Exogenous priming of chitosan induces upregulation of phytohormones and resistance against cucumber powdery mildew disease is correlated with localized biosynthesis of defense enzymes

Novel Biological-Based Strategy for Synthesis of Green Nanochitosan and Copper-Chitosan Nanocomposites: Promising Antibacterial and Hematological Agents

Two novel samples of nanoparticles based on chitosan were greenly synthesized using pomegranate peel extract. The extract served as a nanoparticle precursor, facilitating the precipitation of nanosized chitosan through the ionic gelation method. Additionally, by mixing the green chitosan nanoparticles with copper ions, a nanoscale composite of chitosan and copper oxide was also produced. Structural and morphological investigations (FTIR, XRD, SEM, EDX, and TGA analyses) were performed for greenly synthesized chitosan nanoparticles and their copper oxide composite to determine all the significant characteristics of those nanoparticles. In addition, both samples were tested using some biological investigations, such as antimicrobial activity and hematological effects. The antimicrobial tests yielded promising results for both the green chitosan nanoparticles and the CuO composite when tested using two bacterial strains and two fungal strains. Moreover, the results showed that using a similar concentration of both green-based chitosan samples resulted in a slightly larger inhibition zone and a lower minimum inhibition concentration (MIC) for the copper oxide chitosan composite compared to the chitosan nanoparticles for all microorganisms included in the test. The mean count of blood components (RBCs and platelets), clotting time, and cholesterol levels in three different blood samples were used to indicate the hematological activity of both greenly synthesized nanoparticles. The results verified a slight reduction in blood component count after the addition of green chitosan nanoparticles, but the chitosan copper oxide composite did not have a noticeable effect on the three blood samples. The chitosan nanoparticles were able to cause a considerable reduction in clotting time and cholesterol levels for all blood samples, thus acting as procoagulants. However, the mixing of CuO with chitosan nanoparticles prolonged the rate of clotting in blood samples from hypercholesteremic individuals, and thus, the mixture acted as an anticoagulant agent.

Green synthesis of chitosan nanoparticles using tea extract and its antimicrobial activity against economically important phytopathogens of rice

The aim of the present work is to biosynthesize Chitosan nanoparticles (CTNp) using tea (Camellia sinensis) extract, with potent antimicrobial properties towards phytopathogens of rice. Preliminary chemical analysis of the extract showed that they contain carbohydrate as major compound and uronic acid indicating the nature of acidic polysaccharide. The structure of the isolated polysaccharide was analyzed through FTIR and 1H NMR. The CTNp was prepared by the addition of isolated tea polysaccharides to chitosan solution. The structure and size of the CTNp was determined through FTIR and DLS analyses. The surface morphology and size of the CTNp was analysed by SEM and HRTEM. The crystalinity nature of the synthesized nanoparticle was identified by XRD analysis. The CTNp exhibited the antimicrobial properties against the most devastating pathogens of rice viz., Pyricularia grisea, Xanthomonas oryzae under in vitro condition. CTNp also suppressed the blast and blight disease of rice under the detached leaf assay. These results suggest that the biosynthesized CTNp can be used to control the most devastating pathogens of rice.

Exogenous priming of chitosan induces resistance in Chinese prickly ash against stem canker caused by Fusarium zanthoxyli

Stem canker is a highly destructive disease that threatens prickly ash plantations in China. This study demonstrated the effective control of stem canker in prickly ash using chitosan priming, reducing lesion areas by 46.77 % to 75.13 % across all chitosan treatments. The mechanisms underlying chitosan-induced systemic acquired resistance (SAR) in prickly ash were further investigated. Chitosan increased H2O2 levels and enhanced peroxidase and catalase enzyme activities. A well-constructed regulatory network depicting the genes involved in the SAR and their corresponding expression levels in prickly ash plants primed with chitosan was established based on transcriptomic analysis. Additionally, 224 ZbWRKYs were identified based on the whole genome of prickly ash, and their phylogenetic evolution, conserved motifs, domains and expression patterns of ZbWRKYs were comprehensively illustrated. The expression of 12 key genes related to the SAR was significantly increased by chitosan, as determined using reverse transcription-quantitative polymerase chain reaction. Furthermore, the activities of defensive enzymes and the accumulation of lignin and flavonoids in prickly ash were significantly enhanced by chitosan treatment. Taken together, this study provides valuable insights into the chitosan-mediated activation of the immune system in prickly ash, offering a promising eco-friendly approach for forest stem canker control.

Chitosan, chitosan derivatives, and chitosan-based nanocomposites: eco-friendly materials for advanced applications (a review)

For many years, chitosan has been widely regarded as a promising eco-friendly polymer thanks to its renewability, biocompatibility, biodegradability, non-toxicity, and ease of modification, giving it enormous potential for future development. As a cationic polysaccharide, chitosan exhibits specific physicochemical, biological, and mechanical properties that depend on factors such as its molecular weight and degree of deacetylation. Recently, there has been renewed interest surrounding chitosan derivatives and chitosan-based nanocomposites. This heightened attention is driven by the pursuit of enhancing efficiency and expanding the spectrum of chitosan applications. Chitosan's adaptability and unique properties make it a game-changer, promising significant contributions to industries ranging from healthcare to environmental remediation. This review presents an up-to-date overview of chitosan production sources and extraction methods, focusing on chitosan's physicochemical properties, including molecular weight, degree of deacetylation and solubility, as well as its antibacterial, antifungal and antioxidant activities. In addition, we highlight the advantages of chitosan derivatives and biopolymer modification methods, with recent advances in the preparation of chitosan-based nanocomposites. Finally, the versatile applications of chitosan, whether in its native state, derived or incorporated into nanocomposites in various fields, such as the food industry, agriculture, the cosmetics industry, the pharmaceutical industry, medicine, and wastewater treatment, were discussed.

Chitosan nanoparticles upregulate C and N metabolism in soybean plants grown under elevated levels of atmospheric carbon dioxide

Despite the wide utilization of chitosan nanoparticles (CSNPs) as a promising approach for sustainable agriculture, their efficiency under elevated CO2 (eCO2), has not been evaluated. The interactive effects of CSNPs and eCO2 were evaluated on the growth and C and N metabolism of soybean plants. Plants were treated with CSNPs and grown under ambient CO2 (410 ppm, aCO2) or eCO2 (645 ppm). Regardless of CO2 level, CSNPs improved the net photosynthetic rate. CSNPs aggravated the effect of eCO2 treatment on the levels of non-structural carbohydrates (i.e., glucose, fructose, sucrose, and starch), especially in shoots, which was inconsistence with the upregulation of carbohydrates metabolizing enzymes. Being the most pivotal energetic and signaling organic compounds in higher plants, the synergistic action of CSNPs and eCO2 on the accumulation of soluble sugars upregulated the N metabolism as indicated by induced activities of nitrate reductase, arginase, glutamate dehydrogenase, glutamine synthetase, and glutamine oxoglutarate aminotransferase which was manifested finally as increased shoot and root total nitrogen content as well as proline and aspartate in roots. At the hormonal level, the coexistence of eCO2 with CSNPs further supports their positive impact on the contents of IAA and, to a lesser extent, GAs. The present data prove that the biofertilization capacity of CSNPs is even more potent under futuristic eCO2 levels and could even further improve the growth and resilience of plants.

Strategies for the Preparation of Chitosan Derivatives for Antimicrobial, Drug Delivery, and Agricultural Applications: A Review

Chitosan has received much attention for its role in designing and developing novel derivatives as well as its applications across a broad spectrum of biological and physiological activities, owing to its desirable characteristics such as being biodegradable, being a biopolymer, and its overall eco-friendliness. The main objective of this review is to explore the recent chemical modifications of chitosan that have been achieved through various synthetic methods. These chitosan derivatives are categorized based on their synthetic pathways or the presence of common functional groups, which include alkylated, acylated, Schiff base, quaternary ammonia, guanidine, and heterocyclic rings. We have also described the recent applications of chitosan and its derivatives, along with nanomaterials, their mechanisms, and prospective challenges, especially in areas such as antimicrobial activities, targeted drug delivery for various diseases, and plant agricultural domains. The accumulation of these recent findings has the potential to offer insight not only into innovative approaches for the preparation of chitosan derivatives but also into their diverse applications. These insights may spark novel ideas for drug development or drug carriers, particularly in the antimicrobial, medicinal, and plant agricultural fields.

High-Density Chitosan Induces a Biochemical and Molecular Response in Coffea arabica during Infection with Hemileia vastatrix

The coffee industry faces coffee leaf rust caused by Hemileia vastratix, which is considered the most devastating disease of the crop, as it reduces the photosynthetic rate and limits productivity. The use of plant resistance inducers, such as chitosan, is an alternative for the control of the disease by inducing the synthesis of phytoalexins, as well as the activation of resistance genes. Previously, the effect of chitosan from different sources and physicochemical properties was studied; however, its mechanisms of action have not been fully elucidated. In this work, the ability of food-grade high-density chitosan (0.01% and 0.05%) to control the infection caused by the pathogen was evaluated. Subsequently, the effect of high-density chitosan (0.05%) on the induction of pathogenesis-related gene expression (GLUC, POX, PAL, NPR1, and CAT), the enzymatic activity of pathogenesis-related proteins (GLUC, POX, SOD, PPO, and APX), and phytoalexin production were evaluated. The results showed that 0.05% chitosan increased the activity and gene expression of ß-1,3 glucanases and induced a differentiated response in enzymes related to the antioxidant system of plants. In addition, a correlation was observed between the activities of polyphenol oxidase and the production of phytoalexin, which allowed an effective defense response in coffee plants.

Relative biochemical and physiological docking of cucumber varieties for supporting innate immunity against Podosphaera xanthii

Powdery mildew in cucumber is caused by the Podosphaera xanthii. No strategy for improving disease resistance can be successful in the absence of thorough insights into the physiological and biochemical responses of cucumber plants to powdery mildew. Therefore, a field experiment was executed to evaluate five commercial cucumber varieties (V1: Dynasty, V2: Long green, V3:Desi Kheera, V4:Thamin II, V5:Cucumber 363) for their inherent immunity to powdery mildew. Upon inoculating cucumber plants with Podosphaera xanthii, we noted differential responses among the varieties. Compared to other varieties, V1 and V2 showed higher values (P ≤ 0.05) for chlorophyll-a under control and pathogen-attacked plants respectively. The minimum value of anthocyanin content (-53.73%) was recorded in V3 as compared to other varieties post pathogen infection. All pathogen-infected cucumber varieties showed a considerable (P ≤ 0.05) loss in flavonoid content except V2. The maximum destruction for Phenolics under powdery mildew (179%) were recorded in V4, whereas V1 exhibited maximum phenolic content under control conditions. In pathogen-infected plants, the minimum AsA was recorded in V5 as compared to all other varieties. Pathogen invasion impacted significantly (P ≤ 0.05) the activity of superoxide dismutase (SOD). Besides, cucumber plants after pathogen inoculation resulted in a considerable (P ≤ 0.05) increase of peroxidase (POD) activity in V1 (5.02%), V2 (7.5%), and V3 (11%) in contrast to V4. Our results confirmed that cucumber varieties perform differently, which was brought on by distinct metabolic and physiological modifications that have an impact on growth and development. The changes in different attributes were correlated with cucumber resistance against powdery mildew. The results would help us fully harness the potential of these varieties to trigger disease management initiatives and defense responses.

Plant hormesis: Revising of the concepts of biostimulation, elicitation and their application in a sustainable agricultural production

Current research in basic and applied knowledge of plant science has aimed to unravel the role of the interaction between environmental factors and the genome in the physiology of plants to confer the ability to overcome challenges in a climate change scenario. Evidence shows that factors causing environmental stress (stressors), whether of biological, chemical, or physical origin, induce eustressing or distressing effects in plants depending on the dose. The latter suggests the induction of the "hormesis" phenomenon. Sustainable crop production requires a better understanding of hormesis, its basic concepts, and the input variables to make its management feasible. This implies that acknowledging hormesis in plant research could allow specifying beneficial effects to effectively manage environmental stressors according to cultivation goals. Several factors have been useful in this regard, which at low doses show beneficial eustressing effects (biostimulant/elicitor), while at higher doses, they show distressing toxic effects. These insights highlight biostimulants/elicitors as tools to be included in integrated crop management strategies for reaching sustainability in plant science and agricultural studies. In addition, compelling evidence on the inheritance of elicited traits in plants unfolds the possibility of implementing stressors as a tool in plant breeding.

Hormonal and proteomic analyses of southern blight disease caused by Athelia rolfsii and root chitosan priming on Cannabis sativa in an in vitro hydroponic system

Southern blight disease, caused by the fungal pathogen Athelia rolfsii, suppresses plant growth and reduces product yield in Cannabis sativa agriculture. Mechanisms of pathology of this soil-borne disease remain poorly understood, with disease management strategies reliant upon broad-spectrum antifungal use. Exposure to chitosan, a natural elicitor, has been proposed as an alternative method to control diverse fungal diseases in an eco-friendly manner. In this study, C. sativa plants were grown in the Root-TRAPR system, a transparent hydroponic growth device, where plant roots were primed with .2% colloidal chitosan prior to A. rolfsii inoculation. Both chitosan-primed and unprimed inoculated plants displayed classical symptoms of wilting and yellowish leaves, indicating successful infection. Non-primed infected plants showed increased shoot defense responses with doubling of peroxidase and chitinase activities. The levels of growth and defense hormones including auxin, cytokinin, and jasmonic acid were increased 2-5-fold. In chitosan-primed infected plants, shoot peroxidase activity and phytohormone levels were decreased 1.5-4-fold relative to the unprimed infected plants. When compared with shoots, roots were less impacted by A. rolfsii infection, but the pathogen secreted cell wall-degrading enzymes into the root-growth solution. Chitosan priming inhibited root growth, with root lengths of chitosan-primed plants approximately 65% shorter than the control, but activated root defense responses, with root peroxidase activity increased 2.7-fold along with increased secretion of defense proteins. The results suggest that chitosan could be an alternative platform to manage southern blight disease in C. sativa cultivation; however, further optimization is required to maximize effectiveness of chitosan.

Exogenous application of antagonistic Streptomyces sp. SND-2 triggers defense response in Vigna radiata (L.) R. Wilczek (mung bean) against anthracnose infection

Anthracnose is a devastating disease caused by the fungus Colletotrichum lindemuthianum (CL) in Vigna radiata (L.) R. Wilczek (mung bean). In the present study, an eco-friendly approach to control anthracnose infection, growth promotion and enhancement of defense response in mung bean plants using endophytic actinomycetes was performed. Among the 24 actinomycetes isolates from the Cleome rutidosperma plant, the isolate SND-2 exhibited a broad spectrum of antagonistic activity with 63.27% of inhibition against CL in the dual culture method. Further, the isolate SND-2 was identified as Streptomyces sp. strain SND-2 (SND-2) through the 16S rRNA gene sequence. In-vitro screening of plant growth trials confirmed that SND-2 has the potential to produce indole acetic acid, hydrogen cyanide, ammonia, phosphate solubilization, and siderophore. The in-vivo biocontrol study was performed with exogenous application of wettable talcum-based formulation of SND-2 strain to mitigate CL infection in mung bean seedlings. The results displayed maximum seed germination, vigor index, increased growth parameters, and lowest disease severity (43.63 ± 0.73) in formulation treated and pathogen challenged mung bean plants. Further, the application of SND-2 formulation with pathogen witnessed increased cellular defense through the maximum accumulation of lignin, hydrogen peroxide and phenol deposition in mung bean leaves compared with control treatments. Biochemical defense response exhibited upregulation of antioxidant enzymes such as phenylalanine ammonia-lyase, β-1,-3-Glucanase, and peroxidase enzymes activities with increased phenolic (3.64 ± 0.11 mg/g fresh weight) and flavonoid (1.14 ± 0.05 mg/g fresh weight) contents in comparison with other treatments at 0, 4, 12, 24, 36, and 72 h post pathogen inoculation. This study demonstrated that formulation of Streptomyces sp. strain SND-2 is a potential source as a suppressive agent and plant growth promoter in mung bean plants upon C. lindemuthianum infestation and witnesses the elevation in cellular and biochemical defense against anthracnose disease.

Chitosan-induced biotic stress tolerance and crosstalk with phytohormones, antioxidants, and other signalling molecules

Several polysaccharides augment plant growth and productivity and galvanise defence against pathogens. Such elicitors have ecological superiority over traditional growth regulators, considering their amplified biocompatibility, biodegradability, bioactivity, non-toxicity, ubiquity, and inexpensiveness. Chitosan is a chitin-derived polysaccharide that has recently been spotlighted among plant scientists. Chitosan supports plant growth and development and protects against microbial entities such as fungi, bacteria, viruses, nematodes, and insects. In this review, we discuss the current knowledge of chitosan's antimicrobial and insecticidal potential with recent updates. These effects are further explored with the possibilities of chitosan's active correspondence with phytohormones such as jasmonic acid (JA), salicylic acid (SA), indole acetic acid (IAA), abscisic acid (ABA), and gibberellic acid (GA). The stress-induced redox shift in cellular organelles could be substantiated by the intricate participation of chitosan with reactive oxygen species (ROS) and antioxidant metabolism, including hydrogen peroxide (H2O2), superoxide dismutase (SOD), catalase (CAT), and peroxidase (POD). Furthermore, we propose how chitosan could be intertwined with cellular signalling through Ca2+, ROS, nitric oxide (NO), transcription factors (TFs), and defensive gene activation.

The Studies on Chitosan for Sustainable Development: A Bibliometric Analysis

Chitosan is a biocompatible polymer with vast applications in pharmacology, medicine, paper making, agriculture, and the food industry due to its low toxicity. Chitosan also plays an important role in the sustainable environment since chitosan is able to absorb greenhouse gases, harmful organic matter, and heavy ions. Therefore, this paper conducts a bibliometric analysis of chitosan for sustainable development using the Scopus database from 1976 to 2023. A performance analysis on the 8002 documents was performed with Harzing's Publish or Perish. Science mapping was conducted using VOSviewer. The annual publication on chitosan for sustainable development showed an upward trend in recent years as the annual publication peaked in 2022 with 1178 documents with most of the documents being articles and published in journals. Material science, chemistry, and engineering are tightly related subject areas. China had the highest publication of 1560 total documents while the United States had the most impactful publication with 55,019 total citations, 68.77 citations per document, 77.6 citations per cited document, h-index 110, and g-index of 211. India had the largest international collaboration with 572 total link strength. "International Journal of Biological Macromolecules", "Carbohydrate Polymers", and "Polymers" have been identified as the top three source titles that publish the most documents on chitosan for sustainable development. The emerging trends in chitosan on sustainable development focus on the application of chitosan as an antibacterial agent and biosorbent for contaminants, especially in water treatment.

Chitosan nanoparticles support the impact of arbuscular mycorrhizae fungi on growth and sugar metabolism of wheat crop

Arbuscular mycorrhizae fungi (AMF) symbiosis is an indispensable approach in sustainable agriculture. AMF-plant association is likely to be enhanced by the nanoparticle's application. Herein, the impact of chitosan nanoparticles (CSNPs) on the mycorrhizal colonization in wheat has been investigated. The provoked changes in wheat growth, physiology and metabolism were assessed. CSNPs treatment improved AMF colonization (52 %) by inducing the levels of auxins and strigolactones in roots by 32 and 21 %, respectively besides flavonoids exudation into the rhizosphere (9 %). Such supporting action of CSNPs was associated with improved plant biomass production (21 %) compared to AMF treatment. Both treatments synergistically enhanced the photochemical efficiency of photosystem II and stomatal conductance, therefore the photosynthetic rate was increased. The combined application of CSNPs and AMF enhanced accumulation of glucose, fructose, sucrose, and starch (12, 22, 31 and 13 %, respectively), as well as the activities of sucrose-p-synthase, invertases and starch synthase compared to AMF treatment. The synchronous application of CSNPs and AMF promoted the levels of polyphenols, carotenoids, and tocopherols therefore, improved antioxidant capacity (33 %), in the roots. CSNPs can be applied as an efficient biofertilization strategies to enhance plant growth and fitness, beside improvement of health promoting compounds in wheat.

Effect of Seed Priming with Chitosan Hydrolysate on Lettuce (Lactuca sativa) Growth Parameters

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.

Chitosan-Salicylic acid and Zinc sulphate nano-formulations defend against yellow rust in wheat by activating pathogenesis-related genes and enzymes

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.

Increasing the activities of protective enzymes is an important strategy to improve resistance in cucumber to powdery mildew disease and melon aphid under different infection/infestation patterns

Powdery mildew, caused by Sphaerotheca fuliginea (Schlecht.) Poll., and melon aphids (Aphis gossypii Glover) are a typical disease and insect pest, respectively, that affect cucumber production. Powdery mildew and melon aphid often occur together in greenhouse production, resulting in a reduction in cucumber yield. At present there are no reports on the physiological and biochemical effects of the combined disease and pest infection/infestation on cucumber. This study explored how cucumbers can regulate photosynthesis, protective enzyme activity, and basic metabolism to resist the fungal disease and aphids. After powdery mildew infection, the chlorophyll and free proline contents in cucumber leaves decreased, while the activities of POD (peroxidase) and SOD (superoxide dismutase) and the soluble protein and MDA (malondialdehyde) contents increased. Cucumber plants resist aphid attack by increasing the rates of photosynthesis and basal metabolism, and also by increasing the activities of protective enzymes. The combination of powdery mildew infection and aphid infestation reduced photosynthesis and basal metabolism in cucumber plants, although the activities of several protective enzymes increased. Aphid attack after powdery mildew infection or powdery mildew infection after aphid attack had the opposite effect on photosynthesis, protective enzyme activity, and basal metabolism regulation. Azoxystrobin and imidacloprid increased the contents of chlorophyll, free proline, and soluble protein, increased SOD activity, and decreased the MDA content in cucumber leaves. However, these compounds had the opposite effect on the soluble sugar content and POD and CAT (catalase) activities. The mixed ratio of the two single agents could improve the resistance of cucumber to the combined infection of powdery mildew and aphids. These results show that cucumber can enhance its pest/pathogen resistance by changing physiological metabolism when exposed to a complex infection system of pathogenic microorganisms and insect pests.

Chitosan and chitosan-derived nanoparticles modulate enhanced immune response in tomato against bacterial wilt disease

The present study evaluated the priming efficacy of chitosan and chitosan-derived nanoparticles (CNPs) against bacterial wilt of tomato. In the current study, seed-treated CNPs plus pathogen-inoculated tomato seedlings recorded significant protection of 62 % against pathogen-induced wilt disease and subsequently better growth. The induced resistance was witnessed by a prominent increase in lignin, callose and H₂O₂ deposition, followed by superoxide radical accumulation in leaves. Additionally, chitosan and CNPs-treated tomato plants recorded a remarkable increase in the upregulation of phenylalanine ammonia-lyase (PAL), peroxidase (POX), polyphenol oxidase (PPO), catalase (CAT) and β-1, 3 glucanase (GLU) in comparison with untreated plants. The chitosan and CNPs-induced antioxidant enzymes were positively correlated with the stimulation of corresponding gene expression in CNPs treated plants related to pathogen-inoculated ones. The results of this study describe that how the application of chitosan and CNPs elicit defense responses at the cellular, biochemical and gene expression in tomato plants against bacterial wilt disease, thereby improve growth and yield.

Pretreatment with Chitosan Prevents Fusarium Infection and Induces the Expression of Chitinases and β-1,3-Glucanases in Garlic (Allium sativum L.)

Fusarium infection decreases the yield of garlic (Allium sativum L.); however, the knowledge about garlic response to fungal attack is limited. Chitosan induces plant defense response to stress conditions. Here, we analyzed the effects of chitosan with low (Ch1, 39 kDa) and medium (Ch2, 135 kDa) molecular weight on Fusarium infection in garlic. Ch1 and Ch2 at concentrations 0.125–0.400 mg/mL suppressed the growth of Fusarium proliferatum cultures in vitro. Pretreatment of garlic bulbs with Ch1 or Ch2 prevented disease symptoms after F. proliferatum inoculation, while exerting early inhibitory and late stimulatory effects on chitinase and β-1,3-glucanase activities. Ch1/Ch2 treatment of garlic already infected with F. proliferatum caused transcriptional upregulation of chitinases and β-1,3-glucanases at the early stage, which was maintained at the late stage in Ch2-treated samples, but not in Ch1-treated samples, where transcriptional inhibition was observed. The stimulatory effect of Ch2 pretreatment on the expression of chitinase and endo-β-1,3-glucanase genes was stronger than that of Ch1 pretreatment, suggesting that Ch2 could be more effective than Ch1 in pre-sowing treatment of garlic bulbs. Our results provide insights into the effects of chitosan on the garlic response to Fusarium, suggesting a novel strategy to protect garlic crop against fungal infection.

Chitosan as a Tool for Sustainable Development: A Mini Review

New developments require innovative ecofriendly materials defined by their biocompatibility, biodegradability, and versatility. For that reason, the scientific society is focused on biopolymers such as chitosan, which is the second most abundant in the world after cellulose. These new materials should show good properties in terms of sustainability, circularity, and energy consumption during industrial applications. The idea is to replace traditional raw materials with new ecofriendly materials which contribute to keeping a high production rate but also reducing its environmental impact and the costs. The chitosan shows interesting and unique properties, thus it can be used for different purposes which contributes to the design and development of sustainable novel materials. This helps in promoting sustainability through the use of chitosan and diverse materials based on it. For example, it is a good sustainable alternative for food packaging or it can be used for sustainable agriculture. The chitosan can also reduce the pollution of other industrial processes such as paper production. This mini review collects some of the most important advances for the sustainable use of chitosan for promoting circular economy. Hence, the present review focuses on different aspects of chitosan from its synthesis to multiple applications.

The Complex Metabolomics Crosstalk Triggered by Four Molecular Elicitors in Tomato

The elicitation of plant secondary metabolism may offer interesting opportunities in the framework of sustainable approaches in plant science and in terms of their ability to prime resistance to biotic and abiotic stressors. The broad metabolic reprogramming triggered by different molecular elicitors, namely salicylate (SA), polyamines (PAs), and chitosan, was comprehensively investigated using a metabolomics approach and the tomato (Solanum lycopersicum L.) as the model crop. Six different treatments were compared: a negative control (no treatments), a second negative control treated with 1 M acetic acid (the reference for chitosan, since chitosan was solubilized in acetic acid), and four molecular elicitors, 1 mM 2,1,3-benzothiadiazole (BTH, a positive control), 10 mg/mL chitosan, 0.01 mM SA, and a 0.1 mM PA (putrescine, spermidine, and spermine). All treatments determined a slight increase in biomass, in particular following PA treatment. A broad reprogramming of secondary metabolism could be observed, including membrane lipid remodeling, phenylpropanoid antioxidants, and phytohormone crosstalk. Overall, our results suggest that PAs, SA, and BTH shared a systemic acquired resistance (SAR)-related response, whereas chitosan induced a more distinct induced systemic resistance (ISR)-like jasmonate-related response. These results pave the way towards the possible use of elicitors as a sustainable tool in plant science and agriculture by increasing crop resilience to biotic and abiotic stressors without detrimental effects on plant biomass.

Efficacy of Chitosan Nanoparticle Loaded-Salicylic Acid and -Silver on Management of Cassava Leaf Spot Disease

Leaf spot is one of the most important cassava diseases. Nanotechnology can be applied to control diseases and improve plant growth. This study was performed to prepare chitosan (CS) nanoparticle (NP)-loaded salicylic acid (SA) or silver (Ag) by the ionic gelation method, and to evaluate their effectiveness on reducing leaf spot disease and enhancing the growth of cassava plants. The CS (0.4 or 0.5%) and Pentasodium triphosphate (0.2 or 0.5%) were mixed with SA varying at 0.05, 0.1, or 0.2% or silver nitrate varying at 1, 2, or 3 mM to prepare three formulations of CS-NP-loaded SA named N1, N2, and N3 or CS-NP-loaded Ag named N4, N5, and N6. The results showed that the six formulations were not toxic to cassava leaves up to 800 ppm. The CS-NP-loaded SA (N3) and CS-NP-loaded Ag (N6) were more effective than the remaining formulations in reducing the disease severity and the disease index of leaf spot. Furthermore, N3 at 400 ppm and N6 at 200, 400, and 800 ppm could reduce disease severity (68.9–73.6% or 37.0–37.7%, depending on the time of treatment and the pathogen density) and enhance plant growth more than or equal to commercial fungicide or nano-fungicide products under net-house conditions. The study indicates the potential to use CS-NP-loaded SA or Ag as elicitors to manage cassava leaf spot disease.

How do plants defend themselves against pathogens-Biochemical mechanisms and genetic interventions

In agro-ecosystem, plant pathogens hamper food quality, crop yield, and global food security. Manipulation of naturally occurring defense mechanisms in host plants is an effective and sustainable approach for plant disease management. Various natural compounds, ranging from cell wall components to metabolic enzymes have been reported to protect plants from infection by pathogens and hence provide specific resistance to hosts against pathogens, termed as induced resistance. It involves various biochemical components, that play an important role in molecular and cellular signaling events occurring either before (elicitation) or after pathogen infection. The induction of reactive oxygen species, activation of defensive machinery of plants comprising of enzymatic and non-enzymatic antioxidative components, secondary metabolites, pathogenesis-related protein expression (e.g. chitinases and glucanases), phytoalexin production, modification in cell wall composition, melatonin production, carotenoids accumulation, and altered activity of polyamines are major induced changes in host plants during pathogen infection. Hence, the altered concentration of biochemical components in host plants restricts disease development. Such biochemical or metabolic markers can be harnessed for the development of "pathogen-proof" plants. Effective utilization of the key metabolites-based metabolic markers can pave the path for candidate gene identification. This present review discusses the valuable information for understanding the biochemical response mechanism of plants to cope with pathogens and genomics-metabolomics-based sustainable development of pathogen proof cultivars along with knowledge gaps and future perspectives to enhance sustainable agricultural production.

Priming seeds for the future: Plant immune memory and application in crop protection

Plants have evolved adaptive strategies to cope with pathogen infections that seriously threaten plant viability and crop productivity. Upon the perception of invading pathogens, the plant immune system is primed, establishing an immune memory that allows primed plants to respond more efficiently to the upcoming pathogen attacks. Physiological, transcriptional, metabolic, and epigenetic changes are induced during defense priming, which is essential to the establishment and maintenance of plant immune memory. As an environmental-friendly technique in crop protection, seed priming could effectively induce plant immune memory. In this review, we highlighted the recent advances in the establishment and maintenance mechanisms of plant defense priming and the immune memory associated, and discussed strategies and challenges in exploiting seed priming on crops to enhance disease resistance.

Proteomic and physiological analysis provides an elucidation of Fusarium proliferatum infection causing crown rot on banana fruit

Fusarium proliferatum causes the crown rot of harvested banana fruit but the underling infection mechanism remains unclear. Here, proteomic changes of the banana peel with and without inoculation of F. proliferatum were evaluated. In addition, we investigated the effects of F. proliferatum infection on cell structure, hormone content, primary metabolites and defense-related enzyme activities in the banana peel. Our results showed that F. proliferatum infection mainly affects cell wall components and inhibits the activities of polyphenoloxidase, peroxidase, and chitinase. Gel free quantitative proteomic analysis showed 92 down-regulated and 29 up-regulated proteins of banana peel after F. proliferatum infection. These proteins were mainly related to defense response to biotic stress, chloroplast structure and function, JA signaling pathway, and primary metabolism. Although jasmonic acid (JA) content and JA signaling component coronatine-insensitive (COI) protein were induced by F. proliferatum infection, JA-responsible defense genes/proteins were downregulated. In contrast, expression of senescence-related genes was induced by F. proliferatum, indicating that F. proliferatum modulated the JA signaling to accelerate the senescence of banana fruit. Additionally, salicylic acid (SA) content and SA signaling for resistance acquisition were inhibited by F. proliferatum. Taken together, these results suggest that F. proliferatum depolymerizes the cell wall barrier, impairs the defense system in banana fruit, and activates non-defensive JA-signaling pathway accelerated the senescence of banana fruit. This study provided the elucidation of the prominent pathways disturbed by F. proliferatum in banana fruit, which will facilitate the development of a new strategy to control crown rot of banana fruit and improvement of banana cultivars.

Phytotoxicological effects of engineered nanoparticles: An emerging nanotoxicology

Recent innovations in the field of nanoscience and technology and its proficiency as a part of inter-disciplinary science has set an eclectic display in innumerable branches of science, a majority in aliened health science of human and agriculture. Modern agricultural practices have been shifting towards the implementation of nanotechnology-based solutions to combat various emerging problems ranging from safe delivery of nutrients to sustainable approaches for plant protection. In these processes, engineered nanoparticles (ENPs) are widely used as nanocarriers (to deliver nutrients and pesticides) due to their high permeability, efficacy, biocompatibility, and biodegradability properties. Even though the constructive nature of nanoparticles (NPs), nanomaterials (NMs), and other modified or ENPs towards sustainable development in agriculture is referenced, the darker side i.e., eco-toxicological effects is still not covered to a larger extent. The overwhelming usage of these trending NMs has led to continuous persistence in the ecosystem, and their interface with the biotic and abiotic community, degradation lanes and intervention, which might lead to certain beneficial or malefic effects. Metal oxide NPs and polymeric NPs (Alginate, chitosan, and polyethylene glycol) are the most used ENPs, which are posing the nature of beneficial as well as environmentally concerning hazardous materials depending upon their fate and persistence in the ecosystem. The cautious usage of NMs in a scientific way is most essential to harness beneficial aspects of NMs in the field of agriculture whilst minimizing the eco-toxicological effects. The current review is focused on the toxicological effects of various NMs on plant physiology and health. It details interactions of plant intracellular components between applied/persistent NMs, which have brought out drastic changes in seed germination, crop productivity, direct and indirect interaction at the enzymatic as well as nuclear levels. In conclusion, ENPs can pose as genotoxicants that may alter the plant phenotype if not administered appropriately.

Trehalose: A mycogenic cell wall elicitor elicit resistance against leaf spot disease of broccoli and acts as a plant growth regulator

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Mycogenic cell wall elicitor was isolated from trichoderma atroviride.

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The isolated elicitor was identified as trehalose by LC-MS analysis.

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Seed priming with elicitor enhanced early germination and vigour.

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Primed plants induced resistance against leaf spot disease of brocolli.

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Trehalose sugar act as a bio-stimulant for growth promotion and plant defence.

Elicitors are biochemicals, and the cell wall-derived elicitors from fungi can trigger defence mechanisms in plants by increasing the phytoalexin accumulation when they encounter the pathogens. The main objective of this research was to purify and characterize a cell wall elicitor from Trichoderma atroviride (TaCWE) and evaluate the seed priming effect of that elicitor for inducing systemic resistance in broccoli plants against leaf spot disease. Amongst the tested TaCWE concentrations of the seed priming (5, 10, & 25 mg ml⁻¹), 10.0 mg ml⁻¹ showed significantly (P < 0.05) improved early emergence, the rate of germination at 94%, and observed seedling vigour of 2601. Also, elicitor (10 mg ml⁻¹) treatment alone induced 57% plant protection. On the contrary, the elicitor treated and pathogen inoculated plants induced a notable 72% protection against leaf spot disease of broccoli caused by A. brassicicola. Thus, the primed seeds with elicitor showed induced disease resistance and plant growth promotion. The prominent molecule present in the purified extracted cell wall elicitor is confirmed as trehalose. The AFM analysis indicated the trehalose length and width as 10.16 µm and 2.148 µm, respectively. FTIR chromatogram further confirmed trehalose in abundance with traces of carbon, hydrogen, nitrogen, oxygen, and LC-MS profile with a single peak eluted with a retention time of 3.78 min. The findings of this study contribute to understanding better the role of trehalose, a biogenic cell-wall elicitor that can induce systemic resistance against leaf spot disease and regulate plant growth in the broccoli plants.

Gene delivery strategies for therapeutic proteins production in plants: Emerging opportunities and challenges

There are sharply rising demands for pharmaceutical proteins, however shortcomings associated with traditional protein production methods are obvious. Genetic engineering of plant cells has gained importance as a new strategy for protein production. But most current genetic manipulation techniques for plant components, such as gene gun bombardment and Agrobacterium mediated transformation are associated with irreversible tissue damage, species-range limitation, high risk of integrating foreign DNAs into the host genome, and complicated handling procedures. Thus, there is urgent expectation for innovative gene delivery strategies with higher efficiency, fewer side effect, and more practice convenience. Materials based nanovectors have established themselves as novel vehicles for gene delivery to plant cells due to their large specific surface areas, adjustable particle sizes, cationic surface potentials, and modifiability. In this review, multiple techniques employed for plant cell-based genetic engineering and the applications of nanovectors are reviewed. Moreover, different strategies associated with the fusion of nanotechnology and physical techniques are outlined, which immensely augment delivery efficiency and protein yields. Finally, approaches that may overcome the associated challenges of these strategies to optimize plant bioreactors for protein production are discussed.

Mitigation of organophosphorus insecticides from environment: Residual detoxification by bioweapon catalytic scavengers

Organophosphorus insecticides (OPIs) have low persistence and are easily biodegradable in nature. The United States and India are the major countries producing OPIs of about 25% and 17% of the world, respectively. OPIs commonly used for agricultural practices occupy a major share in the global market, which leads to the increasing contamination of OPIs residues in various food chains. To overcome this issue, an enzymatic degradation method has been approved by several environmental toxic, and controlling agencies, including United States Environmental Protection Agency (USEPA). Different catalytic enzymes have been isolated and identified from various microbial sources to neutralize the toxic pesticides and/or insecticides. In this review, we have gathered information on OPIs biotransformation and their residual toxicity in the environment. Particularly, it focuses on OPIs degrading enzymes such as chlorpyrifos hydrolase, diisopropylfluorophosphatase, organophosphate acid anhydrolase, organophosphate hydrolases, and phosphotriesterases like lactonasesspecific activity either P-O link group type or P-S link group of pesticides. To summarize, the catalytic degradation of organophosphorus insecticides is not only profitable but also environmentally friendly. Hence, the enzymatic catalyst is an ultimate and super bio-weapon to mitigate or decontaminate various OPIs residues in both terrestrial and aqueous environments.

Genome-Wide Identification, Diversification, and Expression Analysis of Lectin Receptor-Like Kinase (LecRLK) Gene Family in Cucumber under Biotic Stress

Members of the lectin receptor-like kinase (LecRLKs) family play a vital role in innate plant immunity. Few members of the LecRLKs family have been characterized in rice and Arabidopsis, respectively. However, little literature is available about LecRLKs and their role against fungal infection in cucumber. In this study, 60 putative cucumber LecRLK (CsLecRLK) proteins were identified using genome-wide analysis and further characterized into L-type LecRLKs (24) and G-type LecRLKs (36) based on domain composition and phylogenetic analysis. These proteins were allocated to seven cucumber chromosomes and found to be involved in the expansion of the CsLecRLK gene family. Subcellular localization of CsaLecRLK9 and CsaLecRLK12 showed green fluorescence signals in the plasma membrane of leaves. The transcriptional profiling of CsLecRLK genes showed that L-type LecRLKs exhibited functional redundancy as compared to G-type LecRLKs. The qRT-PCR results indicated that both L- and G-type LecRLKs showed significant response against plant growth-promoting fungi (PGPF-Trichoderma harzianum Rifai), powdery mildew pathogen (PPM-Golovinomyces orontii (Castagne) V.P. Heluta), and combined (PGPF+PPM) treatments. The findings of this study contribute to a better understanding of the role of cucumber CsLecRLK genes in response to PGPF, PPM, and PGPF+PPM treatments and lay the basis for the characterization of this important functional gene family.

Sustainable Agriculture Systems in Vegetable Production Using Chitin and Chitosan as Plant Biostimulants

Chitin and chitosan are natural compounds that are biodegradable and nontoxic and have gained noticeable attention due to their effective contribution to increased yield and agro-environmental sustainability. Several effects have been reported for chitosan application in plants. Particularly, it can be used in plant defense systems against biological and environmental stress conditions and as a plant growth promoter—it can increase stomatal conductance and reduce transpiration or be applied as a coating material in seeds. Moreover, it can be effective in promoting chitinolytic microorganisms and prolonging storage life through post-harvest treatments, or benefit nutrient delivery to plants since it may prevent leaching and improve slow release of nutrients in fertilizers. Finally, it can remediate polluted soils through the removal of cationic and anionic heavy metals and the improvement of soil properties. On the other hand, chitin also has many beneficial effects such as plant growth promotion, improved plant nutrition and ability to modulate and improve plants’ resistance to abiotic and biotic stressors. The present review presents a literature overview regarding the effects of chitin, chitosan and derivatives on horticultural crops, highlighting their important role in modern sustainable crop production; the main limitations as well as the future prospects of applications of this particular biostimulant category are also presented.

Current trends and challenges in the synthesis and applications of chitosan-based nanocomposites for plants: A review

Chitosan, a low-cost and multipurpose polymer with numerous desired physicochemical and biological properties has been tested for various applications in agriculture, pharmacy, and biomedicine industries. The availability of functional groups along the backbone makes chitosan readily available for other polymers and metal ions to form bio-nanocomposites. Different types of chitosan-based nanocomposites have been designed and tested for the enhancement of chitosan efficiency and ultimately widening the application areas of chitosan in plants. These nanocomposites serve different purposes such as eliciting plant's defence systems against different threats (pathogen attack), antimicrobial agent against bacteria, fungi and viruses, enhancement of nutrient uptake by plants, control release of micro/macronutrients, fungicides and herbicides. In this review, an extensive outlook has been provided (mainly in the last five years) to recent trends and advances in the fabrication and application of chitosan-based composites. Finally, current challenges and future development opportunities of chitosan-based nanocomposites for plants are discussed.

Gamma-irradiated fenugreek extracts mediates resistance to rice blast disease through modulating histochemical and biochemical changes

The impact of gamma radiation on the activation of rice innate immunity to blast disease caused by Magnaporthe oryzae is described. In the present study, fenugreek seed extracts radiated with different doses of gamma rays viz. 5Gy, 10Gy, 15Gy, 20Gy and 25Gy were examined for their presence of biocompounds as well as for its ability to induce plant growth promotion and resistance against rice blast disease. The results of GC-MS analysis detected antimicrobial properties in methanolic extract. Enhanced germination (97%) and vigor (2718) was noticed in seeds pretreated with 20 Gy of gamma radiation in comparison with non-irradiated controls. Under greenhouse conditions, a significant disease protection of 56.7% on 3rd and 4th day after inoculation against rice blast was observed in 15Gy-irradiated rice plants challenge-inoculated with M. oryzae. Further, a significant increase in the hydrogen peroxide, phenol and lignin deposition was noticed in 20Gy-irradiated rice plants. Additionally, rice plants pretreated with 15Gy induced maximum activities of peroxidase (POX) and polyphenol oxidase (PPO) compared to untreated control plants. These findings revealed that rice plants-pretreated with gamma radiation elicit resistance against rice blast disease as well as strengthening the growth parameters by modulating cellular and biochemical defense system.

Improvement of Phenylpropanoid Production with Elicitor Treatments in Pimpinella brachycarpa Nakai

Pimpinella brachycarpa Nakai, known as cham-na-mul in Korea, is a popular edible herb and vegetable. Phenolic compounds are recognized as a vital group of plant secondary metabolites that provide innumerable, valuable therapeutic properties. Elicitors are biofactors or chemicals from diverse sources that can trigger morphological and physiological responses in the target organism. This study examined the effect of methyl jasmonate (MeJA), salicylic acid (SA), and chitosan treatment on the accretion of phenolic compounds in P. brachycarpa Nakai. This plant was harvested under different concentration of elicitor treatment for time course. Eight phenolic compounds including were detected in response to elicitor using HPLC. While the untreated controls showed the lowest phenolic content, treatment with 0.3% chitosan, 0.1 mM SA, and 0.1 mM MeJA resulted in 1.43-, 1.39-, and 1.35-fold increase in the phenolic content, respectively. The highest content of most of the individual phenolic compounds followed a similar trend according to treatment type, with chitosan treatment showing the highest content, followed by SA and then MeJA treatments. Thus, we demonstrate that the treatment with optimal concentrations of these elicitors for an optimal period of time increases the production of phenolic compounds in P. brachycarpa Nakai.

Myco-engineered selenium nanoparticles elicit resistance against tomato late blight disease by regulating differential expression of cellular, biochemical and defense responsive genes

With the advent of rapid evolution of oomycete pathogen lineages, the need for sustainable agriculture practices has become the need of the hour. The late blight of tomato caused by Phytopthora infestans, has recently emerged as one such devastating disease in India that led to huge crop losses. Hence, in the present work seed priming with mycogenic selenium nanoparticles (SeNPs) for elicitation of resistance against tomato late blight disease is investigated. It also aims to understand the defense responses triggered by SeNPs at cellular, biochemical and transcriptomic levels. Enhanced plant growth parameters were observed in bioactive SeNPs-primed tomato plants as compared to control plants. SeNPs-primed and pathogen inoculated plants exhibited a significant protection of 72.9 % against late blight disease. The primed plants also recorded a remarkable accumulation of lignin, callose and hydrogen peroxide that serve as the cellular defense over the control plants. Further, an elevated level of lipoxygenase (LOX), phenylalanine lyase (PAL), β-1,3-glucanase (GLU), superoxide dismutase (SOD) corroborated the biochemical defense in primed plants, which was also reflected in the corresponding transcriptome profiling of the genes encoding the enzymes. Thus, the present study represents an orchestrated correlation between resistance and defense responses incited by SeNPs against tomato late blight disease, which can be used as nano-biostimulant fungicide in protecting tomato plants.