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Association of enhanced peroxidase activity with induced systemic resistance of cucumber to Colletotrichum lagenarium
Abstract
Inoculation of the first true leaf of cucumber with Colletotrichum lagenarium enhanced peroxidase activity in leaf 2. The increased activity was associated, at least in part, with the fastest moving anodic isozymes during polyacrylamide gel electrophoresis. All plant parts and cellular fractions exhibited enhanced peroxidase activity in protected as compared to control plants. Injury of leaf 1 with dry ice neither induced systemic resistance to C. lagenarium nor enhanced peroxidase activity of leaf 2. Inoculation of leaf 1 with C. lagenarium followed by inoculation of leaf 2, 1 week later, elicited a higher degree of protection and higher peroxidase activity in leaf 3 than did single inoculations. Increasing numbers of C. lagenarium lesions on leaf 1 progressively increased peroxidase activity and resistance in leaf 2. Induced resistance was detected 3 to 4 days after inoculation of leaf 1, whereas peroxidase activity increased after the 4th day.
... POX activity was expressed as changes in absorbance at 470 nm at 30s intervals during 2 minutes since the reaction occurred as the rate of conversion of tetraguaiacol and guaiacol using the method described by Hammerschmidt et al. (1982) and Khoa et al. (2017). ...
... Flavonoids, isoflavonoids, and other phenolic compounds are generally secondary metabolites in plants with a wide variety of chemical structures. Thus they have many functions such as antioxidant and plant protection against pathogens by activating a hypersensitive response or inhibiting important enzymes of the pathogens (Hammerschmidt et al., 1982;Mierziak et al., 2014;Nicholson and Hammerschmidt, 1992;Van Loon et al., 2006, 1998. Therefore, the activity of PAL rapidly increases at 2 and 3 DAI (Figure 7) would promote the biosynthesis of the metabolic compounds; thereby helping to prevent the infection of Xoo into rice leaf tissue. ...
This study aims at evaluating the disease-reducing effects against rice bacterial leaf blight (Xanthomonas oryzae pv. oryzae). Under greenhouse conditions, the activities of the four enzymes [peroxidase (POX), catalase (CAT), polyphenol oxidase (PPO) and phenylalanine ammonia lyase (PAL)] after application of Kalanchoe pinnata aqueous leaf extracts using the combination of seed soaking and foliar spraying were studied. Overall, two extract concentrations [1 and 2% (w/v)] applied as seed soaking combined with the five extract concentrations [1, 2, 3, 4 and 5% (w/v)] applied as foliar spraying were tested. Three application methods were furthermore used for foliar spraying (7 days before pathogen inoculation (DBI), 14 DBI and their combination). Results showed the effects increased with the increase of extract concentrations and durations from application time points prior to pathogen inoculation. The combination of foliar spraying at 7 and 14 DBI provided stronger protection compared to single sprays. The effects involved induced resistance. Indeed, the activities of POX and CAT increased until 4 days after inoculation (DAI) and remained until 7 DAI, while those of PPO and PAL increased similarly then decreased until 7 DAI. Activities of these enzymes increased after pathogen inoculation and reached higher levels with extract applications.
... hours. The enzyme activity was expressed as changes in absorbance/min/g fresh weight (Hammerschmidt et al. 1982). Three replicates were maintained for each treatment. ...
ABSRACT
Dry root rot of chickpea caused by Macrophomina phaseolina is emerging as the most destructive constraint to chickpea productivity and production in the changed scenario of climate when growing crop is predisposed to high temperature and moisture stress. Keeping in view the importance of the disease, present investigations on M. phaseolina were undertaken during Rabi, 2020-21 with
the objectives viz., surveying of incidence of dry root rot, isolation, identification and
pathogenicity, in- vitro management by biocontrol agents and induction of systemic
resistance at the department of Plant Pathology, College of Agriculture, VNMKV,
Parbhani.
The survey of chickpea dry root rotin Parbhani tehsil revealed that average disease incidence and intensity was 5.1 per cent and 11.15 per cent, respectively. The mean highest dry root rot incidence was observed in Parwa (9.48%) village. Further, Local cultivar was found to be highly susceptible to the disease (8.1%) followed by Vijay and Digvijay was found to be suffer less with the disease (2.1%). Seed treatment plays great role in reducing disease incidence, as an average 1.6 per cent disease incidence in seed treated fields and 6.5 per cent for non-seed treated fields was observed. Soil moisture status determines the disease incidence as more average disease incidence was observed in moisture deficient soils (6.76%) and (2.2%) was observed in irrigated fields.
The pathogen M. phaseolina was successfully isolated on Potato dextrose agar by standard tissue isolation technique from the naturally infected chickpea plant parts collected during survey. The pathogenicity of the test pathogen was proved on susceptible chickpea cv. JG- 62 under greenhouse conditions. Based on symptomatology, cultural and morphological characteristics, microscopic
observations and pathogenicity test the test pathogen was identified as M. phaseolina and its further identity was confirmed.
The lowest one percent disease incidence was observed in Trichoderma asperellum @ 5 g/kg treated seeds. The both Trichoderma asperellum and Pseudomonas fluorescens improved seed germination, enhanced root-shoot length and vigour and thereby reduced disease incidence significantly.
Infection by pathogens brings about a lot of changes in biochemical
processes in the host plant. Biochemical changes associated with dry root
development in chickpea i.e., changes in quantity of phenols, activity of enzymes
(chitinase, peroxidase, polyphenol oxidase) were observed after treatment with
biocontrol agents which leads to suppression of pathogen activity and thereby
reduction of disease effectively, as it indicates the induction of systemic resistance in chickpea plants against M. phaseolina.
(Keywords: Dry root rot, Chickpea, Macrophomina phaseolina, Trichoderma
asperellum, Pseudomonas fluorescens, Induction of systemic resistance)
... hours. The enzyme activity was expressed as changes in absorbance/min/g fresh weight (Hammerschmidt et al. 1982). Three replicates were maintained for each treatment. ...
... The OD was measured at 240 nm. Guaiacol was used as a substrate to quantify POD activity [41]. A 6 mL reaction mixture contained 0.1 M H 2 O 2 , 0.25% guaiacol, and 0.2 mL enzyme extract in 10 mM sodium phosphate (pH 7.4). ...
Citation: Akram, W.; Khan, I.; Rehman, A.; Munir, B.; Guo, J.; Li, G.
... The activities of SOD, POD, CAT, and APX were determined using a spectrometer at 560, 470, 240, and 290 nm, respectively [67][68][69][70]. The osmolyte contents of soluble sugar, protein, MDA, and Pro were determined with the methods of phenolsulfuric acid, coomassie brilliant blue colorimetric, thiobarbituric acid, and sulfosalicylic acid-acid ninhydrin, respectively [71][72][73][74]. ...
Peganum harmala L. is a perennial herbaceous plant that plays critical roles in protecting the ecological environment in arid, semi-arid, and desert areas. Although the seed germination characteristics of P. harmala in response to environmental factors (i.e., drought, temperature, and salt) have been investigated, the response mechanism of seed germination to drought conditions has not yet been revealed. In this study, the changes in the physiological characteristics and transcriptional profiles in seed germination were examined under different polyethylene glycol (PEG) concentrations (0–25%). The results show that the seed germination rate was significantly inhibited with an increase in the PEG concentration. Totals of 3726 and 10,481 differentially expressed genes (DEGs) were, respectively, generated at 5% and 25% PEG vs. the control (C), with 1642 co-expressed DEGs, such as drought stress (15), stress response (175), and primary metabolism (261). The relative expression levels (RELs) of the key genes regulating seed germination in response to drought stress were in accordance with the physiological changes. These findings will pave the way to increase the seed germination rate of P. harmala in drought conditions.
... Additionally, the plant enzymes namely, glutathione Stransferases, phenoloxidase, and peroxidase were determined according to the methods of [15,16,17,18,19]. The tested plant enzymes and phytochemical leaf components were analyzed and determined at Chemical Analysis Constituent, Insect Physiology Dept., Plant Protection Research Institute. ...
... According to the method described by Hammerschmidt et al. [36], the peroxidase activity was assessed. About 1.5 mL of pyrogallol (0.05 M) and 100 µL of enzyme extract were added to a spectrometer sample cuvette. ...
Some of the significant globally prevalent vector-borne illnesses are caused by Culex pipiens. Synthetic pesticides have been widely utilized to eradicate C. pipiens, which has led to a number of health risks for people, insect resistance, and environmental contamination. Alternative strategies are therefore vitally needed. In the current investigation, the Trichoderma viride fungal culture filtrate was used to create selenium and silver nanoparticles (SeNPs and AgNPs, respectively) and test them on C. pipiens larvae in their fourth instar stage. The death rate increased significantly when SeNP and AgNP concentrations increased, according to the results. SeNPs and AgNPs significantly affected the developmental and detoxification enzymes in fourth instar larvae of C. pipiens at 24 h after being treated with the sublethal concentration of the tested NPs. As a result of their insecticidal effect on C. pipiens larvae, SeNPs and AgNPs are considered effective and promising larvicidal agents.
... APX activity was calculated as 2 0 9 nanomoles of ascorbate oxidized per minute per gram of fresh weight (n mole ascorbate 2 1 0 oxidised min − 1 g − 1 fresh wt.). The activity of the defense enzymes phenylalanine ammonia lyase (PAL) and peroxidase 2 1 4 (POX) was quantified following the methods described in our previous research paper (1955) and Hammerschmidt (1982). ...
Plants encounter numerous biotic and abiotic challenges, with biotic stresses significantly limiting wheat productivity. Competition for nutrients and space among plants adds another layer of stress. Defence priming is a promising approach to enhancing plant protection against these environmental stresses. This study explores BABA (beta-aminobutyric acid) priming in wheat against Bipolaris sorokiniana under varying degrees of competition. We assessed growth parameters, disease phenotype, biochemical changes, and yield-related traits in both primed and non-primed wheat under disease pressure and competition. Our findings revealed that growth parameters declined in both primed and non-primed wheat as competition increased. However, primed wheat showed better morphological growth than non-primed wheat at each competition level. Under disease pressure, primed wheat demonstrated protection comparable to non-challenged plants at all competition levels, while non-primed plants were susceptible. Non-primed wheat under high-density (HD) conditions exhibited the highest disease susceptibility due to intense competition. BABA-primed plants showed better disease protection at each competition level compared to non-primed plants. BABA priming allowed plants to mitigate competition effects and maintain a consistent defence response. The yield performance of primed wheat was superior to that of non-primed wheat across all competition levels. Our research suggests BABA priming as an effective pesticide-free strategy for crop protection against pathogens under competitive conditions.
... Peroxidase Activity (POX EC 1.11.1.11) Peroxidase activity was determined using Hammerschmidt et al.'s [39] method. The reaction mixture contained 2.9 mL of sodium phosphate buffer (0.01 M) with guaiacol (0.25%) and hydrogen peroxide (0.1 M) at a pH of 6.0. ...
Drought, exacerbated by climate change, represents a growing challenge for agriculture, significantly impacting on crops such as chili peppers (Capsicum), essential in the global diet. This work evaluated the response to water stress by suspending irrigation in Siete Caldos chili pepper plants (Capsicum frutescens). Control plants were watered every 48 h, while stress was induced in the test plants by withholding irrigation for 14 days, followed by an evaluation of recovery through rehydration on day 15. Growth parameters such as the fresh weight of the aerial part, root length, and number of flower buds showed significant differences between the two groups from the eighth day onwards. However, physiologically and biochemically stress-induced decreased relative water content, membrane stability, and chlorophyll content, coupled with increased electrolyte leakage, proline content, and antioxidant activity (catalases and peroxidases), were observed starting on the third day. These effects were more severe on day 14. At the molecular level, the expression of stress response genes (AP2, LOX2, CAT, CuSOD, MnSOD, and P5CS) was quantified at days 3, 14, and 15, revealing differences in transcript levels between the treatments. Finally, rehydration in the stressed plants resulted in the recovery of the evaluated parameters and a survival rate of 100%. Therefore, chili pepper has tolerance mechanisms that allow it to withstand a period of 14 days without irrigation, without reaching its permanent wilting point, and it can recover if conditions improve. This study underscores the complexity of plant responses and tolerance mechanisms to drought, providing insights into the behavior of semi-domesticated species.
... Peroxidase (POX; EC 1.11.1.7), according to Hammerschmidt et al. (1982) using a spectrophotometer at 470 nm and Glutathione-s-transferase (EC 2.5.1.13) determined by the method of Habig and Jakoby (1981) at 340 nm. ...
Purpose
Medicinal plants show a relevant importance in human life and health. The use of natural substances in crop management is not only significant for the plant healthy growth and yield, but also for obtaining safe products. The study aimed to examine the effect of seaweed extract (SW) as a natural source of nutrition and salicylic acid (SA) on plant health, physiology and essential oil profile of French marigold ( Tagetes patula L.).
Methods
Three levels of salicylic acid, SA50, SA100 and SA200, (50, 100, and 200 mg L − 1 ) and three levels of seaweed extract, SW2, SW4 and SW6 (2.0, 4.0, and 6.0 ml L − 1 ), in comparison with control treatment (tap water) were applied as foliar sprayings. The seven treatments were arranged in randomized complete block design and were replicated thrice in two growing seasons (2020 and 2021).
Results
Findings pointed out that SA200 increased plant height, branches number plant − 1 , stem diameter, leaf area, leaves number plant − 1 , plant fresh weight, and plant dry weight by 32.9, 112.2, 59.2, 34.4, 44.3, 33.0 and 56.9% (averages of the two seasons), respectively, compared to the control treatment (tap water). SW6 increased carotenoids content by 34.8 and 46.4% in 2020 and 2021 seasons, respectively. Salicylic acid at the rate of 200 mg L − 1 along seaweed extract at 6 ml L − 1 gave the highest values of total sugars and free amino acids. SA200 alone recorded the maximal value of peroxidase activity surpassing the other treatments. SW6 possessed the greatest essential oil content in both seasons, statistically equaling SA200 in the first season. Huge variations in essential oil profile were recorded under the tested trial treatments.
Conclusion
It could be concluded that salicylic acid and seaweed extract foliar application unveiled their involvement in diverse physiological and developmental responses; pigment formation, enzyme activities, flower induction, nutrient uptake, essential oil metabolism, and overall plant growth and development. It is recommended to use the highest concentrations of the tested substances (SA at 200 mg L − 1 or SW at 6.0 ml L − 1 ) for achieving distinctive improvements in physiological responses of French marigold plant.
... Examples include accumulation of phytoalexins [32,33]. Likewise, the hypersensitive response as well as reinforcement of plant cell walls appear to be positively correlated to the reduction of pathogen penetration and this effect is mediated by papilla formation and accumulation of callose, lignin, phenolic compounds, H 2 O 2 and silicon at the sites of attempted penetration [30,31,[33][34][35][36][37]. Accumulation of PR-proteins like peroxidase, chitinase and β-1,3-glucanase has also been reported as an important mechanism [29,31,[37][38][39][40]. ...
Imbibing watermelon seeds in 1 mM sodium tetraborate (Na2B4O7) for 24 h systemically protected plants against foliar infection by Stagonosporopsis cucurbitacearum in detached leaves and under greenhouse conditions. The treatment resulted in both a reduction in the overall percentage of leaf infection as well as in the size of lesions. Studies of the mechanisms by which Na2B4O7 protected watermelon showed that there was no direct effect on the S. cucurbitacearum mycelium growth in vitro. On the other hand, plants raised from seeds primed with Na2B4O7 showed a higher frequency of fluorescent epidermal cells compared to the plants treated with water. This indicates that a higher number of cells expressed the hypersensitive response after Na2B4O7 priming. In addition, there was an increase in peroxidase activity and an enhanced accumulation of a 45 kDa acidic peroxidase isoform during the early stages of infection in plants treated with Na2B4O7 compared to plants treated with water and this was positively correlated to the reduction of leaf infection caused by the pathogen. These results indicate that Na2B4O7 is able to induce systemic resistance in watermelon against S. cucurbitacearum by activating the hypersensitive reaction at penetration sites, increasing peroxidase activity and altering the peroxidase isozyme profile. Although each individual response may only have had a minor effect, their combined effects had a reducing effect on the disease.
... The leaves of the test plants were isolated at different time intervals post inoculation, 0, 2, 4, 24, 48, 72, 96, 120 and 144 h. PO was estimated by pyrogallol based method of Hammerschmidt et al. [25] and PPO by Mayer and Harel [26], observing absorbance at 420 and 490 nm spectrophotometrically. Enzyme levels were expressed in min/gFW. ...
Background
Seaweeds contain a widespread range of fatty acids (FA), and several of them have potential bioactivity. FAs are dynamic members of all biota, as well as being acknowledged for their critical function in initiating phytohormone interactions and acting as important participants in many defense signalling pathways of the plant system. The current study looks at the defense-eliciting potentials of fatty acids from the green seaweed Chaetomorpha antennina (Bory) Kützing and their impact on the polyphagous insect pest Spodoptera litura (Fab).
Results
The seaweed was detected with 19 fatty acids, with larger proportion of hexa and octadecanoic and linoleic acids. The algal fatty acid compounds (CFA) were successful in eliciting salicylic acid and phenolic compounds biosynthesis along with defense enzymes peroxidase (PO) and polyphenol oxidase (PPO). CFA enhanced the synthesis of defense enzymes, PO and PPO and phenols, post infestation with S. litura (> 50%) compared to control plants exposed to the pest. CFA was also effective in causing direct mortalities (96–98%) to the larvae (II-V instars). S. litura larvae exposed to elicited tomato plants displayed physiological incursions that extended larval-pupal duration to 26–28 days, preventing both morphogenetic transitions as well as affecting their morphology, that lead to the emergence of adults with malformed wings, legs. As a consequence, the fecundity was reduced by 60% affecting the reproductive performances of second-generation adults. The consumption rate (RCR) of larvae exposed to CFA was decreased by 84%, depicting feeding deterrence. These larvae were also observed with > 50% reduction in the levels of phosphatase enzyme secretion, bringing down larval growth rate from 0.58 to 0.34 mg/day. Histological analysis of exposed larvae displayed midgut cell disruption.
Conclusion
Hence, the study finally confirms the elicitor potentials of fatty acid compounds from C. antennina, by inducing natural systemic defenses. This investigation unlocks novel forecasts besides delivering an unconventional method for crop protection to moderate or interchange the solicitation of chemical pesticides.
Graphical Abstract
... This was conducted according to Hammerschmidt et al. (1982). The reaction mixture included 1.5 ml of 0.05M pyrogallol, 0.5 ml of the enzyme extract, and 0.5 ml of 1% H2O2. ...
... Peroxidase activity (EC1.11.1.7) was ascertained in line with the method suggested by Hammerschmidt et al. [32] and expressed as units of peroxidase/mg protein. ...
Saline water has been proposed as a solution to partially supply plants with their water requirements due to a lack of fresh water for cultivation in arid and semi-arid sites. Gamma-aminobutyric acid (GABA) is a non-protein amino acid participating in numerous metabolic processes to mitigate the undesirable effects of salinity. A pot experiment was carried out during 2021 and 2022 at Sakha Horticulture Research Station to investigate the effect of foliar application of GABA at 20 and 40 mM on vegetative growth and biochemical changes in French lavender under increasing levels of sea water salinity irrigation treatments (0, 1000, 2000, and 3000 ppm). Results indicated that increasing salinity concentration noticeably decreased plant height, number of branches, herb fresh and dry weight, root length, root fresh and dry weights, photosynthetic pigments, relative water content, and essential oil percentage. On the other hand, accumulation of proline and antioxidant enzymes was increased under increasing salinity concentrations. We conclude that foliar application of GABA acid at 40 mM can alleviate the adverse effects of salinity on the abovementioned French lavender plant characteristics by improving vegetative growth and root characteristics, as well as diminishing chlorophyll degradation, maintaining high leaf relative water content, increasing proline accumulation and antioxidant activity.
... The activity was stated as the increase in absorbance min −1 g −1 fresh weight. POX activity was recorded for the crude extract according to Hammerschmidt et al. [64], and the changes in absorbance were measured at 470 nm every 3 min. Enzyme activity was recorded as the increase in absorbance (min −1 g −1 fresh weight). ...
Stem rust, caused by Puccinia graminis f.sp. tritici, is one of the most dangerous rust diseases on wheat. Through physiological, biochemical, and molecular analysis, the relationship between the change in resistance of 15 wheat cultivars to stem rust disease and the response of 41 stem rust resistance genes (Sr,s) as well as TTKSK, TTKST, and TTTSK races was explained. Some cultivars and Sr genes, such as Gemmeiza-9, Gemmeiza-11, Sids-13, Sakha-94, Misr-1, Misr-2, Sr31, and Sr38, became susceptible to infection. Other new cultivars include Mir-3 and Sakha-95, and Sr genes 13, 37, 40, GT, and FR*2/SRTT3-SRTT3-SR10 remain resistant. Some resistance genes have been identified in these resistant cultivars: Sr2, Sr13, Sr24, Sr36, and Sr40. Sr31 was not detected in any cultivars. Reactive oxygen species such as hydrogen peroxide and superoxide, enzymes activities (catalase, peroxidase, and polyphenoloxidase), and electrolyte leakage were increased in the highly susceptible cultivars, while they decreased in the resistant ones. Anatomical characteristics such as the thickness of the epidermis, ground tissue, phloem tissue and vascular bundle diameter in the midrib were decreased in susceptible cultivars compared with resistant cultivars. Our results indicated that some races (TTKSK, TTKST, and TTTSK) appeared for the first time in Egypt and many other countries, which broke the resistant cultivars. The wheat rust breeding program must rely on land races and pyramiding genes in order to develop new resistance genes that will survive for a very long time.
... The total phenol was expressed in mg g −1 fresh weight. b) Estimation of oxidative enzyme activity Peroxidase (POX) activity was directly determined according to a typical procedure proposed by Hammerschmidt et al. (1982). Polyphenol oxidase (PPO) activity was determined according to the method described by Malick and Singh (1980). ...
Rust fungi are devastating plant pathogens, and several Puccinia species have exerting substantial financial impacts on global barley cultivation. Fungicides are used on a large scale as an effective method for combating phytopathogenic fungi. The negative environmental impacts of fungicides are steadily escalating on a daily basis. Consequently, researchers are currently exploring alternative approaches to mitigate the use of fungicides, such as the utilization of plant extracts. This method has proven effective due to its incorporation of natural antifungal substances. Among the nine natural elicitors that were tested, the application of plant extracts on barley seedlings resulted in an increase in the incubation and latent periods of Puccinia hordei. These periods are integral components of partial and induced resistance, effectively mitigating the incidence of barley leaf rust disease by over 70% on mature plants. Similarly, the biochemical analyses demonstrated a notable augmentation in all the tested treatments’ overall phenolics and oxidative enzyme activities (peroxidase and polyphenol oxidase). Random amplified polymorphic DNA (SCoT) test serves as a viable approach for assessing the impact of plant extracts and microorganisms on barley plants. The results obtained from this study indicate that the detection of DNA polymorphism through SCoT analysis holds a significant potential powerful tool to evaluate genetic changes compared with untreated plants although some of them tested displayed high similarities at the morphological reaction.
... The APX activity was calculated using the extinction coefficient of 2.8 mM cm -1 and the enzyme activity was reported as m min -1 mg protein -1 . POX activity was determined by following the procedures of Hammerschmidt et al. (1982).The reaction mixture of 0.01 M Phosphate buffer and 2 ml of 0.25% guaiacol was added with 0.1M Hydrogen Peroxide. Increase in absorbance was noted at 420 nm. ...
Using chemical defoliants to remove cotton leaves represents a groundbreaking shift in cotton cultivation. The mechanization of cotton harvest is increasing, but a substantial amount of foliage that remains on the plant even at maturity is the major barrier for mechanical harvest. Properly completing mechanical and manual harvests requires artificial leaf detachment through defoliants. Still there is no proper defoliant concentration, application times and mechanism of action available. Therefore, the present study aimed to find an effective defoliant and application time to enhance mechanical harvest efficiency, along with a clear description of the mechanism of actions in cotton CO17 (Gossypium hirsutum). The field experiment was conducted during the year 2019-20 and used five concentrations of Thidiazuron defoliant (100, 150, 200, 250 and 300ppm) and Ethephon@0.5% (T2) in cotton variety CO17 to study the physiological, biochemical and hormonal responses at 120, 127 and 134 days after sowing. As a result, the concentrations of plant growth hormones, indole-3 acetic acid (4.9 fold), zeatin (32.7%) and gibberellic acid (7 fold) reduced. In contrast, abscisic acid (48.6%), jasmonic acid (34.9%), salicylic acid (2.15 fold) increased in the T7- Thidiazuron + Diuron (300 ppm) treatment followed by T5-Thidiazuron + Diuron (200 ppm). Additionally, the antioxidant enzymes ascorbate peroxidase, peroxidase, catalase, superoxide dismutase, cellulase in leaves, petiole and bolls were decreased due to defoliant T5- Thidiazuron + Diuron (200 ppm) followed by T7-Thidiazuron + Diuron (300 ppm), indicating that the hormone concentration, antioxidative and hydrolytic enzymes are ruled out and forces the defoliation process.
... The reading was taken at 420 nm to a mixture of Pyrogallol (0.05 M) and 100 µl aphid enzyme extract. The enzyme activity was expressed as change in absorbance/ min/g sample [28]. Glutathione-S-transferase (GST) was determined by added 25 µl of the substrate 1-chloro 2,4-dinitrobenzene solution (CDNB) to reaction mixture (1 ml of phosphate buffer, pH 6.5, 100 µl of glutathione (GSH) and 200 µl of aphid extract). ...
Piercing sucking pests are destructive to many strategic crops all over the world. Botanical pesticides can be used to control these pests. A new withanolide derivative 3 named sominone A ((20 R ,22 R )-1 α ,3 β ,20,27-tetrahydroxywitha-5,24-dienolide) was isolated from the alkaloid fraction of the whole plant of Withania somnifera . In addition, there are three known compounds named withasomine 1 , methyl isoferulate 2 , and coagulin Q 4 were also isolated. The structures of isolated compounds were identified using different spectroscopic methods such as 1D, 2D NMR, and HRESIMS spectroscopy. The alkaloid fraction and the four isolated compounds were tested for their pesticidal activity against four piercing sucking pests ( Aphis craccivora Koch, Bemisia tabaci Gennadius, Nezara viridula Linnaeus, and Tetranychus urticae Koch) that attack many strategic crops under laboratory conditions, along with azadirachtin (Okios 3.2% EC) as a positive control. The results showed that the alkaloid compound (withasomine 1 ) was the most toxic to A. craccivora , B. tabaci , N. viridula, and T. urticae, with LC 50 values of 15.44, 36.61, 85.11, and 128.28 ppm, respectively, compared with the control. Withanolide compounds had moderate effects on all tested pests. Biochemical parameters of six enzymes; α -esterase, β -esterase, chitinase, acetylcholinesterase, glutathione- S -transferase, and peroxidase of A. craccivora were estimated at the LC 50 value of the most potent compound, withasomine 1 and the values were 38.83, 72.86, 31.45, 506.4, 2.62, and 251.0, respectively. The results demonstrated that all enzymes activity levels were increased compared with the control except a remarkable inhibition in AChE enzyme level was observed compared with control. Therefore, the alkaloid fraction of W. somnifera is a promising extract that contains many active compounds that can be used as a natural pesticide against many harmful pests in agriculture crops.
Graphical Abstract
... was calorimetrically determined and expressed as μmol tetraguaiacol g -1 FW min -1 (Hammerschmidt et al., 1982). Catalase enzyme (CAT, EC 1.11.1.6) ...
The effective role of different auxins on adventitious roots (Ars) formation of stem cuttings relies on several factors including type of auxins, concentrations and the intermixing materials. In this study, bee honey (BH) was evaluated as a cofactor for maximizing the promoting effect of indole-3-butyric acid (IBA) for better survival of propagated hard-to-root ornamental plants. To improve Ars morphogenesis of Cupressus macrocarpa L. var. Goldcrest, a greenhouse experiment was conducted to evaluate the efficacy of exogenous application of IBA intermixed with BH in comparison with talcum powder (TP) on morphological, biochemical, histoanatomical, and ultrastructural responses. Results indicated that 500 mg kg-1 IBA intermixed with BH (T5) was the superior treatment for improving rooting percentage and root growth measurements. Exogenous application of T5 led to maximize activities of polyphenol oxidase and catalase enzymes as well as total phenols content; however, it caused a sharp decline in peroxidase enzyme activity as compared with untreated cuttings. Additionally, this treatment decreased amounts of gibberellin, benzyl adenine, kinetin and abscisic acid, while the endogenous content of indole-3-acetic acid increased. Histoanatomical observations of stem cuttings treated with T5 showed four prominent phases for adventitious root formation including: induction, initiation of meristemoids, root primordial formation and Ar elongation at 0–6th, 6-12th, 12-18th and 18-30th day after planting (dap). The Ar primordia evolved via two different developmental pathways: (i) indirect genesis (i.e., callus tissues) and (ii) direct genesis (e.g., cells in the inner bark, medullary rays and surrounding tissues). The time-course histoanatomical data of this study provide insights regarding the potential utilization of IBA intermixed with BH to improve Ar formation of several hard-to-root ornamentals
... The activity of superoxide dismutase (SOD) was measured using the nitrogen blue tetrazolium photochemical reduction method [33]. The peroxidase (POD) activity was measured using the guaiacol colorimetric method [34]. The activity of catalase (CAT) was determined via the UV absorption method [35]. ...
Salt stress is a key environmental factor that has adverse effects on plant growth and development. High salinity induces a series of structural and functional changes in the morphological and anatomical features. The physiological and biochemical changes in K. foliatum in response to salt stress in natural environments are still unclear. Based on this, this study compared and analyzed the differences in the physiological and biochemical indicators between the leaf and root tissues in high-salt and low-salt habitats, selecting K. foliatum as the research object. The results showed that the chlorophyll contents in the leaves of K. foliatum decreased in the high-salt habitat, while the thicknesses of the upper and lower epidermises, as well as the thicknesses of the palisade tissue, significantly increased. The high-salt environment led to decreases in the N and P contents in the leaves and root tissues of K. foliatum, resulting in changes in the stoichiometric ratio of elements. The concentrations of C, N, and P in the roots of K. foliatum were lower than those in the leaves. The accumulation of Na+ in the K. foliatum roots was greater than that in the leaves, and the roots could promote the transport of sodium ions to the leaves. The contents of starch and soluble sugar in the leaves showed higher proportions in the high-salt habitat than in the low-salt habitat, while the changes in the roots and leaves were the opposite. As the salt content increased, the proline contents in the leaves and roots of K. foliatum significantly increased, and the proline contents in the roots of K. foliatum were lower than those in the leaves. The leaves and roots exhibited higher levels of peroxidase and superoxide enzymes in the high-salinity habitat than in the low-salinity habitat. The superoxide dismutase (SOD) activity of the K. foliatum leaves and catalase (CAT) activity of the roots were the “central traits” in the high-salt habitat. In the low-salt habitat, the leaf malondialdehyde (MDA) and root C/N were the central traits of the leaves and roots, indicating that K. foliatum adapts to changes in salt environments in different ways.
... The quantification of the POD enzyme activity was determined according to the methodology described by Hammerschmidt, Nuckles, and Kuć (1982), with modifications. An aliquot of 100 µL of the crude extract from peel and 300 µL of the flesh was added to 2.9 and 2.7 mL of the reaction buffer, respectively, composed of 5 mL of 50 mM potassium phosphate buffer (pH 6.0, Vetec, Brazil), 12.5 µL of pure guaiacol (Vetec, Brazil), and 16.3 µL of pure H 2 O 2 (Vetec, Brazil). ...
This study aimed to evaluate the effect of the summer pruning time in 'Fuji' apple trees on the quality of fruit at harvest and after storage in controlled atmosphere with extremely low O2 (CA-ELO) (0.5 kPa O2). The treatments evaluated were summer pruning in December, January, and February, in addition to a control treatment (without summer pruning). The experiment was carried out in the 2018/2019 and 2019/2020 growing seasons. The fruit were evaluated at harvest and after eight months of CA-ELO (0.5 kPa O2 + <0.5 kPa CO2/1.5 ± 0.2°C/92 ± 2% RH) storage, at chamber opening, and after 7 days of shelf-life at 23 ± 3°C and 60 ± 5% RH. The quality of the fruit was evaluated through of soluble solids, flesh firmness, titratable acidity, fruit color, and physiological disorder incidence (sunburn and flesh browning), in addition to enzymatic activity and concentration of functional compounds. There was no significant effect of the summer pruning time on fruit flesh firmness, soluble solids, titratable acidity, and rot incidence after storage under CA-ELO plus 7 days of shelf life. Summer pruning in February resulted in fruit with higher peel red color development, which in general contains a higher concentration of functional compounds at harvest (total phenolic compounds and total antioxidant activity), and lower flesh browning incidence in 'Fuji' apples stored under CA-ELO. The nitrogen (N) concentration and nitrogen/calcium ratio (N/Ca) in the second growing season were lower in fruit from plants pruned in February, compared to no summer pruning or earlier pruning. The superoxide dismutase and peroxidase enzyme activity were lower in fruit from treatments with summer pruning in January and February, whereas the polyphenol oxidase enzyme activity was lower when summer pruning was conducted in February.
... Peroxidase (PO) assay: PO (EC 1.11.1.7) activity was assayed by the method of Hammerschmidt et al. [18], with slight modification. Leaf samples (0.1 g) were homogenized separately in 2 ml of 0.1 mol l -1 phosphate buffer (pH 7.0), at 4 0 C, centrifuged at 16000 x g at 4 0 C for 15 min and the supernatant was used as enzyme source. ...
Tomato (Solanum lycopersicum) is a widely cultivated and versatile fruit. Tomato production faces various constraints, both biotic and abiotic stresses. Fusarium wilt, caused by the soil-borne fungus Fusarium oxysporum f. sp. lycopersici, is a devastating disease that affects tomato plants worldwide, causing significant economic losses in tomato cultivation. Inthis study the potential use of biofortified vermicompost for wilt management was investigated. The biological control agents viz. Trichoderma harzianum, Pseudomonas fluorescens and Bacillus subtilis were used to fortified the vermicpompost. The study monitored various antioxidants, plant growth indicators, and disease rates across designated treatments at different intervals. The findings revealed substantial differences: tomato plants treated with biofortified vermicompost showed notable reductions in disease occurrence, improved growth, increased yields, and heightened antioxidant activity Original Research Article Bisen et al.; Int. 736 compared to the control. Among these treatments, the most remarkable outcomes were observed in plants treated with T. harzianum fortified vermicompost, exhibiting the highest recorded values across the parameters studied. Data revealed that the Tomato plants treated with vermicompost fortified with Trichoderma showed maximum root length (14.95 cm) after 15 days of sowing followed by T-2 (11.25 cm) and T-3 (9.85 cm). Maximum dry weight was observed in plants treated with vermicompost fortified with Trichoderma. Maximum PAL, PO and PPO activity was recorded in leaves from plant grown in vermicompost fortified with T. harzianum (T1) at 48 h followed by T2, T3 and T4. The findings revealed tomato plants treated with biofortified vermicompost showed notable reductions in disease occurrence, improved growth, increased yields, and higher accumulation of defense enzyme activity compared to the control.
... Ascorbate peroxidase (APX) activity was measured following the procedures of Nakano and Asada (1981) by observing the rate of ascorbate oxidation at 290 nm (molar extinction coefficient 2.8 mM − 1 cm − 1 ) and the values were expressed as μmol min − 1 mg -1 Fw. Peroxidase (POD) activity was quantified according to Hammerschmidt et al. (1982) by recording the rate of guaiacol oxidation at 470 nm (molar extinction coefficient 26.6 mM − 1 cm − 1 ) and the values were expressed as μmol min − 1 mg -1 Fw. Reaction mixture volume was 3 mL for all the enzymatic assay and measurements were taken at room temperature (25 ± 1 • C). ...
Sustainably increasing rice (Oryza sativa L.) becomes more challenging due to environmental stresses. High temperature stress resulting from global warming impact of climate change is highly damaging as it can cause growth and yield reduction of rice via cellular and physio-biochemical impairments. Application of either salicylic acid or chitosan can possibly increase plant's tolerance to different abiotic stresses; however, their combined mitigation effects remained inadequately explored. Thus, the objective of the current study was to evaluate the mitigation potential of combined salicylic acid and chitosan against high temperature stress of rice. The experiment was conducted in a factorial combination of two temperature regimes (optimum temperature [control] and high temperature); two salicylic acid levels (−SA: 0 mg L−1 and +SA: 140 mg L−1); and two chitosan levels (−Ch: 0 mg L−1, +Ch: 100 mg L−1) following a completely randomized design. High temperature impaired rice growth and productivity by negatively influencing all tested parameters; however, salicylic acid and chitosan could significantly mitigate those impairments. The mitigation on growth and yield contributing parameters was recorded at best 11 %, 21 %, 12 %, 75 %, 61 %, 46 %, 27 %, and 43 % for plant height, leaf area, shoot dry matter, pollen viability, effective tiller percentage, filled grain percentage, 1000-grain weight, and grain yield respectively. Highest alleviation in physio-biochemical parameters was also found at best 35 %, 68 %, and 67 % for leaf greenness, net photosynthetic rate, and stomatal conductance respectively with 28 % and 60 % respective increase in transpiration rate and proline concentration. Superoxide dismutase, catalase, ascorbate peroxidase and peroxidase activity were also boosted as high as 1.6-folds, 1.4-folds, 1.9-folds, and 2.6-folds respectively with subsequent reduction of 32 % lipid peroxidation and 34 % hydrogen peroxide concentration. For all tested parameters, the best positive effects were observed under combined salicylic acid and chitosan treatment. Individually, salicylic acid was found more effective than chitosan; however, their combined application resulted in significantly better alleviation responses over their individual application for most studied parameters. Our findings would contribute in present understanding of high temperature stress and would also help in strategizing better-suited management practices toward sustainable rice productivity.
... Peroxidase activity was evaluated using the method described in (Hammerschmidt et al., 1982). Catalase activity assay: ...
Neonicotinoids, which have a wide range of applications, are systemic insecticides that efficiently control several sucking pests. Recently, thiamethoxam (THIA) has become one of the popular pest control agents. In vivo study, the toxicity of THIA was evaluated against a laboratory strain of cowpea aphid (Aphis craccivora Koch.) using the leaf dipping method for 24 and 48 hrs of exposure. In silico study, THIA was docked to acetylcholine binding protein (AChBP) to explain their binding mode of interaction. THIA exhibited good toxicity against adult aphids with LC50 of 2.44 ppm at 24 hrs post-treatment, which greatly decreased to 0.75 ppm at 48 hrs post-treatment. THIA showed better binding interaction with AChBP than the co-crystalized ligand (imidacloprid) and good alignment in the active site. THIA indicated different variations in the activities of tested enzymes. Where, aphids treated with LC50 of THIA increased the biochemical activities of acetylcholinesterase, antioxidant enzymes and peroxidases while decreasing the activity of alpha esterase, carboxylesterase (CarE), glutathione S-transferase and catalase. Therefore, this compound is efficient against sap-sucking pests with good irreversible and specific binding interaction with nicotinic acetylcholine receptor (nAChR) and, consequently, low mammalian toxicity. So, THIA is considered a favourable agent for the management of insect pests.
... We used the method of Hammerschmidt et al. [1982] to assay POD activity. 490 μl of 225 mM hydrogen peroxide solution and 490 μl of 45 mM guaiacol solution were mixed, and 20 μl of plant sample extract was added. ...
An experiment was conducted in a completely randomized design (CRD) with factorial arrangement with three treatments of salinity (0 or check, 150, and 300 mM), and five bacterial elicitors treatments (fungal consortium (bioactive) (BFC), fungal elicitor at 1,000 ppm concentration (EL1), fungal elicitor at 2,000 ppm concentration (EL2), bacteria (BS) (Bacillus safensis), and bacteria (BP) (Bacillus pumilus)) in the Horticultural Science Laboratory to evaluate the effect of biological elicitors, including fungi and bacteria, on resistance to salinity stress in the date palms. The results showed that the lowest hydrogen peroxide content (278 µmol/g) was found in the elicitor of B. safensis at the zero salinity level. Catalase enzyme activity was higher in the treatments of fungal elicitor at 2,000 ppm concentration and the zero salinity level, B. safensis at the 150 mM salinity level, and fungal consortium at the 300 mM salinity level. The hydrogen peroxide content in the plant decreased as the activity of PAL and PPO enzymes increased. Applying an elicitor may reduce the effects of salinity stress in the date palm, but the stress level could determine the impact of each elicitor.
... POX activity was recorded through the conversion of tetra-guaiacol and guaiacol at 470 nm in a UV/Vis spectrometer (Labomed 2602, PerkinElmer, Waltham, MA, USA) following the method described by Hammerschmidt et al. [40] and modified by Khoa et al. [10]. It was expressed as changes in absorbance at 470 nm per min per mg protein of fresh leaf tissue. ...
Bacterial leaf blight (Xanthomonas oryzae pv. oryzae) is a significant rice disease. Aqueous crude extracts of Kalanchoe pinnata were shown to induce rice resistance against the disease. This study aims at testing the disease-reducing effects of K. pinnata leaf extracts using the liquid–liquid extraction method with three different solvents (dichloromethane, methanol, and water). This serves as a basis to select appropriate extracts for effective disease control. Three concentrations (1, 1.5, and 2%) of each extract were tested using seed soaking. The extracts did not show adverse effects on seed germination and seedling growth. Methanol extracts showed significantly different effects compared to those of the untreated control. The involvement of induced resistance in the disease reduction was shown through activities of the four defense-related and antioxidant enzymes, i.e., peroxidase (POX), catalase (CAT), polyphenol oxidase (PPO), and phenylalanine ammonia lyase (PAL). Using 1% methanol extract, activities of POX and CAT involved in hydrogen peroxide production in rice tissues increased 1–4 days after pathogen inoculation (DAI) and remained at high levels until 6 DAI. Activities of PPO and PAL involved in resistance signaling pathways significantly increased after pathogen inoculation. Activities of the four enzymes generally increased after pathogen inoculation and reached higher levels with extract applications.
... PO was assayed by estimating the absorbance change at 470 nm of guaiacol oxidation in existence of H 2 O 2 and the enzyme sample every 30-s intervals. The change in absorbance at 470 nm/min/mg protein was used to measure peroxidase activity (Hammerschmidt et al. 1982). The protein content was calculated as described by Bradford (1976). ...
Background
Leveillula taurica is an obligate pathogen that causes powdery mildew on chili pepper ( Capsicum annuum L.) which is considered one of the most serious diseases for the crop.
Results
Leveillula taurica was isolated from infected pepper plants in Assiut Governorate, Egypt. Pathogenicity test was performed, and it was found that the pathogen can cause the symptoms of powdery mildew on the pepper plant. Under greenhouse conditions, treatment with Bacillus thuringiensis MW740161.1 , Pseudomonas fluorescens, and Bacillus subtilis cultures resulted in a significant reduction in conidial germination of the pathogen (69.07, 29.55, and 19.58%, respectively). Spraying chili pepper plants with the microorganisms effectively reduced the powdery mildew's disease severity. Also, treatment with the bacterial strains resulted in a significant ( P 0.05%) increase in the yield of chili pepper. Based on the findings, it appears that the use of B. thuringiensis, as foliar spraying, significantly induced resistance of chili pepper plants against L. taurica and stimulated many biochemical functions in the plant. Also, it increased the crop yield compared to all other treatments.
Conclusions
This study recommends B. thuringiensis as a viable alternative to harmful pesticides, and it is feasible to formulate an appropriate fungicide for the sustainable green production of chili peppers. The B. thuringiensis can increase the resistance of chili pepper plant to L. taurica the causal pathogen of powdery mildew.
... Using Malik and Singh's method [22], the activity of polyphenol oxidase (PPO) was measured. The methods of Hammerschmidt et al. [23] were used to measure the peroxidase (POX) activity directly. ...
Eight wheat cultivars, Sakha-94, Giza-171, Sids-1, Sids-12, Sids-13, Shandweel-1, Misr-1, and Misr-2, were evaluated for leaf rust at the seedling and adult stages in the 2021 and 2022 seasons. Biochemical, histological, and genetic analyses were performed to determine the link between cultivars that were either sensitive or resistant to the disease. Misr-2 and Giza-171 cultivars had the highest levels of resistance to leaf rust races in 2021 (LTCGT, STSJT, and TTTST) and 2022 (MBGJT, TTTKS, and TTTTT) at the seedling stage. However, at the adult stage, Sakha-94, Giza-171, Misr-1, and Misr-2 cultivars had the highest levels of resistance; consequently, they had the lowest final disease severity and the lowest values of AUDPC. The correlation between the seedling reaction and adult reaction was non-significant, with values of 0.4401 and 0.4793 in the 2021 and 2022 seasons, respectively. Throughout the biochemical, histological, and genetic analyses, it was observed that catalase, peroxidase, and polyphenol oxidase activities significantly increased in the resistant cultivars. The discoloration of superoxide (O2-) and hydrogen peroxide (H2O2) significantly decreased in resistant and moderately resistant wheat cultivars (Sakha-94, Giza-171, Misr-1, and Misr-2); higher hydrogen peroxide (H2O2) and superoxide (O2-) levels were recorded for the susceptible cultivars compared to the resistant cultivars. Molecular markers proved that the Lr50 gene was detected in the resistant cultivars. Puccinia triticina infections negatively affected most histological characteristics of flag leaves, especially in susceptible cultivars. The thickness of the blade (µ), the thickness of the upper and lower epidermis (UE and LE), the thickness of mesophyll tissue (MT), and bundle length and width in the midrib were decreased in susceptible cultivars such as Sids-1, Sids-13, and Shandwel-1 compared with resistant cultivars.
... Then, 0.5 ml of supernatant, 1.5 ml of 0.05 M pyrogallol, and 0.5 ml of 1 % H 2 O 2 made up the reaction mixture. The final reaction mixture was incubated at 25 ± 2 • C with the absorbance measured at 420 nm at 30 s intervals for 3 min and the peroxidase activity was represented as a change in O.D. min − 1 g − 1 fresh weight (FW) [64]. ...
The present study was carried out in a pot experiment to examine the bioefficacy of three biocontrol agents, viz., Trichoderma viride, Bacillus subtilis, and Pseudomonas fluorescens, either alone or in consortium, on plant growth promotion and activation of defense responses in potato against the early blight pathogen Alternaria solani. The results demonstrate significant enhancement in growth parameters in plants bioprimed with the triple-microbe consortium compared to other treatments. In potato, the disease incidence percentage was significantly reduced in plants treated with the triple-microbe consortium compared to untreated control plants challenged with A. solani. Potato tubers treated with the consortium and challenged with pathogen showed significant activation of defense-related enzymes such as peroxidase (PO) at 96 h after pathogen inoculation (hapi) while, both polyphenol oxidase (PPO), and phenylalanine ammonia-lyase (PAL) at 72 hapi, compared to the individual and dual microbial consortia-treated plants. The expression of antioxidant enzymes like superoxide dismutase (SOD) and catalase (CAT) and the accumulation of pathogenesis-related proteins such as chitinase and β-1,3-glucanase were observed to be highest at 72 hapi in the triple microbe consortium as compared to other treatments. HPLC analysis revealed significant induction in polyphenolic compounds in triple-consortium bioprimed plants compared to the control at 72 hapi. Histochemical analysis of hydrogen peroxide (H2O2) clearly showed maximum accumulation of H2O2 in pathogen-inoculated control plants, while the lowest was observed in triple-microbe consortium at 72 hapi. The findings of this study suggest that biopriming with a microbial consortium improved plant growth and triggered defense responses against A. solani through the induction of systemic resistance via modulation of the phenylpropanoid pathway and antioxidative network.
The present studies were undertaken to investigate the effect of bioprotectant, plant based chemical like Salicylic acid and silicon based nutrient Potassium silicate against the anthracnose or ripe fruit rot of chilli (Capsicum annuum L.) incited by Colletotrichum capsici (Sydow.) Butler and Bisby in chilli var. K2. The chilli anthracnose disease susceptible variety Kovilpatti-2 (K2) grown in pots and field trial were used for the study. The plants were given artificial inoculation by spraying the spore suspensions after pinpricking the fruits with adequate spore load at 90-days after transplanting for fruit rot incidence assessment. The crop was maintained in a poly house with frequent spraying of water to provide adequate moisture and relative humidity to enable successful infection by the pathogen. Three replications for each treatment and a control were maintained. The fungicide mancozeb @ 0.25 per cent was used for comparison and the standard agronomic practices as recommended by the State Agricultural Department were followed. The plant activator and silicon-based nutrient were sprayed as individual as well as combined approach manner. Seed treatment with Pseudomonas fluorescens @ 10 g/kg of seeds in all the treatments except comparison fungicide and control treatments. Among the various treatments, seed treatment with Bio protectant, foliar application of Salicylic acid @ 50 ppm on 40 days after transplanting (40 DAT) and foliar application of Potassium silicate @ 3 % on 60 DAT recorded the minimum disease incidence and increased fruit length, fruit weight, fruit per plant, branches per plant, plant height and germination percentage when compared to control and Comparison fungicide Mancozeb. The activity of plant defense enzymes like Peroxidase, polyphenol oxidase and Phenylalanine ammonia lyase increased up to 5th day of sampling in plants treated with Bio-protectant, resistance inducing chemical along with potassium silicate and challenged inoculated with the test pathogen. Also, the same treatment significantly decreased the disease severity and increased the growth and yield parameters when compared to control and comparison fungicide under the field trials.
The greenhouse effect caused by global warming was becoming more and more obvious, resulting in increased frequency of high temperature and high humidity, which significantly affected maize productivity. However, it was poorly understood how the interactions of high temperature and high humidity affected leaf senescence, photosynthetic performance and yield of summer maize. Three stress treatments including (a) high temperature stress (T), (b) waterlogging stress (W) and (c) complex stress (T‐W) were set at the third leaf stage (V3), the sixth leaf stage (V6) and the tasselling stage (VT) in 2019–2020 to explore the influence mechanism of complex stress. Each stress treatment period lasted 6 days. Non‐stressed plants served as control. Yield, antioxidant enzyme activity, photosynthetic characteristics, and dry matter accumulation were determined. Our study found that the activity of antioxidant enzymes was significantly decreased, while malonyldialdehyde (MDA) accumulation was increased under each stress treatment. As a result, the photosynthetic characteristics were impaired, manifested in a significant decrease in net photosynthetic rate ( P n), enzyme activities of phosphoenolpyruvate carboxylase (PEPCase) and ribulose diphosphate carboxylase (RUBPCase). The decrease in photosynthetic intensity affected by each stress treatment led to a significant decrease in total dry matter accumulation and grain yield. The most significant effects of waterlogging and combined stresses on yield occurred at the V3 stage, followed by the V6 and VT stages. However, the most significant effects of high temperature occurred at the VT stage, followed by the V6 and V3 stages. Moreover, the compound stress exacerbated damage to leaf senescence and photosynthetic properties of summer maize compared to the single stress of high temperature or waterlogging.
This study evaluated the impact of Zinc (Zn) doses on biochemical and growth attributes in tomato plants (Solanum lycopersicum L). The plants were cultivated under greenhouse conditions in two agricultural soils Inceptisol and Oxisol. The following doses of Zn were evaluated: Inceptisol: control, 20, 40 and 60 mg kg− 1; Oxisol: control, 40, 80 and 120 mg kg− 1. Mineral contents in aerial parts of plants, gas exchange, SPAD index, superoxide dismutase (SOD) and peroxidase (POD) activity, peroxide content of hydrogen, lipid peroxidation, root growth parameters and shoot and root dry mass production were evaluated. Plants accumulated dose-dependent Zn in their shoot tissues in both soils. This increase in Zn (60 mg Kg− 1) in Inceptisol and (120 mg Kg− 1) in Oxisol inhibited of dry mass production (-19.3% in Inceptisol and − 15.0% in Oxisol), photosynthesis (-17.0% in Inceptisol and − 18.8% in Oxisol), and root growth (-52.8% in Inceptisol and − 39.0% in Oxisol).This increase in Zn (60 mg Kg− 1) in the tissues stimulated an increase in the activity of SOD (40.1%) and POD (102.9%) enzymes in plants grown in Inceptisol. The 20 mg kg− 1 (Inceptisol) and 40 mg kg− 1 (Oxisol) treatments were not efficient in promoting plant growth and development. Thus, this study indicated that the application of Zn, for nutritional purposes, must be carefully evaluated since its effects are variable, without benefit in doses considered sufficient and possibly toxic in high doses in tomato plants.
Early blight (EB), caused by Alternaria solani, is a serious problem in tomato production. Plant growth-promoting rhizobacteria promote plant growth and inhibit plant disease. The present study explored the bio-efficacy of synergistic effect of rhizobacterial isolates and ginger powder extract (GPE) against tomato EB disease, singly and in combination. Six fungal isolates from symptomatic tomato plants were identified as A. solani on the basis of morphological features i.e., horizontal septation (6.96 to 7.93 μm), vertical septation (1.50 to 2.22 μm), conidia length (174.2 to 187.6 μm), conidial width (14.09 to 16.52 μm), beak length (93.06 to 102.26 μm), and sporulation. Five of the twenty-three bacterial isolates recovered from tomato rhizosphere soil were nonpathogenic to tomato seedlings and were compatible with each other and with GPE. Out of five isolates tested individually, three isolates (St-149D, Hyd-13Z, and Gb-T23) showed maximum inhibition (56.3%, 48.3%, and 42.0% respectively) against mycelial growth of A. solani. Among combinations, St-149D + GPE had the highest mycelial growth inhibition (76.9%) over the untreated control. Bacterial strains molecularly characterized as Pseudomonas putida, Bacillus subtilis, and Bacillus cereus and were further tested in pot trials through seed bacterization for disease control. Seeds treated with bacterial consortia + GPE had the highest disease suppression percentage (78.1%), followed by St-149D + GPE (72.2%) and Hyd-13Z + GPE (67.5%). Maximum seed germination was obtained in the bacterial consortia + GPE (95.0 ± 2.04) followed by St-149D + GPE (92.5 ± 1.44) and Hyd-13Z + GPE (90.0 ± 2.04) over control (73.8 ± 2.39) and chemical control as standard treatment (90.0 ± 2). Ginger powder extracts also induce the activation of defence-related enzymes (TPC, PO, PPO, PAL, and CAT) activity in tomato plants. These were highly significant in the testing bacterial inoculants against A. solani infection in tomato crops.
Tomato (Solanum lycopersicum) is a globally significant crop, but its cultivation is challenged by the devastating Early Blight disease caused by Alternaria solani, leading to substantial yield losses. Silver nanoparticles (AgNPs) have emerged as potential antifungal agents, garnering increasing attention. In this study, we investigated the impact of biogenic AgNPs on tomato plant defense mechanisms during a three-way interaction with plant pathogens and nanoparticles. Additionally, the study explored the integration of biochemical markers to assess plant response. His-tochemical analyses confirmed the presence of oxidative stress markers (H 2 O 2 and O À 2), as well as callose and lignin deposition, supporting the involvement of defensive responses in this study. Metabolic profiling revealed that tomato plants exposed to 20 ppm AgNPs exhibited maximal accumulation levels of various secondary metabolites compared to the control group. Remarkably, the concurrent application of AgNPs and plants resulted in enhanced plant resistance against biotic stress, as evidenced by reduced stress parameters and stress enzyme activity. The anti-oxidant enzymes (PO, SOD, CAT, LPX) exhibited significant variations among treatments, emphasizing the influence of AgNPs on maintaining reactive oxygen species (ROS) homeostasis in plant cells. These findings highlight the potential of nanotechnology-based approaches in bolstering food supply and promoting sustainable agriculture. Our study underscores the significance of integrating biochemical markers to monitor and assess plant response during the interaction with nanoparticles and pathogens. This integration offers a promising avenue for elucidating the underlying mechanisms of plant defense and optimizing agricultural practices. In conclusion, our research elucidates the potential of silver nanoparticles in augmenting plant resistance against Early Blight disease in tomato, ultimately contributing to sustainable agriculture. The incorporation of biochemical markers further advances our understanding of the intricate interplay between nanoparticles, plant pathogens, and plant defense mechanisms.
The efficacy of selenium (Se) to ameliorate salinity stress in Brassica rapa was elucidated using an in-vitro and in-silico hybrid approach. Selenium was applied as a seed priming agent on the seeds grown in salt-spiked soils. The priming treatment facilitated all the growth indicators and physiological parameters, including chlorophyll synthesis, sugar contents, gas exchange attributes, etc. The advantageous effects of Se were accredited to the alleviation of salinity stress through reducing the malondialdehyde (MDA), proline, electrolyte leakage, and hydrogen peroxide (H 2 O 2) level. Similarly, modulations in the expression of genes encoding antioxidative enzymes enhanced reactive oxygen species (ROS) scavenging capacity along with a decrease in sodium (Na +) ions, reciprocally enhancing potassium (K +) ions and resulting in a higher K + /Na + ratio. Additionally, based on in silico studies, a significant difference in the surface overlap of the stress-responsive proteins, including DREB, SOS3, and STXBP1 of B. rapa, was observed, indicating the involvement of Se in the foiling interaction of NaCl with the enzymes. In the case of the CAT macromolecule, ligands NaCl exhibited a-1.9-fold lower docking score as compared to sodium selenite-4.9-fold, indicating a more overlapped interactive surface than sodium chloride. The binding energies analysis recorded-3.3 kcal/mol of binding energy for the best pose of sodium selenite in the case of DREB, while it was-3.5 and-3.5 kcal.mol-1 for SOS3 and 1 STXBP1, respectively. Ligand analysis revealed a frequent existence of hydrogen bonds besides the hydrophobic interactions, salt bridges, and pi-pi interactions representing high structural and functional stability. Results of the current study unveiled an in-vitro and in-silico hybrid bioinformatics system to unveil the biochemical, physiological and molecular phenomenon behind selenium-driven salt resilience in B. rapa.
An innovative tissue culture mediated incorporation of metabolite-based biomolecule (Bio-immune) at in vitro stage itself in banana cv. Grand Naine was developed and validated for the production of Fusarium oxysporum f.sp. cubense TR4 tolerant plantlets. The novel bio-immune formulation developed by us, exhibited a significant antifungal potency against Foc TR4 with a high percent inhibition (100%) at a 2.5% concentration of bio-immune on the 5 th , 7 th , and 9 th DAI. Bio-immune integrated during in vitro shoot proliferation stage in banana cv. Grand Naine recorded significant enhancement in the growth of roots and shoots. Bio-immune (0.5%) fortified media produced 12.67 shoots per clump whereas control registered only 9.67 shoots per clump. Similarly, maximum root numbers (7.67) were observed in bio-immune plants which were significantly higher over control (5.0). The bio-immunized banana transplants recorded a higher survival rate (97.57%) during acclimatization as compared to the control (94.53%). Furthermore, evaluation of the bio-immunized plants in pot experiments revealed that unimmunized plants treated with Foc TR4 (TF) exhibited mortality between 60 and 90 days. On the 90th day after planting, a high mean disease severity index (DSI) of 3.45 was observed with unimmunized plantlets while the bio-immunized plants (TFBI) and ICAR-FUSICONT treated plants (TFTR) showed substantially reduced DSI (0.20 and 1.00) compared to Foc TR4 treated control (TF). Significant increases in polyphenol oxidase (PPO), peroxidase (POD), β-1,3-glucanase, phenylalanine ammonia-lyase (PAL), chitinase activities, and enhanced phenol contents were recorded in bio-immunized plants compared to unimmunized plants. Field experiments at two different locations in Bihar, India revealed that bunch weight, no. of hands/bunch, and no. of fingers/hand of bio-immune treated plants were significantly higher compared to the control.
Okra, Abelmoschus esculentus (L.) Moench, being highly susceptible to yellow vein mosaic virus (YVMV) disease warrants its genetic improvement for resistance. Applied mutagenesis programme using two optimum doses of gamma radiation, namely, 350 Gy and 450 Gy radiation, was administered for the variety Pusa Sawani rated as excellent for fruit quality but highly susceptible to YVMV disease. Two selected putative mutant families, namely, 350//10///3‐9////28 and 450//66///2‐4////39, isolated in the M 5 generation with slightly different plant morphology as compared to the parental genotype, Pusa Sawani, showed consistent resistance against YVMV disease. Upon evaluation in the M 6 generation, eight morphological characteristics and five quantitative characteristics differed significantly among the mutants and Pusa Sawani. Proximate compositions and enzyme activity in leaf were significantly higher in the two YVMV‐resistant mutants. Disease screening under artificial inoculation in the insect proof cages confirmed YVMV resistance in these mutants. DNA fingerprinting further validated the alterations occurred in these two isolated mutants compared to the parental genotype. These mutants deserve due attention towards the development of YVMV‐resistant variety.
Drought stress is one of the major abiotic factors that cause a significant decline in the crop’s productivity. It can
disturb photosynthesis by inducing oxidative stress by producing reactive oxygen species. Recently, the use of
quantum has gained the attention of scientists due to its potential positive impacts on plants under stress conditions.
That’s
why a current study was conducted to explore the impact of Zn-quantum dot biochar (QDB) on
rapeseed growth under drought stress. There were four levels of QDB, i.e., control (no QDB), 0.2 %, 0.4 %, and
0.8 %, applied on a w/w basis in soil under normal irrigation and drought stress. Results showed that 0.8 %QDB
performed significantly better in improving seedling’s emergence, plant height, number of branches/plants,
number of pods/plants, pod length, seed weight/plant, 1000 seeds weight, and total biomass of rapeseed under
normal irrigation and drought stress. At 0.2 %, 0.4 %, and 0.8 % QDB levels, the photosynthetic rate was 9.19 %,
11.78 %, and 13.46 % higher than the control under drought stress. Compared to the control, the transpiration
rate increased by 61.40 % with 0.2 % QDB, 123.46 % with 0.4 % QDB, and 199.71 % with 0.8 % QDB. The
percentage increase in stomatal conductance ranged from 44 % for 0.2 % QDB to 129 % for 0.8 % QDB under
drought stress. In conclusion, 0.8 %QDB can potentially reduce drought stress and improve the leaf water
contents and nutrient uptake in rapeseed.
Bakanae, caused by a fungal pathogen Fusarium fujikuroi is a major burden in rice cultivation. Management of this disease is crucial as it has the risk of being associated with the seed while exporting. Regular application of fungicides promotes the development of resistance to the molecule, and the lack of newer compounds paved the way for alternative management strategies. Salicylic acid (SA) and potassium silicate (PS) have gained momentum recently for their beneficial effects in promoting plant growth and controlling disease. Potassium silicate and salicylic acid are known to play a key role in enhancing plant defense. The present study investigates the individual and combined effect of PS and SA seed priming for plant growth and defense responses against Fusarium fujikuroi. The seed priming combined with SA (100 mg/L) and PS (1.0%) effectively controlled the bakanae disease incidence. In addition, it was also effective on growth parameters like improved germination, root and shoot length, plant biomass, and seedling vigor. Accumulation of defense enzymes like phenylalanine ammonialyase (PAL), polyphenol oxidase (PPO), Peroxidase (POD), and phenol derivatives was significantly higher in the treated plants. The maximum activity of these defense enzymes was recorded in PS+SA-treated plants at 21 DAS. The plant treated with SA-100 mg/L+ PS-1% showed the best response without any phytotoxic effect. The information gathered in the present study suggests that seed priming of SA-100 mg/L+ PS-1% can promote plant growth and suppress bakanae disease in rice. This research demonstrates how PS and SA can be used to combat the F. fujikuroi in rice by activating key defense enzymes. Additionally, applying these substances to plants stimulates their antioxidant defences, which indirectly prevents the spread of disease. In place of fungicides, the PS and SA treatment options are harmless for the environment and can be used to manage the bakanae disease. Future studies may be initiated to identify potential mechanisms behind the combined effects of SA and PS on plant growth promotion and disease suppression.
It is well known that the total metabolic activity of the cells is under genetic control, simultaneously influenced by environmental factors. The biochemical or physiological responses of host plants to pathogens are therefore not necessarily specific. Increased metabolism of cells is frequently connected with changes of the permeability of the cell walls or with changes in the ultrastructure of the cell organelles (Wheeler and Hanchey, 1968). These processes change the compart-mentalization of substances, often resulting in changes in the concentration of the substrates, cofactors inhibitors and metabolic stimulators which ultimately alter the metabolism of the affected plant.
One of the most prominent common features of vascular plants is their unique capacity to synthesize lignin. This substance is deposited in the cell walls of lignifying tissues, especially the xylem, thus providing rigidity to the otherwise elastic polysaccharide cell walls. Terrestrial plants can thus develop arborescent forms and, consequently, the acquisition of lignin is regarded as one of the essential factors in the evolution of higher plants. Lignin contributes about 20-30% of the dry weight of the woody of trees. This fact, together with the conspicuous predominance of vascular plants, indicates enormous quantities of lignin are produced; indeed, after cellulose, lignin represents the second most abundant natural product.
The resistance to anthracnose in cucumber, induced systemically by a localized infection with tobacco necrosis virus (TNV), resembled that induced by Colletotrichum lagenarium and Pseudomonas lachrymans. Systemic resistance to anthracnose was first detectable at the time when symptoms caused by TNV appeared. Increased resistance to anthracnose in the second leaf was detected when eight necrotic lesions were produced on the first leaf by infection with TNV, and increasing the number of TNV lesions on the first leaf increased anthracnose resistance in the second leaf. C. lagenarium penetrated uninfected leaves of TNV-infected plants less frequently than leaves of uninfected plants. Systemic infection of cucumber with tobacco ringspot virus but not with tomato ringspot virus induced resistance to anthracnose. Localized infection of cucumber cotyledons with tobacco mosaic virus did not induce the resistance of true leaves to anthracnose. The resistance induced by C. lagenarium, P. lachrymans resistance of true leaves to anthracnose. The resistance induced by C. lagenarium, P. lachrymans and TNV appears dependent upon the activation of more than one mechanism. It is unlikely to be unique to the infectious agent but rather is dependent upon a common function of the infectious agents.
Phenylalanine ammonia-lyase (PAL) activity was demonstrated in extracts of acetone powders of bean hypocotyls. Since it was observed that cinnamic acid was produced with or without added l-phenylalanine, the origin of this cinnamic acid was investigated. Assay of boiled extracts indicated that cinnamic acid production, with or without added substrate, was enzymatic, and it was shown dialyzed extracts produced cinnamic acid only with added substrate. It was found that extracts contained phenylalanine at four times the level necessary to account for cinnamic acid production without added substrate, and the loss of phenylalanine during autolysis was stoichiometrically equivalent to the cinnamic acid produced. Cinnamic acid was not released during acid or alkaline treatment of extracts, but ferulic acid was found from the alkali treatments. No other evidence for the existence of bound forms of cinnamic acid was obtained, and we conclude that measurements of cinnamic acid production is a valid method of assay for PAL in extracts of acetone powders of bean hypocotyls.
Microscopic examination of whole mounts and sectioned leaf tissue indicated that penetration of cucumber leaves by Colletotrichum lagenarium was reduced in both resistant and susceptible cultivars when the plant was systematically protected by previous infection with the pathogen. Differences were not observed, however, in the number of appressoria produced on protected or unprotected leaves. The degree of protection was reduced by puncturing or abrading the leaf surface of the susceptible cultivars prior to inoculation, and protection was lost by removing a portion of the leaf's epidermal tissue and inoculating the exposed sites with the fungus. Protection was not effective at leaf sites with the epidermis removed even when low concentrations of inoculum were used. Removal of epidermis did not reduce resistance or protection of a resistant cultivar. The resistance of the cultivars Calypso, Addis and Liberty to anthracnose was not due to a reduction in the formation of appressoria or penetration, but was associated with rapid necrotization of penetrated cells. Infectious C. lagenarium was isolated from lesion-free inoculated areas on leaves of systematically-protected plants up to one week after inoculation.
Infection of the first true leaf of cucumber with either Pseudomonas lachrymans or Colletotrichum lagenarium systemically protected susceptible cultivars against disease caused by subsequent challenge with either pathogen. Sonicated bacterial cells, heat-killed cells, formalin-killed cells and a cell-free culture filtrate did not protect. Suspensions of bacteria swabbed onto leaf one or infiltrated into the leaf consistently induced protection against the fungus. The bacterium protected the plant against fungal inoculum containing 103 to 106 conidia ml−1. Systemic invasion by either challenge pathogen was rarely observed in protected plants. An interval of 72 to 96 h after the inducing inoculation was necessary for protection to be expressed. Protection was still evident 37 days after the initial infection. Pseudomonas pisi, P. phaseolicola and P. angulata also protected plants, but this level of protection was significantly less than that elicited by P. lachrymans. Several other bacteria tested did not elicit protection. Populations of P. lachrymans in disks of the challenged second true leaf of unprotected plants were 103 cells greater, 5 days after challenge, than those in protected plants.
By vacuum infiltration of intercellular spaces of tobacco tissues it is possible to extract substances from cell walls which move freely in the walls. The peroxidases (E.C. 1.11.1.7) contained in these extracts are predominantly isoenzymes of GI (fast migrating anodic group) as was shown by discelektrophoresis of the extracts. As has been demonstrated previously GI is not present in the protoplast; therefore GI is the typical cell wall fraction of tobacco peroxidases. Different tissues of tobacco always differ in the isoenzyme pattern of GI. This pattern also changes during tissue development. We can therefore say that there exists an enzymatic differentiation of plant cell walls during development. As GI is not bound to the walls, it always appears in high amounts in crude extracts of plant material. Therefore GI is always called the soluble cytoplasmic fraction, but our investigations clearly demonstrate that GI is localized in cell walls only. Beside GI there are much smaller amounts of GIII (slow migrating cathodic group) and if present in the tissue GII (slow migrating anodic group) detectable in the infiltration fluids of intracellular spaces. GIII and GII are localized mainly in the protoplast. But they are also bound to the walls, ionically in the case of GIII and covalently in the case of GII.
Purified cell-wall preparations from the epicotyl of etiolated Pisum sativum contain covalently bound peroxidases and hydroxyproline-rich proteins. Towards the end of cell elongation there is a large rise in these wall components and thereafter a continuing slow rise which is associated with increasing age of tissue. Ethylene at concentrations of 0.1 ppm or more increases both peroxidase activity and hydroxyproline levels in the walls, the greatest response occurring in immature tissue including the apical hook. Growth of these tissues is highly sensitive to ethylene which causes an inhibition of elongation in extending cells and an enhanced lateral cell expansion. We suggest that the effects of ethylene on wall-bound peroxidase and hydroxyproline are implicated in the ethylene regulation of cell growth.
The covalently bound wall peroxidase was found to be extremely stable and to contain unique isoenzymes which do not occur in either the cytoplasm or in the peroxidase which is ionically bound to walls. Ethylene increases peroxidase activity in both the cytoplasmic and the ionically bound wall fractions, but there is little or no increase in their hydroxyproline content. The possible relationships between covalently bound wall peroxidase and hydroxyproline are discussed and we speculate that this peroxidase may be involved in the hydroxylation of proline in the walls.
Systemic acquired resistance induced in intact ‘Samsun NN’ tobacco plants by either tobacco mosaic virus (TMV) or tobacco
necrosis virus (TNV) was more effective against challenge inoculation with the same than with the other of the two viruses.
However, in trimmed ‘Samsun NN’ plants resistance induced by either of these viruses was stronger against TMV than against
TNV. In intact ‘Samsun’ tobacco plants TNV induced a systemic resistance against itself identical to the one expressed in
‘Samsun NN’. Moreover, it induced systemic resistance against TMV as based on a decrease in TMV content in challeng-inoculated
leaves. These observations indicate that systemic acquired resistance is not limited to combinations in which both inducing
and challenging virus give rise to a hypersensitive reaction, and further point to virus-specific factors regulating the extent
of resistance expressed.
Peroxidase activities and isozyme patterns were determined in tobacco leaves of the cultivar Bottom Special in which disease resistance had been induced by prior infiltration with heat-killed Pseudomonas solanacearum B1 cells. As compared with unprotected leaves, soluble peroxidase activity increased by 8 h after infiltration and an additional isozyme band (P1) appeared by 12 h. There were no changes in either ionically or covalently bound forms of peroxidase. Similar changes in peroxidase were observed in leaves that were infiltrated with killed bacteria and then shaded with aluminum foil, although protection was not obtained under these conditions. Similarly, in leaves infiltrated with heat-killed saprophytic bacteria (Escherichia coli B, Bacillus subtilis) which did not induce protection, peroxidase activity was increased and the P1 band appeared.Lipopolysaccharide from K60 cells of Pseudomonas solanacearum, which induced protection, also increased peroxidase activity and caused appearance of the P1 band. When leaf cells were wounded by injection with asbestos fibers, peroxidase activity increased but the P1 band was not visible.It was concluded that peroxidase increases are not directly involved in disease resistance, and probably result from injury caused by toxic compounds in the bacterial cell suspension.
Infection of the first true leaf of cucumber with Colletotrichum lagenarium induces systemic resistance (protection) against subsequent challenge by C. lagenarium or Cladosporium cucumerinum Conidia of C. lagenarium germinated and formed appressoria equally well on isolated epidermal strips from protected and control plants; however, penetration occurred less frequently into epidermal strips from protected plants. Inhibition of penetration was associated with host epidermal cell wall lignification directly under appressoria. Lignification occurred more rapidly and to a greater extent in protected than in control plants. Infection of etiolated seedlings resistant to scab with C. cucumerinum made the seedlings resistant to C. lagenarium, and elicited a rapid lignification of penetrated and adjacent host cells. This lignification reaction in the resistant cultivar was histologically indistinguishable from that at sites of penetration in a systemically protected “susceptible” cultivar challenged with C. cucumerinum. Germination of conidia and frequencies of penetration of C. cucumerinum were similar in protected and control plants, but development of the fungus in lignified tissue was markedly restricted. Coniferyl alcohol, a lignin precursor, was toxic to C. lagenarium and C. cucumerinum when only 0·3 hg were applied to thin-layer bioassay plates. This suggests that it might function as a phytoalexin. Mycelia of C. lagenarium and C. cucumerinum were “lignified” in the presence of coniferyl alcohol, peroxidase and hydrogen peroxide.
A cultivar of cucumber susceptible to Colletotrichum lagenarium race 1 was systemically protected against disease caused by the fungus by prior infection with tobacco necrosis virus (TNV). Infection of one cotyledon with the virus protected the opposite cotyledon and the first true leaf against disease caused by a subsequent infection with C. lagenarium. Autoclaved sap from TNV-infected plants or sap from non-inoculated plants did not elicit protection. Infection with the virus prior to infection with C. lagenarium caused a reduction in the number and size of lesions caused by the fungus at low spore concentrations, but was less effective against higher spore concentrations. The number of lesions formed on a TNV-infected cotyledon was not affected by prior infection of the opposite cotyledon with TNV or C. lagenarium.
Systemic acquired resistance of Nicotiana tabacum cv. Samsun NN to tobacco mosaic virus, expressed primarily as a decrease in lesion size, is associated with increased initial peroxidase and catalase activities. The increase in peroxidase activity was positively correlated with the lesion density on inoculated leaves, but the level of resistance attained was influenced little either by the initial inoculum concentration or by the leaf position on the stem.In non-infected tobacco plants peroxidase activity progressively increases with leaf age. In young, expanding leaves no correlation between peroxidase activity and lesion size was observed (r = 0·05), whereas in mature, fully grown leaves an inverse logarithmic relationship exists (r = 0·99). No definite proportionality between catalase activity and lesion size was apparent. Leaves showing systemic resistance had properties characteristic of older leaves, but the decrease in lesion size was larger than could be accounted for on the basis of peroxidase alone. Artificial ageing, trimming of plants, root inundation, drought or salt-stress stimulated peroxidase activity but, upon subsequent inoculation, also enhanced lesion enlargement. Injection of leaves with tobacco or horseradish peroxidase either had no effect on, or increased, lesion size. No correlations between changes in individual peroxidase isoenzymes and effects on lesion size were noted.Peroxidase activity thus seems to be a reflection of a physiological state rather than being directly responsible for regulating the rate of lesion enlargement.
Eight cultivars of cucumber, susceptible to Colletotrichum lagenarium race 1, were systemically protected against disease caused by the pathogen by prior inoculation with race 1 of the pathogen. Inoculation of a single leaf of young cucumber plants with a spore suspension of C. lagenarium protected the leaf above against disease caused by a subsequent inoculation with C. lagenarium. Repeated inoculations of protected plants enhanced protection and plants remained protected throughout the 10-week duration of experiments. New growth of protected and repeatedly inoculated plants was symptomless. Protection was also elicited by low levels of inoculum which caused 2 to 10 lesions/plant. Damage to a leaf by dry ice did not protect the leaf above against C. lagenarium. After the unprotected leaf developed symptoms, it elicited protection for the leaf above and this leaf was often symptomless. Though Cladosporium cucumerinum protected cucumber cultivars resistant to C. cucumerinum against C. lagenarium, C. lagenarium protected cucumber varieties against C. lagenarium regardless of their resistance or susceptibility to C. cucumerinum. The phenomenon of protection reported suggests a remarkable elasticity and versatility inherent in a plant's mechanism for disease resistance.
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 high proportion of the soluble peroxidase of tobacco (Nicotiana tabacum L. var. Bottom Special) leaves is found in the fluid obtained by centrifugation of a buffer solution previously infiltrated into the intercellular spaces. Only a very small amount of the cytoplasmic enzyme, glucose 6-phosphate dehydrogenase, is present in this fluid. Specific activity data suggest that an active process is responsible for the transfer of soluble peroxidase to the intercellular space and that the intercellular fluid fraction is not simply composed of material moving out of leaf cells by diffusion. The centrifugation method is a satisfactory means of isolating diluted intercellular fluid for biochemical and physiological investigations.
Kud Gel electrophoresis was carried out in 7.5% polyacrylamide gels in 7.5 cm glass tubes (O-5 cm inner diameter)
- Analysis
- R Peroxidase
- E M Hammerschmidt
- Nuckles
Analysis of peroxidase isoymes R. Hammerschmidt, E. M. Nuckles and J. Kud Gel electrophoresis was carried out in 7.5% polyacrylamide gels in 7.5 cm glass tubes (O-5 cm inner diameter) at pH 9.3 [II].
Enhanced peroxidase activity and lignification in the induced systemic resistance of cucumber
- Hammerschmidt
Die lokalisation der Peroxidase-Isoenxymgruppe GI in der Zellwand von Tobak-Geweben
- Mäder
Induction of systemic resistance in cucurbits to anthracnose and tobacco necrosis virus
- Jenns