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Chitosan and chitin oligomers increase phenylalanine ammoni-lyase and tyrosine ammonia-lyase activities in soybean leaves
Abstract
Phenylalanine ammonia-lyase (PAL, EC 4.3.1.5) and tyrosine ammonia-lyase (TAL, 4.3.1.), the key enzymes of the phenylpropanoid pathway, are inducible in response to biotic (such as chitin from fungal cell walls) and abiotic cues. Application of chitin and chitosan to soybean leaf tissues caused increased activity of PAL and TAL enzymes. The elevation of enzyme activity was dependent on the chain length of the oligomers and time after treatment. The hexamer of chitin and pentamer of chitosan produced the maximum activities at 36 h after treatment as compared to controls. Total phenolic content of soybean leaves increased following chitosan and chitin oligomer treatments, showing a positive correlation between enzyme activity and total phenolic content.
... Chitosan is essentially a stress-stimulating factor for plants; there is also evidence of the negative impact of this polymer on their development. It has been shown that the efficiency of chitosan depends on its molecular weight, chemical structure (degrees of deacetylation, polymerization, and protonation), source of chitin, and polymer concentration [41][42][43][44]. In our study, we used low-molecular-weight chitosan hydrolysate obtained from crab shells. ...
... The other study with Arabidopsis thaliana [64] shows that seedling growth slowed under the influence of a 0.1 mg/mL chitosan solution. Molecular weight, chemical structure, and chitin source are influential factors in processing results [42]. ...
... The total phenolic content and PAL activity in soybean leaves increased after chitosan treatment, and a correlation between enzyme activity and total phenolic content was observed. The highest PAL activity in leaves was observed after 36 h of treatment, decreasing at 48 h [42]. In addition, in hydroponic tomatoes, the presence of chitosan in the culture medium increased the total phenolic content and PAL activity in roots after 48 h [30]. ...
The latest research has shown that chitosan acts as a growth stimulator and elicitor in plants, including resistance to biotic and abiotic factors. However, increasing concentrations could possibly make chitosan a source of stress for plants. In this study, we investigated the effect of low-molecular-weight chitosan hydrolysate on the root development of tomato (Solanum lycoperscum) cultivars Red Cherry, Lel, and Tytan. The growth rate change, together with total phenolic content, phenylalanine ammonia-lyase (PAL) activity, and gene expression, were studied in relation to tomatoes. High concentrations of chitosan negatively affect the growth of tomato seedlings and contribute to changes in the tropism of the seedling roots. After the addition of chitosan hydrolysate, the PAL activity and the total phenolic content decreased 24 h later. PAL is a key enzyme in the biosynthesis of many plant stress factors. An analysis of the tomato PAL gene family was carried out. The SlPAL gene expression in the seedlings of cv. Cherry increased 1.5 times after 48 h, while in cv. Lel, the expression stably decreased in the presence of chitosan. The obtained results are supposed to aid our understanding of the mechanisms underlying the effects of chitosan on plant development and further its successful application in agriculture as well as in research on plant stress.
... The transformation was based on the difference in absorbance measurements before and after incubation. The PAL activity was expressed at U − nM trans-cinnamic acid/min/mg protein [41,42]. ...
... The transformation was based on the difference in absorbance measurements before and after incubation. The TAL activity was expressed at U − nM coumaric acid/min/mg protein [41,42]. ...
... PR proteins with β-glucanase (PR2 and PR5 group) and chitinase (PR3, PR4, PR8, and PR11 group) activity were produced in plant tissues after pathogen infection or induction by elicitors of plant resistance [41]. These enzymatic activities were detected in fungal cultures supplemented with fragments of the pathogen's cell wall [12,13,26]. ...
Laetiporus sulphureus (Bull.: Fr.) Murrill is an arboreal species of the large-fruited Basidiomycota fungus from the Polyporales, family Laetiporaceae. The cell wall of this fungus is the source of many bioactive polymer compounds, including (1→3)-α-D-glucans. (1→3)-α-D-glucans can be hydrolyzed to shorter compounds, (1→3)-α-D-glucooligosaccharides (GOS), with different degrees of polymerization (DP). The use of GOS obtained from L. sulphureus (1→3)-α-D-glucans, as an elicitor of plant resistance, may be important for biological protection used in sustainable agriculture. In the presented study, GOS influenced the activity of antioxidant enzymes (Catalase−CAT, Ascorbate Peroxidase−APX, Guaiacol Peroxidase−GPX, and Superoxide Dismutase−SOD), lignin and flavonoids producing phenylpropanoids pathways (Phenylalanine Ammonia-Lyase−PAL and Tyrosine Ammonia-Lyase−TAL), and pathogen-related proteins (with Glucanase−GLUC and Chitinase−CHIT activity) in wheat (Triticum aestivum L.) seedling tissues. Other than that, the application of GOS increased the fresh weight of wheat stems and roots by 1.5–2-times, compared to the water control. The GOS at a concentration of 0.05% most strongly increased the activity of APX and GPX, where a 2-fold (up to 6000 U) and a 3-fold (up to 180 U) increase in enzymatic activity in wheat stems was observed, compared to the control. Simultaneously, 0.1% GOS significantly increased the activity of PAL (80 U in stems and 50 U in roots) and TAL (60 U in stems and 50 U in roots), where a 4–5-fold increase in enzymatic activity was observed, both in comparison to the water control and commercial elicitors (chitosan−CHI and laminarin−LAM). No effect of GOS on GLUC activity was observed, but a 1.5–2-fold increase in CHIT activity in plant tissues was noted. The complexity of the influence of GOS on the level of marker enzymes indicates the potential of their application in agriculture. This work is the first report of the successful use of (1→3)-α-D-glucooligosaccharides as an elicitor inducing resistance in the cereal plant (wheat).
... An increase in the Chl content in plants has been confirmed by Dzung et al. [70] and Salachna and Zawadzińska [71] who reported that spraying of coffee and corm seedlings with Chs solutions enhanced the content of Chl and carotenoids in leaves in comparison to the control. Related study by Khan et al. [72] reported that the application of Chs increased photosynthesis in the leaves of soybean. Moreover, foliar application of Chs enhanced the Chl content under Ni stress [69] and Cd [73]. ...
... According to Romanazzi et al. [95], Chs elevated PAL, which triggered the pathway leading to the synthesis of phenol. Related study by Khan et al. [72] showed transcriptional activation of gene encoding PAL was induced by Chs. The negative effects of MDA on the cell membrane can be reduced by the combined action of CAT, POX, and PAL. ...
In the course of their life, plants face a multitude of environmental anomaly that affects their growth and production. In recent decades, lead (Pb) gained an increasing attention as it is among the most significant contaminants in the environment. Therefore, in this study the effects of Pb concentrations (0, 50 and 100 ppm) on Vicia faba plants and attempts to alleviate this stress using chitosan (Chs; 0 and 0.1%) were performed. The results validated that with increasing Pb concentrations, a decline in growth, pigments and protein contents was observed. In the same time, a significant upsurge in the stress markers, both malondialdehyde (MDA) and H2O2, was observed under Pb stress. Nonetheless, foliar spraying with Chs improves the faba bean growth, pigment fractions, protein, carbohydrates, reduces MDA and H2O2 contents and decreases Pb concentrations under Pb stress. Pb mitigation effects by Chs are probably related with the activity of antioxidant enzymes, phenylalanine ammonia lyase (PAL) and proline. The application of Chs enhanced the activities of peroxidase, catalase and PAL by 25.77, 17.71 and 20.07%, respectively at 100 ppm Pb compared to their control. Plant genomic material exhibits significant molecular polymorphism, with an average polymorphism of 91.66% across all primers. To assess the genetic distance created among treatments, the dendrogram was constructed and the results of the similarity index ranged from 0.75 to 0.95, indicating genetic divergence. Our research offers a thorough comprehension of the role of Chs in lessening the oxidative stress, which will encourage the use of Chs in agricultural plant protection.
... and TAL (EC 4.3.1.25) was evaluated using a method described by Khan et al. (2003). Extraction was carried out by homogenizing 1 g of kiwifruit pulp with 10 mL of ice-cool Tris-HCl buffer (50 mM, pH 8.5) comprising of 5% (w/v) polyvinylpolypyrrolidone (PVPP) and 14.4 mM β-mercaptoethanol. ...
... Furthermore, the correlation analysis indicates that the accumulation of phenolic compounds is associated with the enzymatic activity of PAL and TAL. These findings are corroborated by those reported by Khan et al. (2003). Furthermore, the inverse relationship between AA and AO suggests that AO has an influence in the degradation of AA (Jiang et al., 2018). ...
Kiwifruit exhibits a climacteric ripening pattern and has as an extremely perishable nature. Considering that high perishability leads to a loss in antioxidants and overall nutritional quality. This study aimed to examine the efficacy of enhanced freshness formulation (EFF), a hexanal-based formulation containing antioxidants such as geraniol, α-tocopherol and ascorbic acid, on maintaining the bioactive compounds of gold kiwifruit (cv. ‘Y368’) harvested at two maturity stages. Kiwifruits were treated with three treatments, namely, control (untreated fruit), 0.01 and 0.02% (v/v) EFF. Fruits were treated with 8 weeks of cold storage at 0°C and 90% relative humidity, then transferred to 20°C for 8 days. Three bioactive compounds (ascorbic acid, total phenolics and flavonoids), antioxidant capacities using DPPH and FRAP assays, polyphenol oxidase, ascorbate oxidase, phenylalanine and tyrosine ammonia lyase enzyme activities were evaluated. The results showed that EFF significantly ( p < 0.05) influenced bioactive compounds, antioxidant capacities and the activity of enzymes involved in the synthesis and oxidation of bioactive compounds. The maturity stage significantly influenced the content of bioactive compounds. Later harvested kiwifruit had greater content of bioactive compounds, compared to earlier harvested kiwifruit. The total phenolic content was 0.77, 1.09 and 1.22 mg GAE g ⁻¹ FW for control, 0.01 and 0.02% EFF, respectively. The FRAP antioxidant concentration was 0.76, 0.91 and 0.96 μmol Fe (II) g ⁻¹ FW for control, 0.01 and 0.02% EFF. The findings illustrate the capacity of EFF to optimize bioactive compounds and storability of kiwifruit during postharvest storage.
... Nevertheless, PAL is the most occurs in plants [60], while TAL enzyme is commonly found in Gramineae such as wheat and maize [62][63][64][65]. Recently, TAL has been detected in other plants such as orchids, strawberry fruits, and leaves, ginger and soybean leave in response to biotic and abiotic stresses [61,[66][67][68]. As reported by Khan et al., the treatment of soybean by chitin and chitosan oligomers significantly induced the PAL, TAL, and phenolic compounds in leaf tissues, which the specific activity of TAL was lower compared to PAL [67]. ...
... Recently, TAL has been detected in other plants such as orchids, strawberry fruits, and leaves, ginger and soybean leave in response to biotic and abiotic stresses [61,[66][67][68]. As reported by Khan et al., the treatment of soybean by chitin and chitosan oligomers significantly induced the PAL, TAL, and phenolic compounds in leaf tissues, which the specific activity of TAL was lower compared to PAL [67]. ...
This study aims to assess for the first time the ability of marine polysaccharides and their derivatives to stimulate natural defenses in olive tree leaves. Alginates, ALSM, and ALCM were isolated from the brown algae Sargassum muticum and Cystoseira myriophylloides, respectively. The OASM and OACM fractions were obtained after radical depolymerization of ALSM and ALCM, respectively. Three sulfated polysaccharides, arabinogalactans (AGB and AGP) and fucoidans (FUCCM) were extracted from the green alga Codium decorticatum and the brown seaweed C. myriophylloides, respectively. The extraction yield of different extracts was in the range of 0.82–32% and the average molecular weight (Mw) varied from 3000 Da to 2173 kDa. The M/G ratios of ALSM and ALCM were 0.87 and 1.12, respectively. FUCCM contained 53% of fucose and 12.83% of sulfates. The AGB and AGP fractions were characterized by the presence of a high degree of sulfation and protein (12–23% (w/w)) and were composed mainly of galactose, glucose, and arabinose. The aqueous saccharide solutions were applied to the leaf discs of the olive tree at 0.5 g/L, 1 g/L, and 2 g/L, for 24 h. These molecules triggered defense responses, by showing a differential capacity to induce the activity of the phenylalanine and tyrosine ammonia-lyase (TAL and PAL), polyphenols, and lignin contents in the leaves of the olive tree. Alginates and their derivatives as well as arabinogalactans exhibited an important induction of TAL activity compared to the PAL. The sulfated polysaccharides were more effective compared to the unsulfated polysaccharides (alginates) which were active at a low concentration. The optimum concentration for most of the studied elicitors was 2 g/L. These results suggest the valorization of these molecules derived from marine biomass as inducers of natural defenses of the olive tree to protect against phytopathogens in the context of sustainable development.
... Activities of antioxidant enzymes: SOD, CAT, APX and GPX were measured according to Garcıá-Limones et al. (2002) and Hanaka et al. (2019a). Additionally, activities of defence-related enzymes: phenylalanine ammonia-lyase (PAL), tyrosine ammonia-lyase (TAL) (Khan et al., 2003;Patel et al., 2017), and β-1, 3-glucanase (GLU) (Alfonso et al., 1992;Hope and Burns, 1987) were assigned. All the above experiments were conducted with usage of protein assays (Bradford, 1976). ...
... We proved that the reduced content of TPC and TFC was in most cases connected to reduction of PAL activity as was also demonstrated by Tassoni et al. (2012). Similarly to the data presented by Khan et al. (2003), our results show that PAL activity stayed higher than TAL and their activities were correlated with each other. Both of the above enzymes provide molecules for synthesis of secondary metabolites. ...
Copper stress in the presence of exogenous methyl jasmonate and Serratia plymuthica in a complete trifactorial design with copper (0, 50 µM), methyl jasmonate (0, 1, 10 µM) and Serratia plymuthica (without and with inoculation) was studied on the physiological parameters of Phaseolus coccineus. Copper application reduced biomass and allantoin content, but increased chlorophyll and carotenoids content as well as catalase and peroxidases activities. Jasmonate did not modify biomass and organic acids levels under copper treatment, but additional inoculation elevated biomass and content of tartrate, malate and succinate. Jasmonate used alone or in combination with bacteria increased superoxide dismutase activity in copper application. With copper, allantoin content elevated at lower jasmonate concentration, but with additional inoculation – at higher jasmonate concentration. Under copper stress, inoculation resulted in higher accumulation of tartrate, malate and citrate contents in roots, which corresponded with lower allantoin concentration in roots. Combined with copper, inoculation reduced catalase and guaiacol peroxidase activities, whereas organic acids content was higher. Under metal stress, with bacteria, jasmonate reduced phenolics content, elevated superoxide dismutase and guaiacol peroxidase activities. The data indicate that jasmonate and S. plymuthica affected most physiological parameters of P. coccineus grown with copper and revealed some effect on biomass.
... Supernatant fractions were assayed for maximal extractable activities of glutathione peroxidase (GPX) as described by Nagalakshmi and Prasad (2001) and monodehydroascorbate reductase (MDAHR) as described by Jiang and Zhang (2001). Glutathione-S transferase (GST) was measured as described by Habig et al. (1974), and guaiacol peroxidase (POD) was determined by the method of Khan et al. (2003). ...
... Decreases in the abundance of PAL, a key enzyme involved in phenylpropanoid pathway catalysing the conversion of L-phenylalanine to trans-cinnamic acid and ammonia (Khan et al., 2003), were observed in rice leaves grown on high ammonium (Figure 8a; Table S3). While the decreased abundance of PAL might suggest that this was a strategy to limit ammonia release in rice leaves, it is also likely to limit the synthesis of secondary metabolites. ...
Abstract Urea‐based fertilizers are commonly used in the agricultural rice production. Urea produces gaseous ammonia upon contact with plants and soil. Although rice is considered to be a relatively ammonium‐tolerant crop, urea fertilization can have a negative impact on seedling establishment because of tissue ammonia accumulation. We investigated the molecular/genetic regulation of ammonia tolerance in rice using a multidisciplinary approach consisting of high‐resolution LC‐MS/MS analysis and bioinformatics, together with plant molecular physiology and biochemistry. Growth with 10 or 80 mM NH4Cl led to an inhibition of photosynthesis and ROS accumulation. Proteomic analysis revealed changes in the levels of 266 proteins, which function in translation and protein metabolism, amino acid and carbon metabolism/transport, antioxidant and redox metabolism. The abundance of the transcripts encoding these proteins was increased under high ammonium. Data are presented showing that ammonia‐induced changes in metabolism are linked to a strong antioxidant response but little change in secondary metabolism.
... Thus, the interaction effect of different concentrations and treatment intervals of chitosan were investigated to retest this output in I. amara (Fig. 3c). Based on the evidence, Khan et al. (2003) also proved an about 50% augmentation in the total phenol amount in the soybean plants following chitosan treatment, displaying a positive correlation between PAL activity and the total phenol content. Considering that PAL is a vital enzyme in the phenylpropanoid biosynthetic pathway, it seems that its overactivity resulted in more phenol accumulations in chitosantreated I. amara (Khan et al. 2003). ...
... Based on the evidence, Khan et al. (2003) also proved an about 50% augmentation in the total phenol amount in the soybean plants following chitosan treatment, displaying a positive correlation between PAL activity and the total phenol content. Considering that PAL is a vital enzyme in the phenylpropanoid biosynthetic pathway, it seems that its overactivity resulted in more phenol accumulations in chitosantreated I. amara (Khan et al. 2003). According to our data, the contents of the total phenolics, avonoids, avonol, MDA, and anthocyanins in chitosan-treated cells on the 12-16th day (T2) were signi cantly higher than those of cells treated with chitosan on 8-12th elicitation (T1). ...
Iberis amara L. medicinal herb is well-known for having pharmacological values although its use has been challenged by the low levels of secondary metabolites. To address this issue, this study focused on evaluating the effect of explant, photoperiod, and plant growth regulators (PGRs) to find the optimum medium for inducing callus and establishing cell suspension in I. amara , followed by investigating the chitosan effect on some secondary metabolites. From our observations, the optimum condition for induced callus was achieved from the leaf explants in Murashige and Skoog (MS) media completed with 3 mg L − 1 6-benzylaminopurine(BAP) and 1 mgL − 1 1-naphthalene acetic acid(NAA) under 16-h light/8-h dark photoperiod. The MS enhanced with 3 mgL − 1 BAP, 1 mg L − 1 NAA, and 2% (w/v) sucrose appeared to be optimum conditions for suspension establishment. Thus, the cells were exposed to different concentrations of chitosan (200, 100, 50, and 0 mg L − 1 ) in their exponential growth stage from day 8 to 12 and day 12 to 16 following sub-cultures (T1) and sub-cultures (T2), respectively. The results showed that the 50 mgL − 1 chitosan significantly improved the total phenol, flavonoid, flavonol, and anthocyanin content in the I. amara in a dose-dependent manner. The highest malondialdehyde (MDA) amount, as a result of lipid peroxidation, was observed under the 200 ppm chitosan elicitation. Overall, these novel findings demonstrated the possibility of applying the cell suspension of I. amara treated with chitosan as a helpful approach for improving synthesizing phenolic compounds under controlled and sterile conditions without genetic modifications in medicinal herbs.
... At the first trifoliate stage, two weeks after planting, the seedlings were used for an experiment with technical grade chitin azure, a chitinase substrate (Sigma-Aldrich, cat# C3020). A modified stem-cut method was used to administer the chitin treatment 28 . For each genotype, nine seedlings were treated with chitin and nine were with buffer in each experiment. ...
Overexpression of Glycine max disease resistant 1 (GmDR1) exhibits broad-spectrum resistance against Fusarium virguliforme, Heterodera glycines (soybean cyst nematode), Tetranychus urticae (Koch) (spider mites), and Aphis glycines Matsumura (soybean aphids) in soybean. To understand the mechanisms of broad-spectrum immunity mediated by GmDR1, the transcriptomes of a strong and a weak GmDR1-overexpressor following treatment with chitin, a pathogen- and pest-associated molecular pattern (PAMP) common to these organisms, were investigated. The strong and weak GmDR1-overexpressors exhibited altered expression of 6098 and 992 genes, respectively, as compared to the nontransgenic control following chitin treatment. However, only 192 chitin- and 115 buffer-responsive genes exhibited over two-fold changes in expression levels in both strong and weak GmDR1-overexpressors as compared to the control. MapMan analysis of the 192 chitin-responsive genes revealed 64 biotic stress-related genes, of which 53 were induced and 11 repressed as compared to the control. The 53 chitin-induced genes include nine genes that encode receptor kinases, 13 encode nucleotide-binding leucine-rich repeat (NLR) receptor proteins, seven encode WRKY transcription factors, four ethylene response factors, and three MYB-like transcription factors. Investigation of a subset of these genes revealed three receptor protein kinases, seven NLR proteins, and one WRKY transcription factor genes that are induced following F. virguliforme and H. glycines infection. The integral plasma membrane GmDR1 protein most likely recognizes PAMPs including chitin and activates transcription of genes encoding receptor kinases, NLR proteins and defense-related genes. GmDR1 could be a pattern recognition receptor that regulates the expression of several NLRs for expression of PAMP-triggered immunity and/or priming the effector triggered immunity.
... During germination, the utilisation of oligosaccharides and polysaccharides has attracted the greatest attention among biotic elicitors. Many non-graminous species have been studied to see how chitosan affects bean (Mendoza-Sánchez et al., 2016), soybean (Khan et al., 2003), lentil broccoli (Barrientos Carvacho et al., 2014) and lettuce (Viacava et al., 2015). Utilization of elicitors for sprouting is still an evolving area, however, there are limited studies that objectify the systematic role of elicitors, and still strong evidences are required to understand their mode of action and mechanism and utilization. ...
Pulses are among one of the cheapest and nutritious source having abundance of proteins and other essential nutrients for vegetarian especially in the developing countries. However, pulses like kidney bean and lentil also contains significant amount of anti-nutritional factors which are eliminated by simple processes like sprouting. Compared with raw pulses, sprouts are usually consumed after sprouting and are minimally processed to have improved nutrient profile and therefore have extensive consumer acceptance. During sprouting, functional bioactive compounds are increased to appreciable levels which lower the risk of many fatal disorders i.e. cardiovascular diseases (CVD), diabetes, inflammation, high blood pressure and cancer. The benefits of sprouting can be further promoted by the application of pre-treatments such as osmopriming, hydropriming and thermopriming. The functional composition of sprouts depends on the method of germination, presence of elicitors, seed weight and solution ratio, soaking time, temperature and light which thereby plays a critical role in their digestibility. Novel technologies including high pressure processing, radiation and ultrasonication improve accessibility of enzymes and reduce anti nutritional factors without altering nutritional profile and storage in low temperature are essential criteria for the acceptability of sprouts. The chapter aims to provide updated information on the scientific and technological interventions to improve and maintain the quality of the sprouted lentils and kidney beans to the highest level possible.
... The application of CHT increased the expression and the activity of different enzymes involved in the biosynthesis of phenolic compounds in pear [51], citrus [52], and Scrophularia striata [53]. Additionally, the activity of the phenylalanine ammonia-lyase, the first key enzyme of the phenylpropanoid pathway in plants, was found to be elicited by CHT in soybean [54], rice [55], and apple [56]. This mechanism should be confirmed in hemp inflorescences by future studies. ...
In the present study, the phytochemical content and the antioxidant activity in the inflorescences of the monoecious hemp cultivar Codimono grown in southern Italy were assessed, and their elicitation was induced by foliar spray application of 50 mg/L and 250 mg/L of chitosan (CHT) at three different molecular weights (low, CHT L; medium, CHT M; high CHT H). The analysis of the phytochemical profile confirmed that cannabinoids were the most abundant class (54.2%), followed by flavonoids (40.3%), tocopherols (2.2%), phenolic acids (1.9%), and carotenoids (1.4%). Cannabinoids were represented almost exclusively by cannabidiol, whereas cannabigerol and Δ9-tetrahydrocannabinol were detected at very low levels (the latter was below the legal limit of 0.3%). The most abundant flavonoids were orientin and vitexin, whereas tocopherols were mainly represented by α-tocopherol. The antioxidant activity was found to be positively correlated with flavonoids and tocopherols. Statistical analysis revealed that the CHT treatments significantly affected the phytochemical content and the antioxidant activity of hemp inflorescences. Notably, a significant increase in the total phenolic content (from +36% to +69%), the α-tocopherol (from +45% to +75%) and β+γ-tocopherol (from +35% to +82%) contents, and the ABTS radical scavenging activity (from +12% to +28%) was induced by all the CHT treatments. In addition, treatments with CHT 50 solutions induced an increase in the total flavonoid content (from +12% to +27%), as well as in the vitexin (from +17% to +20%) and orientin (from +20% to +30%) contents. Treatment with CHT 50 L almost always resulted in the greatest increases. Overall, our findings indicated that CHT could be used as a low-cost and environmentally safe elicitor to improve the health benefits and the economic value of hemp inflorescences, thus promoting their employment in the food, pharmaceutical, nutraceutical, and cosmetic supply chains.
... 28 For instance, the application of chitin initiates a wide spectrum of plant defense mechanisms. These encompass the production, release, and/or activation of various plant defenses, including anti-toxins, 29 phenols, 30 terpenes, 31 and reactive oxygen species. 32 Chitin serves as a physical barrier, effectively hindering the penetration and spread of pathogens on plant surfaces. ...
BACKGROUND
In recent years, nanomaterials‐based pesticide carriers have garnered significant attention and sparked extensive research. However, most studies have primarily focused on investigating the impact of physical properties of nanomaterials, such as size and modifiable sites, on drug delivery efficiency of nano‐pesticides. The limited exploration of biologically active nanomaterials poses a significant obstacle to the advancement and widespread adoption of nano‐pesticides. In this study, we prepared chitin nanocrystals (ChNC) based on acid hydrolysis and systematically investigated the differences between nano‐ and normal chitin against plant bacteria (Pseudomonas syringae pv. tabaci). The primary objective was to seek out nanocarriers with heightened biological activity for the synthesis of nano‐pesticides.
RESULTS
Zeta potential analysis, Fourier Transform infrared spectrometry (FTIR), X‐Ray diffraction (XRD), Atomic force microscopy (AFM) and Transmission electron microscopy (TEM) identified the successful synthesis of ChNC. ChNC showcased remarkable bactericidal activity at comparable concentrations, surpassing that of chitin, particularly in its ability to inhibit bacterial biofilm formation. Furthermore, ChNC displayed heightened effectiveness in disrupting bacterial cell membranes, resulting in the leakage of bacterial cell contents, structural DNA damage, and impairment of DNA replication. Lastly, potting experiments revealed that ChNC is notably more effective in inhibiting the spread and propagation of bacteria on plant leaves.
CONCLUSION
ChNC exhibited higher antibacterial activity compared to chitin, enabling efficient control of plant bacterial diseases through enhanced interaction with bacteria. These findings offer compelling evidence of ChNC's superior bacterial inhibition capabilities, underscoring its potential as a promising nanocarrier for nano‐pesticide research. © 2023 Society of Chemical Industry.
... Its primary use in agriculture is as a natural seed treatment and plant growth enhancer, as well as a biopesticide that improves the ability of plants to defend against fungal infections in an ecologically friendly way. 77 Khan et al. 78 showed that plants with high chitin content have better disease resistance. CH is non-toxic and has a high affinity, with F I G U R E 1 1 Effect of chitosan powder and polystyrene on plant height of maize. ...
The widespread usage and production of microplastics (MPs) products has resulted in a surge of plastic waste in the natural environment. Chitosan (CH) is a natural polymer derived from chitin, found in the shells of crustaceans such as shrimp and crabs and studied extensively for its potential use as an amendment. The dynamic interplay between plastic, specifically polystyrene (PS), and the potential of CH as a soil enhancer holds pivotal implications for soil health and crop vitality. While PS seems to wield minimal influence on soil pH, CH demonstrates a distinct ability to lower pH levels significantly. However, the synergy between CH and PS in altering soil pH is relatively limited. Importantly, CH emerges as a compelling countermeasure against the detrimental impact of PS on soil chemistry. Its application brings about promising changes, such as mitigating nutrient depletion and enhancing organic matter (OM). Shifting focus to crop growth, PS emerges as a growth inhibitor, substantially reducing maize biomass and chlorophyll content. Conversely, CH emerges as a growth stimulant, positively affecting root and shoot dry weights, leaf area, and plant height. The interplay between CH and PS manifests complex outcomes on these growth metrics, indicating interdependence. These findings resonate with sustainable soil management practices and the optimization of crop productivity. Further scrutiny is warranted to unravel the underlying mechanisms and long-term consequences, offering a comprehensive understanding of the interaction between PS, CH, and the ecological landscape. Such insights pave the way for informed decisions in ecological preservation and agricultural sustenance.
... and PAL (EC 4.3.1.5) enzymatic activity were measured using a modified procedure based on Khan et al. [37]. Mango fruit tissue (1 g) was homogenized with an ice-cold Tris-HCl buffer (50 mM, pH 8.5) containing 5% (w/v) polyvinylpolypyrrolidone (PVPP) and 14.4 mM β-mercaptoethanol to obtain a preliminary extract. ...
Background
The aim of this study was to compare and investigate the effects of 1-(3-phenyl-propyl) cyclopropene (PPCP) and melatonin (MT) as anti-ethylene agents on postharvest senescence, quality, chilling tolerance, and antioxidant metabolism in the mango fruit cv. “Keitt”. The study involved exposing the fruit to 20 μL L− 1 PPCP or 200 μM MT, in addition to a control group of untreated fruit, before storing them at 5 ± 1 °C for 28 d. The findings revealed that the treatments with PPCP and MT were effective in reducing chilling injury and preserving fruit quality when compared to the control group.
Results
The use of 20 μL L− 1 PPCP was an effective treatment in terms of mitigating chilling injury and preserving fruit quality for 28 d. This was attributed to the decrease in metabolic activity, specifically the respiration rate and the production of ethylene, which led to the maintenance of fruit firmness and bioactive compounds, energy metabolism, and antioxidant activity, such as ascorbic acid, total flavonoids, trolox equivalent antioxidant capacity, dehydroascorbate reductase, glutathione reductase activity, ATP, and ATPase activity. The study also found that the MT treatment at 200 μM was effective in reducing chilling injury and weight loss and improving membrane stability. Additionally, it led to a decrease in malondialdehyde content and electrolyte leakage, and the maintenance of fruit quality in terms of firmness, peel and pulp colour values for mango peel and pulp total carotenoid content, as well as phenylalanine ammonia lyase and tyrosine ammonia lyase activity. These findings indicate that PPCP and MT have the potential to be efficient treatments in maintaining mango quality and minimizing post-harvest losses.
Conclusion
The utilisation of treatments with 20 μL L− 1 of PPCP or 200 μM MT was found to effectively preserve the postharvest quality parameters, in terms of bioactive compounds, energy metabolism, and antioxidant activity, of mangoes cv. “Keitt” that were stored at 5 ± 1 °C for 28 d.
... Based on these findings, the contribution of PAL and TAL may depend on plant species and the type of stress applied (abiotic or biotic stress). Some investigations have proposed that this differential role can be explained by the association between PAL activity and enzymes from dicots and monocots, while TAL activity is more prevalent in monocots [95]. PAL and TAL are key enzymes in the phenylpropanoid pathway. ...
Plants are highly sensitive to various environmental stresses, which can hinder their growth and reduce yields. In this study, we investigated the potential of seed priming with salicylic acid (SA), gibberellic acid (GA3), and sodium chloride (NaCl) to mitigate the adverse effects of salinity stress in Hordeum vulgare at the germination and early seedling stages. Exposing H. vulgare seeds to salt stress reduced the final germination percentage and seedling shoot and root growth. Interestingly, all seed treatments significantly improved salt-induced responses, with GA3 being more effective in terms of germination performance, plant growth, and photosynthesis. SA priming exhibited promising effects on antioxidant defense mechanisms, proline, sugar, and ascorbic acid production. Notably, SA priming also suppressed reactive oxygen species accumulation and prevented lipid peroxidation. These findings highlight the ability of SA to manage crosstalk within the seed, coordinating many regulatory processes to support plant adaptation to salinity stress.
... Taken together, our results point to a rapid and significant activation of pea genes involved in regulation of host defense responses, induced by CO8-DA, in accordance with previous findings for chitin-related compounds in Arabidopsis, rice, potato, tea (Chen et al., 2020;Lemke et al., 2020;Siriwong et al., 2021;Ichimaru et al., 2022;Ou et al., 2022). We have shown that a set of genes encoding specific enzymes involved in the biosynthesis of phytoalexins and other secondary metabolites was up-regulated in response to CO8-DA, that was in line with previous findings in other plants (Vasyukova et al., 2001;Khan et al., 2003;Zhang et al., 2020). The pea plant treatment with CO8-DA stimulated the synthesis of such components as lignins, reinforcing the cell wall. ...
Since chitooligosaccharides (COs) are water-soluble, biodegradable and nontoxic compounds, their application may be considered as a promising plant-protecting agent. However, the molecular and cellular modes of action of COs are not yet understood. In this study, transcriptional changes in pea roots treated with COs were investigated via RNA sequencing. Pea roots treated with the deacetylated CO8-DA at low concentration (10⁻⁵ М) were harvested 24 h after treatment and their expression profiles were compared against medium-treated control plants. We observed 886 differentially expressed genes (fold change ≥ 1; p-value < 0.05) 24 h after treatment with CO8-DA. Gene Ontology term over-representation analysis allowed us to identify the molecular functions of the genes activated in response to CO8-DA treatment and their relation to biological processes. Our findings suggest that calcium signaling regulators and MAPK cascade play a key role in pea plant responses to treatment. Here we found two MAPKKKs, the PsMAPKKK5 and PsMAPKKK20, which might function redundantly in the CO8-DA-activated signaling pathway. In accordance with this suggestion, we showed that PsMAPKKK knockdown decreases resistance to pathogenic Fusarium culmorum fungi. Therefore, analysis showed that typical regulators of intracellular signal transduction pathways involved in triggering of plant responses via CERK1 receptors to chitin/COs in Arabidopsis and rice may also be recruited in legume pea plants.
... In most works, the effect of chitosan on PAL was determined within a few hours or days after treatment. Numerous studies indicated an increase in PAL activity and upregulation of PAL gene expression under the action of chitosan in different crops and treatment techniques [20,[56][57][58][59][60]. However, few studies examined the effects of chitosan over a longer period of time after treatment. ...
Citation: Lyalina, T.; Shagdarova, B.; Zhuikova, Y.; Il'ina, A.; Lunkov, A.; Varlamov, V. Effect of Seed Priming with Chitosan Hydrolysate on Lettuce (Lactuca sativa) Growth Parameters. Molecules 2023, 28, 1915. Abstract: Seed priming increases germination, yield, and resistance to abiotic factors and phytopathogens. Chitosan is considered an ecofriendly growth stimulant and crop protection agent. Chitosan hydrolysate (CH) is an unfractionated product of hydrolysis of high-molecular-weight crab shell chitosan with a molecular weight of 1040 kDa and a degree of deacetylation of 85% with nitric acid. The average molecular weight of the main fraction in CH was 39 kDa. Lettuce seeds were soaked in 0.01-1 mg/mL CH for 6 h before sowing. The effects of CH on seed germination, plant morphology, and biochemical indicators at different growth stages were evaluated. Under the 0.1 mg/mL CH treatment, earlier seed germination was detected compared to the control. Increased root branching was observed, along with 100% and 67% increases in fresh weight (FW) at the 24th and 38th days after sowing (DAS), respectively. An increase in the shoot FW was found in CH-treated plants (33% and 4% at the 24th and 38th DAS, respectively). Significant increases in chlorophyll and carotenoid content compared to the control were observed at the 10th DAS. There were no significant differences in the activity of phenylalanine ammonia-lyase, polyphenol oxidase, β-1,3-glucanase, and chitinase at the 24th and 38th DAS. Seed priming with CH could increase the yield and uniformity of plants within the group. This effect is important for commercial vegetable production.
... This is also confirmed by the results of an experiment carried out on Scrophularia striata by Beshamgan et al. [66], which showed a two-fold higher increase in PAL activity compared to TAL due to cadmium accumulation. A higher contribution of PAL in relation to TAL in flavonoid biosynthesis was also found by Feduraev et al. [60] in studies on wheat seedlings and by Khan et al. [67] after the application of the elicitors chitin and chitosan to soybean leaf tissues. This can be explained by the different functions of PAL and TAL, which can be differently regulated by specific lignin pathway intermediates, and via organized multienzyme complexes [68]. ...
Heavy metal stress can lead to many adverse effects that inhibit cellular processes at various levels of metabolism, causing a decrease in plant productivity. In response to environmental stressors, phenolic compounds fulfill significant molecular and biochemical functions in plants. Increasing the biosynthesis of phenolic compounds in plants subjected to heavy metal stress helps protect plants from oxidative stress. A pot experiment was carried out to determine the effect of the accumulation of copper (Cu) and lead (Pb) salts at concentrations of 200, 500, and 1000 ppm on seed germination, the activity of enzymes in the phenylalanine ammonia-lyase pathway (PAL) and tyrosine ammonia-lyase (TAL), along with the total phenol and flavonoid contents in seedlings of hybrid Triticum aestivum L. (winter wheat) cultivars. The accumulation of heavy metals, especially Cu, had a negative impact on the seed germination process. The cultivar “Hyacinth” reacted most strongly to heavy metal stress, which was confirmed by obtaining the lowest values of the germination parameters. Heavy metal stress caused an increase in the activity of PAL and TAL enzymes and an increase in the accumulation of phenolic compounds. Under the influence of Cu, the highest activity was shown in cv. “Hyvento” (especially at 200 ppm) and, due to the accumulation of Pb, in cv. “Hyacinth” (1000 ppm) and cv. “Hyking” (200 ppm). The cultivar “Hyking” had the highest content of phenolic compounds, which did not increase with the application of higher concentrations of metals. In other cultivars, the highest content of total phenols and flavonoids was usually observed at the lowest concentration (200 ppm) of the tested heavy metals, Cu and Pb.
... HY5 is also known to activate the expression of MYB12 and MYB111 [39] , which are involved in the regulation of flavonol synthase [40] . Moreover, HY5 can respond to ABA by specifically binding to ABI5 chromatin [41] . In this research, unigene0087548, annotated as an HY5-like gene, and unigene0005403, annotated as an MYB12 homolog, were both significantly upregulated in ABA-treated pansy petals (Fig. 7), suggesting that HY5 may have responded to ABA treatment and interacted synergistically with VwMYB12 to promote anthocyanin biosynthesis in pansy. ...
Viola × wittrockiana (pansy) is an important ornamental plant, particularly during winter and spring. In previous studies, we found that the tyrosine decarboxylase gene of pansy (VwTYDC) was expressed differently in blotched and non-blotched areas of pansy petals, suggesting that tyrosine may have a role in anthocyanin biosynthesis. In this study, we found that virus-induced gene silencing of VwTYDC caused an accumulation of pink pigmentation in pansy petals. Likewise, exogenous tyrosine treatment (TYRT) induced the formation of black stripes in non-blotched petal areas. Metabolome analysis indicated that the contents of two anthocyanins, cyanidin-3-O-glucoside and cyanidin-3-O-rutinoside, increased significantly in the TYRT areas. RT-qPCR results revealed that the anthocyanin-related genes VwHCT, VwC3′H, VwCHS, and VwUGT were upregulated in the same areas. Transcriptome analysis revealed that four genes involved in the abscisic acid (ABA) biosynthesis pathway (VwNCED, VwABA2, VwAAO3, and VwCYP707A) were significantly upregulated in the same TYRT areas. ABA content was measured by ESI-HPLC-MS/MS, and ABA content was significantly higher in TYRT areas than in control areas. In addition, when exogenous ABA was spread onto non-blotched petal areas, anthocyanin biosynthesis genes were upregulated just as with tyrosine. Thus, transcriptome and metabolite analyses revealed a possible novel regulatory network for anthocyanin biosynthesis in which tyrosine induces ABA synthesis and ABA then promotes anthocyanin biosynthesis in pansy petals.
... Phenylalanine ammonia-lyase transforms L-phenylalanine to ammonia and trans-cinnamic acid [124]. It is induced in host tissues as a result of pathogen infection [69]. In grape berries, rice, and wheat, elicitation with chitosan resulted in an increase in phenylalanine ammonia-lyase [37]. ...
In the spirit of returning to nature and using scientific applications to raise plant efficiency and reduce pathogen risk, scientists began searching for safe, natural alternatives to pesticides that are highly effective and low cost. On top of these alternatives, chitosan came with its biodegradability, biocompatibility, antimicrobial activity, and nontoxicity, which granted it dual energetic effects during the host-pathogen interaction. Chitosan promotes plant growth, regulates plant cell homeo-stasis and metabolic processes, and triggers plant defense mechanisms; on the other hand, it inhibits the ability of pathogens by disrupting pathogen growth and reducing reproduction, wherefore chitosan will become an increasingly prevalent and ideal resource for agricultural sustainability.
... PAL activity was done by the method of [27]. One millilitre of reaction mixture containing 500 μl of Tris-HCl buffer (pH 8), 100 μl enzyme extract and 6 μmol L-Phenylalanine incubated for 60 min at 40 • C and the reaction was stopped by adding 50 μl 5 N HCl. ...
Wilt disease, caused by Fusarium oxysporum. f. sp. lycopersici, is a global threat to tomato production that needs to be addressed seriously. The current research envisages the use of two self-compatible Bacillus strains, Bacillus tequilensis PKDN31 and Bacillus licheniformis PKDL10, in a combinatorial approach. The spent supernatant of liquid cultures from strains PKDN31 and PKDL10 showed in vitro antifungal activity against Fusarium sp. attaining an inhibition percentage of 95.33% and 96.54%, respectively. The bacterial isolates lytic activity against Fusarium oxysporum was evaluated by scanning electron microscopic analysis and lytic enzyme production of amylase, lipase, protease and β-1,3 glucanase. Furthermore, PKDN31 and PKDL10 produced siderophores and had root colonizing ability that enhanced the biocontrol efficiency. Combined in vivo inoculation of Bacillus tequilensis PKDN31 and Bacillus licheniformis PKDL10 on tomato seeds revealed that the strains could induce systemic resistance in tomato against Fusarium oxysporum. f. sp. lycopersici by increasing defence enzymes such as β-1,3 glucanase, polyphenol oxidase, peroxidase, phenylalanine ammonia-lyase, chitinase, and total phenol accumulations. Pot culture experiments also proved the biocontrol efficacy of the above dual culture supplementation as this treatment displayed a better growth as well as defense against Fusarium challenge compared to the controls. The obtained results suggest that rhizobacterial isolates could be employed as systemic resistance inducers and biocontrol agents in tomato plants to protect against Fusarium wilt disease.
... Considering the serious consequences that pesticides may have on human health (male infertility, cancers, negative effects on fetuses, etc.), chitin and chitosan seem to be well-known and eco-friendly biocontrol agents due to their biodegradable, nontoxic, and biocompatible properties (Hassan & Chang, 2017). They act by increasing the synthesis of secondary metabolites that enhance plant immunological defenses (phenylalanine ammonia lyase (PAL) and tyrosine ammonia lyase (TAL)) (Khan et al., 2003). Recently, some studies have found that chitin and its derivatives have strong antibacterial activities in vitro and in vivo against a variety of plant pathogenic bacteria like Ralstonia solanacearum (Farag et al., 2017) and Xanthomonas spp. ...
Ralstonia solanacearum is one of the most destructive pathogens of vegetables causing very important economic losses. In 2019, 20 strains of R. solanacearum were collected from potato tubers in Morocco. After their identification, the inhibitory effect of colloidal solutions of chitin and/or chitosan was evaluated in vitro on a solid medium (Mueller Hinton) supplemented with these biopolymers. The concentrations (25, 50, or 100 mg L-1) contributed to significant inhibition of the growth of the isolated strains that led to an inhibition of 45.04% with the combination of chitin-chitosan (100 mg L-1), 58.92% with the addition of 100 mg L-1 of chitin, and 68.74% in the presence of chitosan at 25 mg L-1. Likewise, in experiments with Solanum lycopersicum L. seedlings, chitin derivatives significantly promoted stem and root growth. Stem length increased by 54.95% when chitin was added at 25 mg L-1, while soil amendment with 100 mg L-1 of chitosan increased root length by 82.55% compared to the control. The severity of bacterial wilt due to R. solanacearum was reduced by 117.02% when we added 100 mg L-1 of chitosan to the soil. However, the severity of this disease decreased by 142.86% when the soil was amended with chitin at 50 mg L-1. These findings are consistent with prior research that suggests using this technique to manage bacterial wilt caused by R. solanacearum.
... In particular, chitosan coatings applied to carrot slices significantly increased TPC and antioxidant activity of the samples, probably because of three reasons. Firstly, the demonstrated elicitor activity of chitosan and its stimulant action of plant's secondary metabolism may have induced the biosynthesis of phytochemical compounds with antioxidant activity such as polyphenols (Khan et al., 2003;Simões et al., 2009). Secondly, the gas barrier properties of chitosan, that reduces the tissue oxygen intake, could have reduced the activity of polyphenol oxidase (PPO) enzyme and limited polyphenol degradation, as indicated by several authors (Pasquariello et al., 2015;Wang & Gao, 2013). ...
The present study evaluated the effectiveness of the application of active edible coatings based on chitosan containing free thyme essential oil (TO) and microencapsulated TO in β-cyclodextrin (β-CD) in enhancing the quality and shelf-life of sliced carrots during 13 days of refrigerated storage. All coated samples showed less superficial discoloration and better organoleptic quality than non-coated samples. In fact, non-coated carrot slices showed overall visual quality (OVQ) scores below the limit of acceptance from day 9 of storage, while all the other samples exhibited acceptable values of OVQ during the entire sampling period. Higher values of total phenolics content (TPC) and antioxidant capacity were observed in coated samples with respect to uncoated ones. Moreover, coatings containing TO were more effective in enhancing the phytochemical quality of the samples, and those containing the essential oil microencapsulated in β-CD presented the highest values of TPC and antioxidant activity along storage. An initial reduction in the counts of mesophilic, psychrophilic, and yeast and molds populations was detected in the samples coated with free TO with respect to the other samples, effect that was not maintained during storage. On the contrary, the use of microencapsulated TO in the chitosan coatings allowed to reduce the microbial counts from day 6 till the end of storage. Results demonstrate the potential of applying chitosan coatings enriched with thyme essential oils to improve the quality of minimally processed carrots during storage. In addition, the efficacy of β-CD as a carrier of thyme essential oil bioactives is also highlighted.
... and tyrosine ammonia lyase (TAL, EC 4.3.1.25) were assayed, according to the protocol reported by Khan et al. [34], with some modifications. An extract was initially performed, where 1 g of mango fruit tissue (peel or pulp) was homogenised in ice-cooled Tris-HCl buffer (50 mM, pH 8.5) containing 5% (w/v) polyvinylpolypyrrolidone (PVPP) and 14.4 mM β-mercaptoethanol. ...
Melatonin (MT) treatment (100 µM, 2 h) was applied to four mango fruit cultivars (‘Langra’, ‘Chaunsa’, ‘Dashehari’, and ‘Gulab Jamun’), before being stored at 5 ± 1 °C for 28 d, in order to alleviate chilling injury (CI). Maximum CI reduction was observed in ‘Langra’ mangoes, and minimum in ‘Gulab Jamun’ mangoes. This positive effect on quality preservation was associated with an increased concentration of endogenous MT, which prevented the accumulation of reactive oxygen species (H2O2 and O2.−) and stimulated non-enzymatic antioxidants (total phenolic compounds and total flavonoids), possibly due to higher activity of phenylalanine ammonia lyase and tyrosine ammonia lyase. Increased antioxidant activity was also documented in MT-treated ‘Langra’ mangoes, according to four different assays (DPPH, TEAC, FRAP, and CUPRAC) and higher activity of six antioxidant enzymes (superoxide dismutase, catalase, peroxidase, ascorbate peroxidase, glutathione reductase, and dehydroascorbate reductase). In contrast, ‘Gulab Jamun’ mangoes showed minimal or no positive effects on the aforementioned variables in response to the exogenous MT application. ‘Chaunsa’ and ‘Dashehari’ mangoes had some intermediate effects on their antioxidant system (enzymatic and non-enzymatic) and alleviation of CI, when treated with exogenous MT. We conclude that exogenous MT exerts a cultivar-dependent stimulating effect on the antioxidant system of mangoes, which results in an increase in the fruits’ resistance to low temperature.
... POD and PPO activities increase in various sorghum cultivars under aphid stress, according to Chang and coworkers (2008). In addition, the enzyme tyrosine ammonia-lyase (TAL) is activated (Khan et al., 2003). The activities of TAL and PAL are connected to the concentrations of cellulose, hemicellulose, and lignin, which may help enhance the structural barrier. ...
Aphids are harmful agricultural insect pests that feed on the phloem sap of their hosts, infecting them with diseases. Plant-aphid interaction is a dynamic system that is always changing and varying. During their life cycle, several aphid species change their host plant. They travel between main and secondary host plant species in the spring and fall. This host shift has happened due to the phloem sap's nutritional importance and necessity for reproduction. According to certain experiments, the aphid parasitism impact reduces the number of inflorescences and the average weight of floral buds. With the aid of enzymatic adaptability and sequestering secondary metabolites, the host plant possesses biochemical and physical defence mechanisms. Aphids circumvent this by secreting Mixed Function Oxidase (MFO), which catalyses oxidative reactions, allowing them to eat, develop, and breed on their host plant.
... TAL activity was determined by the method of Khan et al., (2003) with slight modifications. To 0.5 ml of 0.05 M tyrosine in 0.1 M tris HCl (pH 9.5), 0.4 ml 50 mM potassium phosphate buffer (pH 8.8) and 0.1 ml of enzyme source were added. ...
Host plant resistance is an important component of pest management, and information on contribution of different mechanisms of resistance is important for developing cultivars with resistance to the target pests. Therefore, induced resistance was studied in five sorghum genotypes against Chilo partellus by using infested and non-infested plants under greenhouse conditions. The activity of plant defensive enzymes and the secondary metabolites were recorded at 7 days after infestation and their induction varied among the genotypes and treatments. The resistant sorghum genotypes ICSV 700, IS 2205 and ICSV 93046 suffered lower leaf damage by the neonate larvae of C. partellus (damage rating (DR) 2.8–3.7) as compared to the susceptible checks, ICSV 1 and Swarna (DR 6.4 and 7.0, respectively). ICSV 700, IS 2205 and ICSV 93046 exhibited greater enzymatic activity [peroxidase (POD), polyphenol oxidase (PPO), phenylalanine ammonia lyase (PAL) and tyrosine ammonia lyase (TAL)] and had more amounts of phenols than the susceptible check, Swarna. This information will be useful for developing sorghum genotypes with resistance to C. partellus for sustainable crop production.
Supplemental data for this article is available online at https://doi.org/10.1080/09670874.2022.2036863 .
... Also, treatment with chitosan in ball pepper (Capsicum annuum L.) is reported to increase chitinase and glucanase activities in both seed and seedling [120]. Upregulation of genes for phenolic biosynthesis after chitosan treatment has been reported previously [135,136]. In addition, enhanced level of carbon and nitrogen metabolism was found in wheat treated with chitosan [137]. ...
Chitosan is a naturally occurring biological macromolecule and second most abundant polysaccharide next to cellulose, derived from deacetylation of chitin. Due to its biocompatibility, biodegradability, nontoxic and broad spectrum of antimicrobial activity, it has become an important field of drug delivery system study. With the advancement in nanotechnology, chitosan based nanoformulations have sought considerable attention in agricultural sciences. The first part of this review focuses on the overview of chitosan and its nanoparticles, its different mode of synthesis and challenges, and controlled release mechanism of encapsulated molecules. The subsequent section focuses on the uptake and translocation of chitosan based nanoformulation including plant growth, nutrition and special focus on abiotic stress mitigation strategies. We conclude that chitosan based nanoformulation holds great promises in encapsulating bioactive molecules for controlled release thus reduces environmental hazard, and improves plant growth, yield and subsequently mitigates various biotic and abiotic stresses. Chitosan based nanoformulations have good controlled release behaviour and long stability of bioactive compounds encapsulated inside chitosan nanoparticle, and have prosperous future for improving agricultural productivity in the era of climate change.
... PAL is the first enzyme in the public phenylalanine biosynthesis pathway. In many plants, PAL is encoded by polygene family members and plays different roles in phenylpropane metabolism [39,40]. PAL1 and PAL2 were proven to be related to the synthesis of lignin and flavonoids in Arabidopsis thaliana, so the activity of PAL is a key factor in the synthesis of many phenolic compounds and lignin [41,42]. ...
Seashore paspalum is a major warm-season turfgrass requiring frequent mowing. The use of dwarf cultivars with slow growth is a promising method to decrease mowing frequency. The present study was conducted to provide an in-depth understanding of the molecular mechanism of T51 dwarfing in the phenylpropane pathway and to screen the key genes related to dwarfing. For this purpose, we obtained transcriptomic information based on RNA-Seq and proteomic information based on iTRAQ for the dwarf mutant T51 of seashore paspalum. The combined results of transcriptomic and proteomic analysis were used to identify the differential expression pattern of genes at the translational and transcriptional levels. A total of 8311 DEGs were detected at the transcription level, of which 2540 were upregulated and 5771 were downregulated. Based on the transcripts, 2910 proteins were identified using iTRAQ, of which 392 (155 upregulated and 237 downregulated) were DEPs. The phenylpropane pathway was found to be significantly enriched at both the transcriptional and translational levels. Combined with the decrease in lignin content and the increase in flavonoid content in T51, we found that the dwarf phenotype of T51 is closely related to the abnormal synthesis of lignin and flavonoids in the phenylpropane pathway. CCR and HCT may be the key genes for T51 dwarf. This study provides the basis for further study on the dwarfing mechanism of seashore paspalum. The screening of key genes lays a foundation for further studies on the molecular mechanism of seashore paspalum dwarfing.
... Another reason for the stimulating effects of WMB on polyphenol content may be the presence of previously mentioned chitin and its derivatives from fungal cell walls. These compounds seem to exert strong biological influence on plants by improving their immune system and the activity of antioxidant enzymes (Khan et al., 2003;Zhang et al., 2012aZhang et al., , 2012b. GAE A comparison of the content of total polyphenols and antioxidant activity in plant organs revealed on average six times greater concentration of total polyphenols in the petals of both T. patula cultivars than in the leaves. ...
Champignon stalks are organic waste material widely underrated as a source of nutrients and substances with bio-stimulatory properties. French marigold (Tagetes patula L., Asteraceae) is an important crop plant that can be used in variety of different industries. This study assessed the usefulness of waste mushroom biomass - WMB (obtained in the production of champignon Agaricus bisporus), in the pot cultivation of two T. patula cultivars (‘Mikrus’ and ‘Petite Yellow’). It examined growth, plant biomass, photosynthetic pigments content, leaves and petals color and their antioxidant potential as well as the essential oil content and composition of plants grown in 100 % peat (control) and peat supplemented with WMB (5 % by volume). Postharvest physicochemical properties and nutrient status of the media were also investigated. The addition of WMB enriched the medium in nitrogen, potassium and sulfur (by 14−28 %, 106−160 % and 33−100 %, respectively), and reduced its C:N ratio without affecting its electrical conductivity and pH. The plants growing in peat supplemented with WMB had greater fresh weight (by 32−54 %) and number of flowers (by 35−46 %), higher total chlorophyll content in the leaves (by 73−117 %) and more intense color of leaves and petals than those growing in peat alone. Moreover, the leaves and petals had greater content of total polyphenols and higher antioxidant activity (determined by DPPH, ABTS and FRAP). The results of gas chromatography-mass spectrometry (GC–MS) analysis of essential oils revealed that the oils of leaves contained higher amounts of spathulenol (2.3−2.9 %), isopropyl myristate (2.6−13.3 %) and palmitic acid (20.7 %−22.7 %). Whereas, the oils of the petals showed higher concentration of caryophyllene (1.5−4.6 %), myristic acid (11.0−19.1 %) and 2,2′:5′2″-terthiophene (7.7−12.8 %). Interestingly, dodecanoic acid (2.7−3.8 %) was found only in the oils obtained from T. patula petals. Moreover, the slightly higher content of this compound was found in the plants growing in peat supplemented with WMB (3.8 % and 2.9 % for ‘Mikrus’ and ‘Petite Yellow’ cultivars, respectively). In conclusion, the present study suggests a new, environmental-friendly strategy to increase plant productivity and bioactive compounds content by using champignon stalks as a medium supplement.
... The chitin is used in the agricultural sector as an elicitor for the plants. The chitinous products decomposition releases the nitrogen, contributing to soil and plant enrichment [25]. ...
... The increased amounts of total phenolic and flavonoid contents in chitosan-coated samples may be elucidated by the ability of chitosan to stimulate the activities of phenylalanine ammonia-lyase and tyrosine ammonia-lyase, which participate in the biosynthesis of these compounds (Khan, Prithiviraj, & Smith, 2003). Moreover, Katiyar, Hemantaranjan, and Singh (2015) explained the improving of free radical scavenging activity of chitosan coat by inducing antioxidant enzyme activities such as superoxide dismutase, catalase and peroxidase. ...
Smoked herring is a very popular traditional fish product widely consumed in Egypt. Nonetheless, rapid mold growth and lipid oxidation, with consequent short shelf-life and loss of the essential characteristics, including the smoking color and flavor, are emerged as adverse problems during storage of this product. This study was aimed to improve the quality and lipid stability of smoked herring using chitosan coating. To achieve this goal, smoked herrings were collected from local producers and divided into 5 groups, including two controls (water-dipped and 0.5% lactic acid-dipped samples) and three treated groups (2%, 3% and 4% chitosan-coated samples) followed by storage at -18 °C for 3 months during which microbiological, physicochemical, and sensorial analyses, besides determination of phenolics, flavonoids, and the antioxident activity were carried out. The results revealed that chitosan-coated (3% and 4%) samples exhibited more than 4 log10 CFU/g reduction in aerobic plate count, along with complete suppression of psychrotrophic, Enterobacteriaceae, yeast and mould counts, which were all under the detectable levels (2 log10 CFU/g). Chitosan improved and maintained the phenolic and flavonoid compounds along with the free radical scavenging activity in chitosan-coated smoked fish during frozen-storage. Moreover, chitosan coating induced significant improvement of the physiochemical quality including; pH, total volatile base nitrogen, trimethylamine, thiobarbituric acid values, free fatty acid %, acid number, together with the sensory attributes, compared to control uncoated ones. The study concluded that chitosan coating can be a good choice for fish industry to overcome the problems that arise in smoked fish.
... They entail the promoting of the production of secondary metabolites that fortifies the plants immune defense mechanisms. Chitin derivatives, for example, stimulate the production of phenylalanine ammonia-lyase (PAL) and tyrosine ammonia-lyase (TAL) that are considered to be the two central enzymes in the phenylpropanoid pathway, which itself intervenes in the responses to the biotic and abiotic factors [52]. Another analysis executed by Dörnenburg and Knorr in 1994 [53], once more attests that chitosan and chitin induce the biosynthesis of anthraquinone (a compound of the family of polycyclic aromatic hydrocarbons) that plays an important role in the protection procedure of plants. ...
Background
During active infections, plants prevent further spread of pathogenic microorganisms by inducing the rapid programmed death of cells around the infection point. This phenomenon is called the hypersensitive response and is a common feature of plant immune responses. Plants recognize conserved structures of pathogenic microorganisms, called pathogen-associated molecular patterns (PAMPs), e.g ., flagellin 22 (flg22) and chitohexose, which bind to receptors on plant cells to induce various immune-response pathways. Although abiotic stresses are known to alter photosynthesis, the different effects of flg22 and chitohexose, which are involved into PAMP-induced signaling, on photosynthesis needs further study.
Methods
In the present study, we assessed the role of PAMPs in peanut ( Arachis hypogaea ) photosynthesis, particularly, the interaction between PAMPs and Ca ²⁺ signal transduction pathway.
Results
Both flg22 and chitohexose significantly promoted the expression of the pathogenesis-related genes PR-4 and PR-10 , as did Ca ²⁺ . We found that Ca ²⁺ is involved in downregulating the photosystem II (PSII) reaction center activity induced by the flg22 immune response, but the role of chitohexose is not obvious. Additionally, Ca ²⁺ significantly reduced the non-photochemical energy dissipation in the flg22- and chitohexose-induced immune response.
Conclusion
These results indicated that flg22 and chitohexose can trigger peanut immune pathways through the Ca ²⁺ signaling pathway, but they differ in their regulation of the activity of the PSII reaction center.
Copper (Cu) pollution is one of environmental problems that adversely affects the growth and development of plants. However, knowledge of lignin metabolism associated with Cu-induced phytotoxicity mechanism is insufficient. The objective of this study was to reveal the mechanisms underlying Cu-induced phytotoxicity by evaluating changes in the photosynthetic characteristics and lignin metabolism in the seedlings of wheat cultivar 'Longchun 30'. Treatment with varying concentrations of Cu clearly retarded seedling growth, as demonstrated by a reduction in the growth parameters. Cu exposure reduced the photosynthetic pigment content, gas exchange parameters, and chlorophyll fluorescence parameters, including the maximum photosynthetic efficiency, potential efficiency of photosystem II (PS II), photochemical efficiency of PS II in light, photochemical quenching, actual photochemical efficiency, quantum yield of PS II electron transport, and electron transport rate, but notably increased the nonphotochemical quenching and quantum yield of regulatory energy dissipation. Additionally, a significant increase was observed in the amount of cell wall lignin in wheat leaves and roots under Cu exposure. This increase was positively associated with the up-regulation of enzymes related to lignin synthesis, such as phenylalanine ammonia-lyase, 4-coumarate:CoA ligase, cinnamyl alcohol dehydrogenase, laccase, cell wall bound (CW-bound) guaiacol peroxidase, and CW-bound conifer alcohol peroxidase, and TaPAL, Ta4CL, TaCAD, and TaLAC expression. Correlation analysis revealed that lignin levels in the cell wall were negatively correlated with the growth of wheat leaves and roots. Taken together, Cu exposure inhibited photosynthesis in wheat seedlings, resulting from a reduction in photosynthetic pigment content, light energy conversion, and photosynthetic electron transport in the leaves of Cu-stressed seedlings, and the Cu-inhibitory effect on seedling growth was related to the inhibition of photosynthesis and an increase in cell wall lignification.
Currently, chitosan (CHT) is well known for its uses, particularly in veterinary and agricultural fields. However, chitosan's uses suffer greatly due to its extremely solid crystalline structure, it is insoluble at pH levels above or equal to 7. This has sped up the process of derivatizing and depolymerizing it into low molecular weight chitosan (LMWCHT). As a result of its diverse physicochemical as well as biological features which include antibacterial activity, non-toxicity, and biodegradability, LMWCHT has evolved into new biomaterials with extremely complex functions. The most important physicochemical and biological property is antibacterial, which has some degree of industrialization today. CHT and LMWCHT have potential due to the antibacterial and plant resistance-inducing properties when applied in crop production. This study has highlighted the many advantages of chitosan derivatives as well as the most recent studies on low molecular weight chitosan applications in crop development.
Stripe rust instigated by Puccinia striiformis f. sp. tritici causes major yield loss in wheat In this study, disease resistance was induced in wheat by pre-activation of pathogenesis related (PR) genes using two different nano-formulations (NFs) i.e. Chitosan- Salicylic acid (SA) NFs (CH-NFs) and Zinc sulphate NFs (Zn-NFs). These NFs were synthesized using green approach and were characterized using various techniques. Both NFs effectively controlled stripe rust in wheat genotypes (WH 711 and WH 1123) by significantly increasing activities of phenylalanine ammonia lyase, tyrosine ammonia lyase and polyphenol oxidase enzymes when compared with disease free-control and diseased plants. Total soluble sugar (TSS) level was highest in CH–NF treated plants. TSS was also relatively higher in diseased plants than disease free-control as well as Zn–NF treated plants. Both CH-NFs and Zn-NFs induced the expression of PR genes. In CH–NF treated plants, the relative expression of PR genes was higher on the 3rd day after spraying (DAS) of NFs as compared to diseased and Zn–NF treated plants in both the genotypes. While in case of Zn–NF treated plants, relative expression of PR genes was higher on 5th DAS as compared to diseased and disease free-control plants. Early rise in expression of PR genes due to NF treatments was responsible for disease resistance in both the wheat genotypes as evidenced by a lower average coefficient of infection. These NFs can be synthesized easily with low cost input, are eco-friendly and can be effectively used against yellow rust as well as other wheat diseases.
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.
Plants are sessile organisms and thus have to face different abiotic and biotic stresses without any chance of avoiding them. Abiotic or environmental stress such as drought, heat and salinity stresses affects plant growth and development activities resulting in drastic decreases in productivity. Drought stress induces physiological and biochemical changes in plants, such as reducing cell water potential and the stomatal closure, leading to a decrease in CO2 availability for plants leading to photosynthesis inhibition. Moreover, drought stress causes oxidative damage to plant cells via increasing reactive oxygen species (ROS), which causes damage to important cellular components, such as thylakoids and chloroplasts. Plants possess defense mechanisms to cope with increased ROS levels via producing nonenzymatic antioxidants and enzymatic antioxidants. Chitosan is a natural nontoxic, biodegradable polymer, which considered an effective biostimulant and elicitor in agriculture. In addition, these molecules, are easily obtainable from crustacean shells and the cell wall of many fungi. Chitosan has the ability to improve plant growth, productivity and tolerance to various stresses such as drought stress. Nanotechnology has emerged as a growth strategy, scientists have used chitosan-based nanomaterials in a lot of materials to improve their efficiency and biocompatibility. A natural biopolymer, chitosan, coupled with nanotechnology could offer a sustainable alternative in increasing plant tolerance to drought stress, crop improvement to the use of conventional agrochemicals towards a safer agriculture industry.
Phenolic compounds are one of the wholesome substances of mung bean sprouts, showing numerous health-promoting functions. Here, effects of sucrose on phenolic compounds profiles of mung bean sprouts were investigated. Results showed that the content and composition of phenolic compounds were significantly altered by 1‰ and 5‰ sucrose, respectively. The antioxidant capacity was significantly improved by sucrose. Based on metabolomics, 251 metabolites were detected, of which 106 were phenolic compounds. Correlation analysis showed 21 phenolics were positively correlated with antioxidant capacity. The changes in phenolic composition and antioxidant capacity after sucrose treatment were mainly due to the enrichment of phenolic biosynthesis pathways. Moreover, the gene expression and enzyme activity analysis of key phenolic biosynthetic genes contributed to elucidate the phenolic profile under sucrose treatment. In summary, mung bean sprouts are promising sources of dietary phenolic compounds and sucrose treatment is a good process to produce phenolic-rich mung bean sprouts.
Chitosan is a biopolymer derived from chitin in crustaceans. It has emerged as bio-stimulant and elicitor in agriculture sector. It is non-toxic, biodegradable and abundant in nature with potent role in regulating plant physiological aspects. Application of chitosan in the form of nanoparticles (NPs) to promote growth and development of plant is a recent topic of interest amongst researchers. It is known to protect photosynthetic machinery during abiotic stress in plants. It mitigates toxicity symptoms in plant under abiotic stresses via induction of antioxidant defence system. Chitosan NPs are known to induce plants innate immunity responses via up-regulation of defence related genes as well as elevation of secondary metabolites. The present chapter sheds some light on recent development associated with chitosan NPs-mediated modifications of plant physiology and mainly on the abiotic stress responses in plants which could prove useful for crop improvement programs in the near future.
امروزه کاربرد کیتوزان بهعنوان یکی از هورمونهای گیاهی در افزایش مقاومت گیاهان به تنشهایی همچون خشکی افزایشیافته است.
بهمنظور ارزیابی تأثیر سطوح مختلف کیتوزان بر فعالیت آنزیمهای پاداکسنده (آنتیاکسیدان) در گیاه دارویی زنیان در شرایط تنش
خشکی آزمایشی بهصورت کرتهای خردشده در قالب طرح بلوکهای کامل تصادفی با سه تکرار در سال 1393در ایستگاه تحقیقاتی
دانشگاه زابل اجرا شد. خشکی بهعنوان عامل اصلی در سه سطح ) 50 (A1میلیمتر تبخیر (شاهد)، ) 100 (A2میلیمتر تبخیر (تنش
متوسط) و )150 (A3میلیمتر تبخیر (تنش شدید) از تشتک تبخیر کلاس Aو سطوح مختلف محلولپاشی کیتوزان (شاهد، ،0/5 ،0/1
2 ،1گرم در لیتر) بهعنوان عامل فرعی در نظر گرفته شد. در این پژوهش با افزایش دور آبیاری بر میزان فعالیت آنزیمهای کاتالاز،
پراکسیداز، آسکوربات پراکسیداز، گایاکول پراکسیداز و پلی فنول اکسیداز نیز افزوده گشت. تیمار شاهد و تنش متوسط در بیشتر
فراسنجه (پارامتر)ها اختلاف معنیداری از نظر آماری نداشتند اما در سطح تنش شدید بیشترین فعالیت آنزیمها مشاهده شد. استفاده از
کیتوزان در سطوح مختلف باعث بهبود بخشیدن فعالیت آنزیمهای پاداکسنده شد بهطوریکه اثر متقابل سطوح 0/5گرم در لیتر کیتوزان
و تنش خشکی شدید توانست بیشتر فراسنجهها را نسبت به شاهد افزایش قابل توجه دهد.
Lignans along with their special ecological role in plants have received much attention in recent decades due to their anti-cancer properties. However, the mechanisms regulating their biosynthesis are still largely unknown. Here, we investigated the potential role of certain signaling pathways and their relationships in regulating the biosynthesis of 6-methoxypodophyllotoxin (6MPTOX) through pharmacological approaches in chitosan-exposed Linum album cells. The HPLC results revealed that chitosan (100 mg L⁻¹) induces 6MPTOX biosynthesis. Chitosan also elevated the content of second messengers cytosolic free Ca²⁺, hydrogen peroxide (H2O2) and nitric oxide (NO) by activating plasma-membrane Ca²⁺ channels, NADPH oxidase and nitrate reductase (NR)/nitric oxide synthase (NOS)-like enzymes, respectively. Co-application of chitosan with EGTA, W-7, imidazole, L-NAME and tungstate inhibitors diminished phenylalanine ammonia-lyase (PAL), pinoresinol-lariciresinol reductase (PLR) and 6MPTOX induction, indicating that Ca²⁺/CaM, H2O2 and NO are involved in regulating this biosynthetic pathway. Our data suggest that there is a reciprocal relationship between chitosan-induced cytosolic free Ca²⁺ and H2O2 rising , while NO production is unilaterally regulated by Ca²⁺ and H2O2. Besides, we found that chitosan also increases salicylic acid (SA) content and correspondingly, exogenous SA stimulates 6MPTOX production by affecting PAL and PLR activity. The level of SA was mutually associated with cytosolic free Ca²⁺, H2O2 and NO. Real-time PCR results suggest that mitogen-activated protein kinase 6 (MAPK6) acts downstream of second messengers and SA signaling pathways, therefore, it can be a point of integration for signals modulating lignan biosynthesis. Overall, our findings provide new insights into the lignan biosynthesis regulation, wherein Ca²⁺/CaM, H2O2 and NO signals are mediated, amplified and converged by SA and MAPK6, and the information is passed on to potential downstream targets.
The present study was undertaken to investigate the role of potassium nitrate in the modulation of phenolic metabolism and glutathione detoxification pathway in contrasting maize genotypes, with differential response towards waterlogging stress. Waterlogging led to a higher increase in the peroxidase, polyphenol oxidase, phenylalanine ammonia lyase, tyrosine ammonia lyase, glutathione-S-transferase, and glutathione peroxidase activities in seedlings of the tolerant genotype, I 172 as compared to the susceptible one, LM 11. Acid and alkaline protease activities were increased in roots and shoots of both the genotypes, though, I 172 seedlings showed lower protease activity than LM 11, under stress conditions. The contents of phenols, flavonoids, ortho-dihydroxyphenols and reduced glutathione were increased in seedlings of both the genotypes. The content of H2O2 and MDA were higher in LM 11 seedlings, under stress conditions. Foliar application of KNO3 further increased the peroxidase, polyphenol oxidase, phenylalanine ammonia lyase and tyrosine ammonia lyase activities in roots and shoots of both the genotypes with a parallel increase in the content of phenolic compounds. It reduced glutathione-S-transferase, glutathione peroxidase and protease activities in roots and shoots of waterlogged seedlings of both the genotypes. With the foliar treatment of potassium nitrate, the contents of GSH, H2O2 and MDA decreased in roots and shoots of I 172 seedlings at both the growth stages. It may be suggested that both K⁺ and NO3⁻ ions have a significant role in improving the phenolic metabolism and glutathione detoxification pathway leading to the enhanced tolerance of maize towards waterlogging stress.
Late blight, caused by the oomycete Phytophthora infestans, is one of the most devastating diseases that results in huge losses of potato crops worldwide. Chitosan as a defence elicitor can induce plant innate immunity against pathogen infection, but the efficiency and specific defence mechanism of chitosan against late blight in potato have not been elaborated. In this study, we demonstrated that the application of chitosan significantly enhanced potato resistance and reduced P. infestans infection in potted potato and in the field. Large-scale transcriptomic analysis suggested that chitosan preferentially activated several important pathways related to the plant defence response. Notably, we revealed that chitosan triggered pattern-triggered immunity responses in potato. Chitosan could trigger pattern recognition receptors to initiate intracellular signalling, and gradually amplify the immune signal. qRT-PCR verification showed that chitosan induced the expression of defence-related genes in potato. Moreover, treatment with chitosan result in Induced Systemic Resistance (ISR) in potato, including an accumulation of plant hormone salicylic acid, increase in the level of phenylalanine ammonia lyase activity and a content decrease of malondialdehyde. These findings help elucidate chitosan-mediated activation of the immune system in potato and provide a potential ecofriendly strategy to control potato late blight in the field.
There are two clear and pressing drivers for the development of renewable fuel sources: peak extraction of fossil fuel oil and global climate. Biofuels, including biodiesel, can help manage both. While ethanol from sugar (largely sugar cane) and from starch (largely corn) can provide an important fuel source for light surface vehicles, it is not suitable for long-haul heavy transport or the aerospace sector. Although oil content is a complex trait, marker-assisted plant breeding and focused molecular genetics can increase the oil yield per hectare and could lead to development of plants producing hydrocarbons directly utilizable in biodiesel, in addition, the development of low-input systems, able to rely on bio-inputs (biofertilizers and biochar) and less on energy-intensive chemical inputs, can improve the energy ratio of biodiesel production (yield of bioenergy per unit input of fossil fuel energy) and allow production of biodiesel feedstocks on what are currently poorer soils. The development of improved chemical or biological methods for converting the oils produced can lead to more efficient production of biodiesel. Although properties such as cloud point and the emissions from engines utilizing biodiesel must be better understood, biodiesel can be used as an effective transport fuel.
Hydrogen peroxide (H2O2) generated in response to wounding can be detected at wound sites and in distal leaf veins within 1 hr after wounding. The response is systemic and maximizes at about 4-6 hr in both wounded and unwounded leaves, and then declines. The timing of the response corresponds with an increase in wound-inducible polygalacturonase (PG) mRNA and enzyme activity previously reported, suggesting that oligogalacturonic acid (OGA) fragments produced by PG are triggering the H2O2 response. Systemin, OGA, chitosan, and methyl jasmonate (MJ) all induce the accumulation of H2O2 in leaves. Tomato plants transformed with an antisense prosystemin gene produce neither PG activity or H2O2 in leaves in response to wounding, implicating systemin as a primary wound signal. The antisense plants do produce both PG activity and H2O2 when supplied with systemin, OGA, chitosan, or MJ. A mutant tomato line compromised in the octadecanoid pathway does not exhibit PG activity or H2O2 in response to wounding, systemin, OGA, or chitosan, but does respond to MJ, indicating that the generation of H2O2 requires a functional octadecanoid signaling pathway. Among 18 plant species from six families that were assayed for wound-inducible PG activity and H2O2 generation, 14 species exhibited both wound-inducible PG activity and the generation of H2O2. Four species, all from the Fabaceae family, exhibited little or no wound-inducible PG activity and did not generate H2O2. The time course of wound-inducible PG activity and H2O2 in Arabidopsis thaliana leaves was similar to that found in tomato. The cumulative data suggest that systemic wound signals that induce PG activity and H2O2 are widespread in the plant kingdom and that the response may be associated with the defense of plants against both herbivores and pathogens.
Both phenylalanine ammonia lyase and tyrosine ammonia lyase were detected in tobacco (Nicotiana tabacum L. Wisconsin 38) callus. The enzymes were separated from each other by Sephadex G-200 column chromatography. Increased activity of tyrosine ammonia lyase was observed during culture of tobacco callus under shoot-forming conditions, while activity of phenylalanine ammonia lyase increased during culture under non-organ-forming conditions. Confirmation of these findings was obtained by examining the incorporation of [(14)C]tyrosine and [(14)C]phenylalanine into p-coumarate and trans-cinnamate, respectively.
A protein determination method which involves the binding of Coomassie Brilliant Blue G-250 to protein is described. The binding of the dye to protein causes a shift in the absorption maximum of the dye from 465 to 595 nm, and it is the increase in absorption at 595 nm which is monitored. This assay is very reproducible and rapid with the dye binding process virtually complete in approximately 2 min with good color stability for 1 hr. There is little or no interference from cations such as sodium or potassium nor from carbohydrates such as sucrose. A small amount of color is developed in the presence of strongly alkaline buffering agents, but the assay may be run accurately by the use of proper buffer controls. The only components found to give excessive interfering color in the assay are relatively large amounts of detergents such as sodium dodecyl sulfate, Triton X-100, and commercial glassware detergents. Interference by small amounts of detergent may be eliminated by the use of proper controls.
A full-length cDNA encoding phenylalanine ammonia-lyase (PAL) from Zea mays L. was isolated and the coding region was expressed in Escherichia coli as a C-terminal fusion to glutathione S-transferase. After purification by glutathione-Sepharose chromatography, the glutathione S-transferase moiety was cleaved off and the resulting PAL enzyme analyzed. In contrast to PAL from dicots, this maize PAL isozyme catalyzed the deamination of both L-phenylalanine (PAL activity) and L-tyrosine (tyrosine ammonia-lyase activity). These results provide unequivocal proof that PAL and tyrosine ammonia-lyase activities reside in the same polypeptide. In spite of large differences in the Michaelis constant and turnover number of the two activities, their catalytic efficiencies are very similar. Also, both activities have the same pH and temperature optima. These results imply that maize can produce p-coumaric acid from both phenylalanine and tyrosine.
The effect of chitosan preparations with different levels of deacetylation and other polyanions on the growth of post-harvest pathogens was investigated. Chitosan markedly reduced the radial growth of all the fungi tested, with a greater effect at higher concentration. Chitosan was more effective than N,O-carboxymethylchitosan, polygalacturonate or d-glucosamine, and its inhibitory activity appeared to increase with the level of deacetylation. In addition to inducing cellular leakage of amino acids and proteins in Botrytis cinerea and Rhizopus stolonifer, chitosan also caused morphological changes in R. stolonifer. The ultrastructural study showed that chitosan caused deep erosion of the cell wall as well as increasing the cell-wall thickness. Although chitosan treatment did not affect chitin distribution in R. stolonifer wall, it stimulated the activities of chitin deacetylase, an enzyme involved in the biosynthesis of chitosan. This may well upset the balance between biosynthesis turnover of chitin, thereby rendering the cell wall more viscoelastic.
Chitin, an important component of most fungal cell walls, elicited lignification in wheat leaves when applied as a suspension to wounds. The soluble derivatives ethylene glycol, chitin and chitosan were also active, but glucosamine, N-acetylglucosamine and small chitin oligomers did not elicit the response. The fungal glucan pullulan lacked activity, but laminarin, an algal glucan, was a weak elicitor. The response could also be elicited by fungal cell wall preparations. The possible role of chitin and related wall polymers in inducing host-defence mechanisms in wheat is discussed.
Some of the more important evidence is presented which supports the view that accumulation of phytoalexins at the site of attempted infection in plants. The accumulation of phytoalexins represents only one of a number of disease-resistance mechanisms in plants. Experiments are described demonstrating that the enzymes that catalyze the synthesis of phytoalexins are themselves synthesized de novo when plant cells are exposed to microbes of other effective stimuli. Evidence is also presented showing that phytoalexins, once accumulated, are catabolized or detoxified by many microorganisms as well as by the plants themselves. Elicitors are the major concern of this review. The literature is summarized in which elicitors are shown to be not only constituents of some microbes but also to be present in the cell walls of plants. A hypothesis is presented that suggests that all of the abiotic and some of the biotic elicitors stimulate phytoalexin accumulation by causing the release of an endogenous elicitor from the cell walls of plants. 108 references, 9 figures.
The relation between the activities of lignification enzymes and deposition of cell-wall components during progressive stages of development has not been demonstrated. In this study, phenylalanine ammonialyase (PAL), tyrosine ammonialyase (TAL), and cinnamyl alcohol:NADPH dehydrogenase (CAD) activities were determined in maize (Zea maize L.) internodes at several development stages, and the activities were correlated with cellulose, hemicellulose, and lignin concentrations. Growth-chamber grown maize was harvested at the fourteenth leaf stage, enzyme activities were quantified, and cell-wall components were determined by the detergent system of fiber fractionation from the lower, middle, and upper sections of Internodes 7 through 14
Discusses the problem of response localization and localization of phenolics relative to the sequential development of stages of disease that lead to expression of resistance. New techniques in characterising phenols indicate the need to understand each disease interaction as a unique phenomenon that can rarely be considered as representative of host responses. Major sections of this review are: initial events in the host response; lignin and polymeric phenols - identification and importance; and phytoalexins - do they accumulate at the right time and place? -P.J.Jarvis
Potato (Solanum tuberosum) suspension cultures were used as a model to obtain basic information regarding the occurrence of enzymatic browning reactions. The cultures were subjected to chitosan, an established stress factor, at concentrations from 2.5 to 100 μg/mL to examine stress reactions and to pressure treatments from 100 to 400 MPa for 10 min at 25 °C to monitor the impact of minimal processing on plant systems. The release of hydrogen peroxide from chitosan or high- pressure-treated potato cells, which constitutes an initial stress response, was correlated with activities of phenylalanine ammonia-lyase (PAL), peroxidase (PO), and polyphenol oxidase (PPO) as well as with polyphenol production in cell free extracts. Chitosan-induced browning was related to PAL induction and corresponded to the concentration of phenols within the cells. Sensitivity of plant cells to these stress factors was affected by the amount of PO present in the cells. High PO levels in the potato cells resulted in a fast degradation of hydrogen peroxide and reduced PAL induction after chitosan treatment. Different degrees (reversible, irreversible) and locations (tonoplast, plasma membrane) of permeabilization of cell membranes led to polyphenol production, which was correlated to reaction rates of PPO and increased pressure treatments. Pressures higher than 150 MPa resulted in irreversible permeabilization of cell membranes and in loss of compartmentalization in the cells. Keywords: Plant cell cultures; stress response; phenylalanine ammonia-lyase; peroxidase; polyphenol oxidase; elicitation; high-pressure treatment; membrane permeabilization
An enzyme was found which catalyzes the deamination of l-tyrosine, giving equimolar amounts of trans-p-coumaric acid and ammonia as the products. This enzyme (tyrase) was readily detected in sorghum, barley, rice, wheat, oat, corn and sugar cane plants; but not in pea, lupine, alfalfa or white sweet clover plants, or in yeast. Tyrase was concentrated in the stems of barley rather than the leaves, and reached its maximum concentration at about the time the heads were emerging. The crude, soluble protein extracted from an acetone powder of barley stems was purified about forty-fold with respect to tyrase. Tyrase preparations from this source were also found to convert dl-m-tyrosine to m-coumaric acid and ammonia, and have been shown by Koukol and Conn to contain an enzyme (phenylalanase) which can catalyze the conversion of l-phenylalanine to cinnamic acid and ammonia. The data suggest that tyrase is distinct from the enzymes (or enzyme) catalyzing the deaminations of phenylalanine and m-tyrosine.
Oligomers of chitin (monomer to hexamer) and their deacetylated derivatives (monomer to tetramer) were purified from acid hydrolysates of chitin and chitosan, respectively, and assayed for lignification-eliciting activity in wounded wheat leaves. At 40 μg per wound, the chitin monomer and dimer were inactive, whist the chitin trimer possessed very slight activity. In contrast, the chitin tetramer, pentamer and hexamer all possessed significant elicitor activity. Dose-response curves indicated that the activities of the elicitor-active chitin oligomers were similar, and that their activity rapidly diminished at lower doses. Digestion of the tetramer with chitinase abolished elicitor activity. None of the deacetylated oligomers tested (monomer to tetramer) possessed any significant elicitor activity, confirming the requirement of acetyl groups for elicitor activity. The activity of the chitin tetramer was entirely dependent on the inclusion of a pre-wounding step in the assay, which explains why a previous study failed to identify an elicitor-active oligomer. Prior wounding also increased the activity of a number of other known lignification elicitors.
Primary leaves of wheat (Triticum aestivum) were examined after inoculation with avirulent and virulent strains of the leaf rust fungus (Puccinia recondita f. sp. tritici) at stages when previous work had shown fungal and host cells to be affected by the expression of the Lr20 or Lr28 alleles for resistance. Histochemical stains for lignin were first shown to react in characteristic ways with cell walls in stomata, vascular tissue and mechanical fibres in sections of uninfected leaves. Toluidine blue and two different chlorine-sulphite reagents reacted positively for lignin with walls of hypersensitive mesophyll cells in the Lr28-bearing leaves, but only toluidine blue in the Lr20-bearing leaves. Phloroglucinol did not react positively with these cells. Aniline blue stained guard cells in the infected Lr28-bearing leaves and hypersensitive cells strongly in these leaves but less so in Lr20-bearing leaves, suggesting the presence of callose. Sudan IV failed to indicate suberin in any situation. Lignin was also extracted and measured as a complex with thioglycolic acid (LTGA). LTGA derived from uninfected and infected leaves had a characteristic UV absorption spectrum with a distinctive peak at 280 nm. Lignin was present in high concentration 48 h after inoculation of Lr20-bearing leaves with an avirulent strain, when widespread hypersensitivity had occurred around fungal colonies. Lignin was also detected at moderate concentrations 24 h after inoculation of Lr28-bearing leaves with an avirulent strain, when one or a few cells had undergone hypersensitivity in the presence of haustoria. Enzymatic digestion of these leaves yielded fractions containing hypersensitive cells and the lignin content in these fractions was significantly higher than in comparable fractions from uninfected leaves. Some evidence was obtained that infection also increased the lignin content of stomatal guard cells. The results suggested that lignification, in cells undergoing a hypersensitive response, may play a rote in the highly specific cultivar resistance expressed by wheat to the leaf rust fungus.
A protein determination method which involves the binding of Coomassie Brilliant Blue G-250 to protein is described. The binding of the dye to protein causes a shift in the absorption maximum of the dye from 465 to 595 nm, and it is the increase in absorption at 595 nm which is monitored. This assay is very reproducible and rapid with the dye binding process virtually complete in approximately 2 min with good color stability for 1 hr. There is little or no interference from cations such as sodium or potassium nor from carbohydrates such as sucrose. A small amount of color is developed in the presence of strongly alkaline buffering agents, but the assay may be run accurately by the use of proper buffer controls. The only components found to give excessive interfering color in the assay are relatively large amounts of detergents such as sodium dodecyl sulfate, Triton X-100, and commercial glassware detergents. Interference by small amounts of detergent may be eliminated by the use of proper controls.
Binding experiments using a 125I-labeled tyramine conjugate of N-acetylchitooctaose, a highly potent elicitor for the induction of phytoalexin production in rice cells, and a microsomal membrane preparation from suspension-cultured rice cells showed the presence of a novel high-affinity binding site for this oligosaccharide. The binding of the ligand was saturable and the Scatchard plot analysis of the results indicated the presence of a single class of binding site with a Kd of 5.4 nM which is comparable with that reported for the binding of the hepta-beta-glucoside elicitor in soybean membrane. The ligand binding was inhibited by unlabeled N-acetylchitoheptaose but not by its deacetylated form. These characteristics of this binding site coincide well with the specificity and sensitivity for the elicitor in several assay systems, suggesting the possible involvement of this binding site in the recognition of the elicitor in vivo.
A full-length cDNA encoding phenylalanine ammonia-lyase (PAL) from Zea mays L. was isolated and the coding region was expressed in Escherichia coli as a C-terminal fusion to glutathione S-transferase. After purification by glutathione-Sepharose chromatography, the glutathione S-transferase moiety was cleaved off and the resulting PAL enzyme analyzed. In contrast to PAL from dicots, this maize PAL isozyme catalyzed the deamination of both L-phenylalanine (PAL activity) and L-tyrosine (tyrosine ammonia-lyase activity). These results provide unequivocal proof that PAL and tyrosine ammonia-lyase activities reside in the same polypeptide. In spite of large differences in the Michaelis constant and turnover number of the two activities, their catalytic efficiencies are very similar. Also, both activities have the same pH and temperature optima. These results imply that maize can produce p-coumaric acid from both phenylalanine and tyrosine.
Chitosan treatment (2-8 mg/mL) of wheat seeds significantly improved seed germination to recommended seed certification standards (>85%) and vigor at concentrations >4 mg/mL, in two cultivars of spring wheat (Norseman and Max), by controlling seed-borne Fusarium graminearum infection. The germination was <80% in the control and >85% in benomyl- and chitosan-treated seeds. Seed-borne F. graminearum was reduced to >50% at higher chitosan treatments compared to the control. Synthesis of phenolic acids was stimulated in primary leaves following chitosan treatment, and levels of these phenolic acids, especially ferulic acid, increased significantly with increasing chitosan concentration. Lignin content of primary leaves also showed a similar pattern. The synthesis of precursors of lignin such as p-coumaric, ferulic, and sinapic acids and phenolic acids having antimicrobial activity such as benzoic, p-coumaric, caffeic, protocatechuic, chlorogenic, ferulic, and gallic acids was also stimulated by chitosan treatment. The induction of phenolic acids and lignin was significantly lower in cv. Max compared to Norseman. Chitosan also inhibited fungal transmission to the primary roots of germinating seedlings. Results suggest that chitosan controlled seed-borne F. graminearum infection and increased the resistance in seedlings by stimulating the accumulation of phenolics and lignin. Thus, chitosan has a potential for improvement of seed quality and enhancement of crop yields as well as increased value of stored grains for food and feed.
Soluble chemical derivatives of chitin and chitosan including ethylene glycol chitin, nitrous acid-modified chitosan, glycol chitosan, and chitosan oligomers, produced from chitosan by limited hydrolysis with HCl, were found to possess proteinase inhibitor inducing activities when supplied to young excised tomato (Lycopersicon esculentum var Bonnie Best) plants. Nitrous acid-modified chitosans and ethylene glycol chitin exhibited about 2 to 3 times the activity of acid hydrolyzed chitosan and 15 times more activity than glycol chitosan. The parent chitin and chitosans are insoluble in water or neutral buffers and cannot be assayed. Glucosamine and its oligomers from degree of polymerization = 2 through degree of polymerization = 6 were purified from acid-fragmented chitosan and assayed. The monomer was inactive and dimer and trimer exhibited weak activities. Tetramer possessed higher activity and the larger pentamer and hexamer oligomers were nearly as active as the total hydrolyzed mixture. None of the fragments exhibited more than 2% acetylation (the limits of detection). The contents of the acid-fragmented mixture of oligomers was chemically N-acetylated to levels of 13% and 20% and assayed. The N-acetylation neither inhibited nor enhanced the proteinase inhibitor inducing activity of the mixture. These results, along with recent findings by others that chitinases and chitosanases are present in plants, provide further evidence for a possible role of soluble chitosan fragments as signals to activate plant defense responses.
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