector cells and the cell potentials were maintained at -200, 300, 400, 500, 600, 700, 800, 850 mV, beginning with the first sensor in series. A Hypersil BDS C18 Chromatographic column (4.6 mm i.d. ×200 mm, 5 μm) was employed. The concentrations changed with the treating time by oligochitosan: jasmonic acid (JA) and gibberellic acid (GA) reached peak value after being treated for 6 h, whereas indoleacetic acid (IAA) did for 8 h. Some other compounds was observed as well during the treatment. They are believed to be low molecular weight compounds and subject to further investigations.
Affinity cross-linking of the plasma membrane fraction to an¹²⁵I-labeled chitin oligosaccharide led to the identification and characterization of an 85-kD, chitin binding protein in plasma membrane-enriched fractions from both suspension-cultured soybean cells and root tissue. Inhibition analysis indicated a binding preference for larger (i.e. degrees of polymerization = 8)N-acetylated chitin molecules with a 50% inhibition of initial activity value of approximately 50 nm.N-Acetyl-glucosamine and chitobiose showed no inhibitory effects at concentrations as high as 250 μm. It is noteworthy that the major lipo-chitin oligosaccharide Nod signal produced by Bradyrhizobium japonicum was also shown to be a competitive inhibitor of ligand binding. However, the binding site appeared to recognize the chitin portion of the Nod signal, and it is unlikely that this binding activity represents a specific Nod signal receptor. Chitooligosaccharide specificity for induction of medium alkalinization and the generation of reactive oxygen in suspension-cultured cells paralleled the binding activity. Taken together, the presence of the chitin binding protein in the plasma membrane fraction and the specificity and induction of a biological response upon ligand binding suggest a role for the protein as an initial response mechanism for chitin perception in soybean (Glycine max).
N-Acetylchitooligosaccharides (oligochitin, chitin oligosaccharides) of a specific size can act as potent elicitor signals for suspension-cultured rice cells as well as various plant cells which include many monocots and some dicots. We recently isolated and characterized a highly elicitor-active glucopentaose from the cell wall β-Glucan from rice blast disease fungus. The results indicated that rice and soybean cells recognize different structural units of fugal glucans as elicitor signals. Because this elicitor treatment can induce many defense reactions, it has been serving as an excellent model system for the study of the signal transduction cascade leading to the activation of defense-related genes. It is critically important to identify and characterize the receptor molecules which perceive the elicitor signal to clarify the whole signal transduction cascade. A 75 kDa chitin oligosaccharide binding protein in the plasma membrane of suspension-cultured rice cells was identified as a putative receptor for the elicitor and purified. Recent studies on the structure and function of the binding proteins for these oligosaccharide elicitors will provide a clue to understanding how these elicitors are perceived and transduced in rice and other plant cells and also how such recognition systems have evolved.
Pea (Pisum sativum L. cv Alcan) endocarp tissue challenged with an incompatible fungal pathogen, Fusarium solani f. sp. phaseoli or fungal elicitors results in the induction of pathogenesis-related (PR) genes and the accumulation of pisatin, a phytoalexin. Essentially the same response occurs in pea tissue exposed to DNA-specific agents that crosslink or intercalate DNA. In this study, the effects of DNA-damaging agents were assessed relative to the inducible expression of several pea PR genes: phenylalanine ammonia lyase, chalcone synthase, and DRR206. Mitomycin C and actinomycin D mimicked the biotic elicitors in enhancing the expression of all three PR genes. The activities of these PR gene promoters, isolated from different plants, were evaluated heterologously in transgenic tobacco. It is remarkable that β-glucuronidase expression was induced when plants containing the heterologous phenylalanine ammonia lyase, chalcone synthase, and DRR206 promoter-β-glucuronidase chimeric reporter genes were treated by DNA-damaging agents. Finally, cytological analyses indicated that many of these agents caused nuclear distortion and collapse of the treated pea cells. Yet we observed that cell death is not necessary for the induction of the PR gene promoters assessed in this study. Based on these observations and previously published results, we propose that DNA damage or the associated alteration of chromatin can signal the transcriptional activation of plant defense genes.
In suspension cultured cells of parsley (Petroselinum crispum), chitosan elicited a rapid deposition of the 1,3-ß-glucan callose on the cell wall and a slower formation of coumarins. With cells remaining in conditioned growth medium, fully N-deacetylated chitosans and partially N-acetylated chitosans were about equally active, the potency increased with the degree of polymerization up to several thousand and addition of reduced glutathione increased the sensitivity of the cells. These results indicate common initial events in the induction of callose and coumarin synthesis although two fully independent metabolic pathways are involved. When the cells were suspended in fresh growth medium, less chitosan was required, and fully N-deacetylated chitosan became the best callose elicitor.
Partially and fully deacetylated chitosan fragments and oligomers were compared for their potency to elicit formation of the 1.3-β-glucan callose in suspension-cultured cells and protoplasts of Catharanthus roseus (line 385). Chitosan oligomers induced little callose formation, while callose synthesis increased with the degree of polymerization of chitosan up to several thousand corresponding to a molecular mass near 10(6) Da. At a comparable degree of polymerization, partially N-acetylated chitosan fragments were less effective. Colloidal chitin and chitin oligomers induced only trace callose synthesis in protoplasts. These results indicate that the primary interaction involved the amino groups of chitosan and numerous negative charges at the surface of the plasma membrane with spacing in the nanometer range and occurring regularly over micrometer stretches. Charged phospholipid head-groups may fulfill these requirements. The resulting alteration of membrane fluidity may lead to the changes in ion transport known to be associated with the induction of callose formation.
A lectin specific for glucosamine oligomers has been purified by chitosan affinity chromatography from cultured cells of Rubus. The lectin, eluted by a glucosamine oligomer of degree of polymerization 4 in the presence of l-α-phosphatidylserine dipalmitoyl, was found by sodium dodecyl sulfate-polyacrylamide gel electroploresis to be homogeneous and to have a molecular weight of 67 kilodaltons; it could best bind the tetrasaccharide, as shown by ligand-blot processing. Data from kinetic-dependent enzyme-linked immunosorbent assays showed that the lectin has two apparent binding sites which better accommodate the tetrasaccharide and the hexasaccharide, respectively, of the glucosamineoligomer series. The affinity of the lectin for glucosamine oligomers was shown to decrease for chain lengths greater than six glucosaminyl residues.
As the study of coconut defense responses against pathogenic microorganisms is hampered by the absence of suitable model systems, we investigated if imbibition of coconut calli with chitosan could be used in vitro to simulate the molecular interactions that occur with pathogens. Our results showed that calli imbibition with 10mgmL−1 chitosan caused the accumulation of hydrogen peroxide, and stimulated a β-1,3-glucanase activity with an Rf near 0.1. In addition, in-gel kinase assay and specific immunoblotting showed that a ∼46kDa MAPK-like protein was activated shortly after elicitation, and remained in this state for at least 80min. Chitosan addition also differentially modified the expression of some genes, whose DNA sequence showed high similarities to receptor-like kinases (RLKs), Verticillium-like protein, and mitochondrial alternate oxidase 1b. Addition of salicylic acid to the calli also modified transcript abundance for these genes, while methyl jasmonate did not seem to influence their expression, implying that they could be involved in defense responses. These results strongly suggest that elicitation of coconut tissues cultivated in vitro constitutes a suitable alternative to characterize both biochemical and molecular interactions that occur between the coconut palm and its associated pathogens.
SUMMARY Binding to tobacco cells of oliogochitosan labeled with the fluorophore 2-aminoacidone (2-AMAC) was investigated using laser scanning confocal microscopy (LSCM). Production of NO in epidermal tobacco cells treated with oligochitosan was investigated by epider- mal strip bioassay and LSCM, using the cell-permeable fluorophore diaminofluorescein diacetate (DAF-2D). Binding of the labeled oligochitosan to cell walls and membranes of tobacco cells was directly observed by LSCM. Binding antagonist assays showed that unla- beled oligsaccharides apart from oligochitosn did not inhibit the observed binding of labeled oligochitosan to cell walls and membranes. Treatment of epidermal tobacco cells with oligochi- tosan resulted in a strong increase of intracellular NO. Oligochitosan and the NO donor SNP induced a de- fense reaction against Tobacco mosaic virus (TMV), in- creased PAL activity and elevated PAL mRNA level. Co-treatment of oligochitosan and NO (scavenger CP- TIO) blocked the inducing resistance indicating that the defense response induced by oligochitosan was con- nected with the NO pathway.
Chitosan oligomers are known elicitors of plant defence mechanisms. In this work, chitooligosaccharides of different degrees of polymerization and degrees of acetylation were prepared and characterized by matrix-assisted laser desorption ionization time-of-flight mass spectrometry. The effect of the degree of polymerization (DP), degree of acetylation and concentration of these chitooligosaccharides on defence activation in Arabidopsis thaliana suspension-cultured cells was studied. Our study results show that fully deacetylated chitooligosaccharides (chitosan oligomers) induce, depending on their DP and concentration, phenylalanine ammonia-lyase (PAL) activation, H2O2 synthesis and cell death in A. thaliana cell suspensions. The progressive reacetylation of the chitosan oligomer elicitors progressively impaired their ability to enhance H2O2 accumulation and cell death, but did not affect the activation of PAL.
Chitooligomers or chitooligosaccharides (COS) are elicitors that bind to the plasma membrane (PM) and elicit various defense responses. However, the PM-bound proteins involved in elicitor-mediated plant defense responses still remain widely unknown. In order to get more information about PM proteins involved in rice defense responses, we conducted PM proteomic analysis of the rice suspension cells elicited by COS. A total of 14 up- or downregulated protein spots were observed on 2-D gels of PM fractions at 12 h and 24 h after COS incubation. Of them, eight protein spots were successfully identified by MS (mass spectrography) and predicted to be associated to the PM and function in plant defense, including a putative PKN/PRK1 protein kinase, a putative pyruvate kinase isozyme G, a putative zinc finger protein, a putative MAR-binding protein MFP1, and a putative calcium-dependent protein kinase. Interestingly, a COS-induced pM5-like protein was identified for the first time in plants, which is a transmembrane nodal modulator in transforming growth factor-β (TGFβ) signaling in vertebrates. We also identified two members of a rice polyprotein family, which were up-regulated by COS. Our study would provide a starting point for functionality of PM proteins in the rice basal defense.
We investigated variations in the level and composition of volatiles emitted by tomato leaves at different ages. Our focus
also included their antifungal properties and responses to chitosan oligosaccharide. Based on leaf position, the release of
volatiles decreased over time. Young leaves produced high levels of C6-aldehyde, which is mainly composed of hexenal, while
the volatiles emitted by more mature leaves largely comprised terpenes, particularly β-phellandrene and caryophyllane. In
young upper leaves, the main components (up to 86% of the total) were hexenal, β-phellandrene, and caryophyllane. Their levels
decreased steadily over time, from 386.3μg g−1 fresh weight (FW) in young leaves to 113.2μg g−1 FW in old tissues. Volatiles emitted from young leaves exhibited the best antifungal activity against spore germination and
hyphal growth by Botrytis cinerea and Fusarium oxysporum. Leaves became more susceptible to oligosaccharide treatment with increasing age. When young tissues were exposed to chitosan,
we found declines in both the quantity of volatiles and their ability to inhibit fungal growth. Compared with the control,
the amount of volatiles from young tissues was 88.4% lower after such treatment. In contrast, contents of volatiles from old
and adult leaves were dramatically increased by chitosan oligosaccharide. Likewise, their inhibitory effect was significantly
enhanced. Therefore, our results suggest that these volatiles are responsible for antifungal activity and may play a role
in age-related resistance by tomato.
Low-molecular-weight water-soluble chitosan (5 kDa) obtained after enzymatic hydrolysis of native crab chitosan was shown to display an elicitor activity by inducing the local and systemic resistance of Solanum tuberosum potato and Lycopesicon esculentum tomato to Phytophthora infestans and nematodes, respectively. Chitosan induced the accumulation of phytoalexins in tissues of host plants; decreased the total content; changed the composition of free sterols producing adverse effects on infesters; activated chitinases, -glucanases, and lipoxygenases; and stimulated the generation of reactive oxygen species. The activation of protective mechanisms in plant tissues inhibited the growth of taxonomically different pathogens (parasitic fungus Phytophthora infestans and root knot nematode Meloidogyne incognita).
The mechanisms of induced resistance and susceptibility of potato (Solanum tuberosum L.) tubers to late blight agent (Phytophthora infestans Mont de Bary) were studied using an elicitor chitosan and an immunosuppressor laminarin. It was elucidated that treatment
of disks from potato tubers with chitosan resulted in salicyclic acid (SA) accumulation due to activation of benzoate-2-hydroxylase
and hydrolysis of SA conjugates. Such SA accumulation in potato tissues inhibited one of the antioxidant enzymes, catalase,
inducing an oxidative burst and resistance development. The mechanisms of induced susceptibility to the late blight causal
agent were studied using an unspecific immunosuppressor, laminarin, an analogue of natural specific suppressor of potato immune
responses, β-1,3,β-1,6-glucan. It was established that the development of immunosuppression in tissues treated with laminarin
did not affect the SA level in tissues. However, catalase sensitivity to SA reduced in laminarin-treated tissues, and the
enzyme activity increased. In its turn, this might result in the reduced level of hydrogen peroxide in the cells and, as a
sequence, in the increased potato susceptibility to late blight.
In this study, we examined the response(s) of rice (Oryza sativa L. japonica-type cv. Nipponbare) seedling leaves treated with a fungal elicitor chitosan (CT). Small brownish necrotic spots (streaks) appeared in the interveinal regions on the leaf surface after treatment by 0.1% CT, over the cut control. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis and immunoblot analysis further revealed strong induction of ascorbate peroxidase, and changes in “phytocystatins” (cysteine proteinase inhibitors). Using two-dimensional polyacrylamide gel electrophoresis, evidence is provided for the accumulation of two major classes of pathogenesis-related (PR) proteins, namely OsPR5 and OsPR10 in the leaves. In parallel, northern analyses revealed potent accumulation of the OsPR5 and OsPR10 mRNAs; a time- and dose-dependent expression, and a requirement for de novo protein synthesis was observed. Furthermore, CT-elicited changes were also accompanied by production of anti-fungal phytoalexins, the flavonoid sakuranetin and the diterpenoid lactone momilactone A, as determined by liquid chromatography-mass spectrometry/mass spectrometry analysis. Present results reveal for the first time the potency of CT in initiating multiple events linked with defense/stress response(s) in the leaves of whole rice plants.
The objective of this study was to evaluate the antifungal properties of chitosan and to assess its role in the protection of tomato and grape plants against Colletotrichum sp. isolated from infected tissues of Dracaena sanderiana. The isolate was tested in vitro using PDA amended with five concentrations of chitosan (0, 1, 1.5, 2, 2.5%). Chitosan significantly (P < 0.05) inhibited the radial growth of this fungus, with a marked effect at the three highest concentrations, after 7 d incubation. The effective concentration that reduced the radial growth to 50% (EC50) was 2.28%. Tomato fruits and single berries treated with aqueous solutions of 1.0 and 2.5% (w/v) chitosan were artificially inoculated with Colletotrichum sp. and incubated at 4 and 24 °C. Lesion diameters were recorded 7 and 10 d after inoculation. After 10 d at 24 °C, chitosan significantly (P < 0.05) reduced the lesion size of tomato fruits treated with 1.0 and 2.5%. Lesion diameter on pre-treated berries was also significantly reduced at 24 °C. However, no differences were observed between the chitosan concentrations and the corresponding controls at 4 °C; no lesions developed on berries at either 7 or 10 d after inoculation and although lesion size on tomato fruits was smaller for all treatments when stored at 4 °C, there were no treatment differences.
Chitosans which had been: (1) derived chemically from the chitin of fungal cell walls, (2) accumulated in Fusarium solani/pea interactions or (3) released from chitinase and β-glucanase digestion of sporelings, were used to determine if these fungal polymers had the biological activity of the chitosan chemically derived from crustaceans. The biological activity of the cell wall chitin-derived chitosan from F. solani f. sp. phaseoli mimicked that of shrimp chitosan and was somewhat superior to that from f. sp. pisi. F. solani f. sp. phaseoli chitosans inhibited germination of F. solani macroconidia at concentrations as low as 8 μg ml−1. 100 μg ml−1 of this chitosan provided protection against F. solani f. sp. pisi in pea pod tissue for periods of at least 5 days while 10 μg ml−1 could only maintain resistance for up to 3 days. In comparisons of chitosan-like oligomers released from the ff. sp. pisi and phaseoli, greater proportions of [3H]-N-acetylglucosamine labelled chitosan fraction (heptamer or larger) could be recovered both from f. sp. phaseoli/pea interactions and from f. sp. phaseoli germlings in contact with a chitinase and β-glucanase-rich basic pea protein fraction. The results indicate that the chitosan heptamer-plus fraction readily recovered from these plant-fungal interactions is able to function as a major biological signal in pea/-Fusarium interactions while the chitosan pentamer which preferentially accumulates in f. sp. pisi had less detectable biological activity.
Seeds of rice (Oryza sativa L.) were treated with chitosan and hydrolyzed chitosan at 100, 500 and 1000 mg L−1. After 18 days of germination, spore suspension of Pyricularia grisea was applied. The enzyme activity of phenylalanine ammonia-lyase, β-1-3-glucanase, chitinase and chitosanase in leaves of rice seedlings was evaluated after 24, 72, 120 and 168 h of inoculation. Blast affected area (%) was evaluated 7 and 14 days after spraying spore suspension. Chitosan performance to elicit defense response induction was associated with the concentration and type of chitosan. The activity of most of the enzymes tested was induced in leaves of treated seeds with chitosan and hydrolyzed chitosan at 1000 and 500 mg L−1, respectively. The highest enzyme activities were observed with hydrolyzed chitosan after 72 h however, compared to chitosan, the activity was not maintained during the entire post-inoculation period. The highest control (0 = no lesions) of P. grisea in rice seedlings was observed at 1000 mg L−1 in both chitosan and hydrolyzed chitosan treated leaves. Symptoms of infection by P. grisea were evident after 14 days evaluation date, but according to the standard scale proposed by the International Rice Research Institute, these symptoms fell into the resistance category of blast diseases.
Changes in phenolic metabolism and lignin deposition have been studied in roots of tomato plants after elicitation with four elicitors which are Fusarium mycelium extract (FME), chitosan (CHT), Fusarium culture filtrate (FCF) and Trichoderma mycelium extract (TME). Most profound effect of elicitors was observed on ferulic acid among the phenolic compounds. After 24 h elicitation, the increase in ferulic acid content of root cell wall was 3.71 and 3.30 times by FME and CHT, respectively. The increase of 4-hydroxybenzoic acid was 2.71 and 2.16 times by these two elicitors. The level of 4-coumaric acid was little more than double by these two elicitors after 24 h elicitation. Most pronounced increase in lignin synthesis was also effected by FME followed by CHT. Lignin deposition in the root cell wall was increased 3.6, 5.4 and 7.1 times by FME during 12, 24 and 36 h after elicitation, respectively. Similarly, CHT increased lignin deposition by 2.8, 5.1 and 6.8 times at 12, 24 and 36 h after elicitation, respectively. FCF and TME also increased lignin deposition significantly in the cell walls of tomato roots during the above time periods of elicitation. Activity of phenylalanine ammonia lyase reached highest level at 24 h post elicitation under the influence of the elicitors. Peroxidase activity registered a sharp increase at 24 h post elicitation. Markedly increased level of polyphenol oxidase activity was found at 12 h post elicitation. Cinnamyl alcohol dehydrogenase activity was observed to reach highest level at 48 h post elicitation. Cell wall strengthening, through the deposition of lignin, preceded by the induction of the synthesizing enzymes appears to play an important role in the defense response of Lycopersicon esculentum in reaction to elicitors, including one derived from Fusarium oxysporum f. sp. lycopersici, the causal organism of Fusarium wilt of tomato.
Chitin is the second most important natural polymer in the world. The main sources exploited are two marine crustaceans, shrimp and crabs. Our objective is to appraise the state of the art concerning this polysaccharide: its morphology in the native solid state, methods of identification and characterization and chemical modifications, as well as the difficulties in utilizing and processing it for selected applications. We note the important work of P. Austin, S. Tokura and S. Hirano, who have contributed to the applications development of chitin, especially in fiber form. Then, we discuss chitosan, the most important derivative of chitin, outlining the best techniques to characterize it and the main problems encountered in its utilization. Chitosan, which is soluble in acidic aqueous media, is used in many applications (food, cosmetics, biomedical and pharmaceutical applications). We briefly describe the chemical modifications of chitosan—an area in which a variety of syntheses have been proposed tentatively, but are not yet developed on an industrial scale. This review emphasizes recent papers on the high value-added applications of these materials in medicine and cosmetics.
The non-host disease resistance response of cuticle-free pea endocarp tissue against Fusarium solani f. sp. phaseoli, a bean pathogen, is a synchronous cellular response that completely inhibits the challenging fungal growth within 6 h. This tissue becomes susceptible to the true pathogen, F. solani f. sp. pisi, within 18 h. Previous research indicated that there is an early effect by both pathogens on pea chromatin possibly via the architectural transcription factor, HMG A. HMG A binds with AT-rich regions of the pea DRR206 gene (a PR gene) promoter. The total PR gene-based defense response is activated by three eliciting agents, Fsph DNase, chitosan oligomers and inhibitors of phosphatase such as calyculin A. This report monitors the presence of HMG A and histone and their phosphorylation and ubiquitination, both within the total cytoplasm and in association with isolated chromatin. Inoculation results in a diminution of both HMG A and histones H2A/H2B within 5 h, being more extensive in the susceptible interaction. The detectable phosphorylated HMG A and some accompanying nuclear proteins are diminished within 4 h after pathogen challenge. Changes in the molecular weight of the nuclear components were ELISA-monitored with anti-HMG A, anti-histone H2A/H2B and anti-ubiquitin antisera and indicated that some fungal-caused global changes in chromatin occur via ubiquitin complexing. These modifications of the pea's nuclear proteins could have major transcriptional-related roles in disease resistance since they are temporally associated with the onset of PR gene activation.
Oligochitosan was applied by spraying it on tobacco leaves for inhibition of tobacco mosaic virus (TMV). The maximum inhibition of TMV by oligochitosan was observed when inoculation occurred at 24 h after spraying 50 μg ml−1 oligochitosan. The production of H2O2 and NO in epidermal tobacco cells induced by oligochitosan was investigated by epidermal strip bioassay and LSCM, using cell permeable fluorophore diaminofluorescein diacetate (DAF-2D) and 2′,7′-dichlorofluorescin diacetate (H2DCF-DA), respectively. Epidermal tobacco cells treated with oligochitosan resulted in a strong increase of intracellular NO and H2O2. Oligochitosan and NO donor sodium nitroprusside (SNP) induced the defense reaction against tobacco mosaic virus (TMV), and increased phenylalanine ammonia-lyase (PAL) activity. Co-treatment of the tobacco cells with oligochitosan and NO scavenger CPTIO blocked the inducing resistance. The results indicated that the defense response induced by oligochitosan was connected with NO pathway.
Oligochitosan (OC) can regulate plant defense responses in many aspects, but the basic signal transduction pathway is still unclear. In this study, we used transgenic (TG) tobacco (Nicotiana Tabacum var. Samsun NN) as plant material whose oligochitosan induced protein kinase (OIPK) gene was inhibited by antisense transformation, to study the role of OIPK in tobacco defense reactions. The results showed that OIPK could increase tobacco resistance against tobacco mosaic virus (TMV), in that wild-type (WT) tobacco showed longer lesion appearance time, higher lesion inhibition ratio, smaller average final lesion diameter and lower average final lesion area percent to whole leaf area. It led us to analyze some pathogenesis related (PR) enzymes' activities and mRNA level, which played roles in tobacco resistance against TMV. We found that phenylalanine ammonia-lyase (PAL) and peroxidase (POD) activities were positively related to OIPK, but not polyphenol oxidase (PPO). It was also demonstrated that OIPK mRNA could be induced by OC, wound and TMV infection. In addition, OIPK could up-regulated three PR genes, PAL, chitinase (CHI) and β-1, 3-glucanase (GLU) mRNA level to different extent. Taken together, these results implied that OIPK could function in tobacco resistance against both biotic and abiotic stress, possibly via various PR proteins.
We have measured the susceptibility of carrots to the storage pathogen Sclerotinia sclerotiorum after roots were treated postharvest with a 0.2% (w/v) chitosan hydrolysate (number average degree of polymerisation = 7) prepared using Streptomyces N-174 chitosanase. Whereas the hydrolysate did not affect radial growth of S. sclerotiorum colonies on potato dextrose agar plates, it reduced the frequency and size of rot compared to untreated controls when applied to carrots 3 days before inoculation with S. sclerotiorum. When carrots were treated at time zero with either chitosan hydrolysate or high molecular weight chitosan then inoculated at intervals over the next 5 days, there was a decline in Sclerotinia infection, with the hydrolysate showing a greater effect than the high molecular weight chitosan. Our results suggest that the chitosan treatments induced host resistance to the pathogens.
Chitosan (CHT) is a natural compound able to activate the plant own defence machinery against pathogen attacks and to reduce both transpiration and stomatal opening when applied as foliar spray. The data here reported show that CHT-induced antitranspirant activity in bean plants is mediated by ABA, whose level raised over threefold in treated leaves, 24 h after foliar spraying. This is thought to induce partial stomatal closure via a H2O2-mediated process, as confirmed by scanning electron microscopy (SEM) and histo-cytochemistry, and, in turn, a decrease of stomatal conductance to water vapor (Gw) and transpiration rate (E), assessed by gas exchange measurements. The relatively high internal CO2 concentration (Ci) values, suggest the occurrence of a slight decrease in carboxylation efficiency after CHT treatment, which however did not prevail over stomatal limitations. The intrinsic water use efficiency (WUEi) of CHT treated plants was not statistically different from controls and the maximal photochemical efficiency (Fv/Fm) of PSII was not affected. Moreover, CHT determined a stimulation of the xanthophyll cycle towards de-epoxidation state. On the whole, these results, besides confirming the effectiveness of CHT in reducing plant transpiration, prove that the mechanism underlying this activity differs from that showed by the commercial antitranspirant Vapor Gard® (VP). In fact, the efficacy of the latter is based on the formation of a thin antitranspirant film over the leaf and not on the reduction of stomatal opening. Finally, suggestions for possible use of the two antitranspirants in different environmental conditions are discussed.
Pythium aphanidermatum (Edson) Fitzp., causing root and crown rot in cucumber, was successfully managed by Lysobacter enzymogenes strain 3.1T8. Greenhouse experiments were performed with cucumber plants grown in rockwool blocks up to 5 weeks with a recirculated nutrient solution. Application of L. enzymogenes 3.1T8 in combination with chitosan (the deacetylated derivative of chitin) reduced the number of diseased plants by 50-100% in four independent experiments relative to the Pythium control. Application of chitosan or the bacterial inoculant alone was not effective. Washed bacterial cells plus chitosan inhibited Pythium-induced disease, but the supernatant without bacterial cells combined with chitosan was not effective. The most effective and convenient type of commercially available chitosan was selected. Chitosan disappeared from the hydroponic system within 24 h after application, which we attribute to enzyme expression of L enzymogenes 3.1T8 induced by the exposure to chitosan. Plate counts of the nutrient solution on a general bacterial medium showed the dominance of the inoculated strain, and an increased bacterial population growing on chitin and chitosan as single carbon source. The population density of L enzymogenes 3.1T8 on the cucumber roots was investigated with a strain specific real-time TaqMan PCR. Highest chitosan concentrations applied (0.1 and 0.03 g/plant) resulted in the highest numbers of L. enzymogenes 3.1T8 present on roots; i.e. 10(8)-10(9) cells/g root. Substantially higher numbers of bacterial cells were observed by scanning electron microscopy after application of chitosan; no morphological or other qualitative differences were found. The results indicate that addition of chitosan enhanced the biocontrol efficacy of L. enzymogenes 3.1T8; either chitosan serves as C- and N-source for the antagonist, induces antagonistic gene expression, or both.