The ability for rhizobacteria and fungus to act as bioprotectants via induced systemic resistance has been demonstrated, and considerable progress has been made in elucidating the mechanisms of ...plant–biocontrol agent–pathogen interactions. Pseudomonas aeruginosa PJHU15, Trichoderma harzianum TNHU27, and Bacillus subtilis BHHU100 from rhizospheric soils were used singly and in consortium and assessed on the basis of their ability to provide disease protection by relating changes in ascorbic acid and hydrogen peroxide (H₂O₂) production, lipid peroxidation, and antioxidant enzymes in pea under the challenge of Sclerotinia sclerotiorum. Increased production of H₂O₂ 24 h after pathogen challenge was observed and was 254.4 and 231.7–287.7 % higher in the triple consortium and singly treated plants, respectively, when compared to untreated challenged control plants. A similar increase in ascorbic acid content and ascorbate peroxidase activity was observed 24 and 48 h after pathogen challenge, respectively, whereas increased activities of catalase, guaiacol peroxidase, and glutathione peroxidase were observed 72 h after pathogen challenge. Similarly, lipid peroxidation reached a maximum at 72 h of pathogen challenge and was 61.2 and 11.2–32.1 % less in the triple consortium and singly treated plants, respectively, when compared to untreated challenged control plants. These findings suggest that the interaction of microorganisms in the rhizosphere enhanced protection from oxidative stress generated by pathogen attack through induction of antioxidant enzymes and improved reactive oxygen species management.
Sclerotium rolfsii is a highly aggressive pathogen that causes huge economic losses, especially in temperate climates. Alcaligenes faecalis, particularly in endophytic form, has rarely been used to ...control this fungus. In this study, endophytic Alcaligenes sp. strain BHU 12, BHU 16 (isolated from Abelmoschus esculentus leaf) and BHU M7 (isolated from Andrographis paniculata leaf) were reported to trigger a wide range of host defenses in Okra plant against the collar-rot pathogen S. rolfsii. Endophytic colonization of the strains in ten days old plants was assessed through re-isolation of the rif-tagged strains on rifampicin augmented nutrient agar media. The ability of the endophytic strains to induce systemic defense responses in above-ground organs was assessed by collecting leaf tissues of the Okra plants grown under non-gnotobiotic conditions at different time intervals post seedling bacterization with the endophytic biocontrol agents. The pathogen challenged unprimed plants exhibited flaccidity of the stem and leaves at 48 h post infection (hpi) in contrast to the bioprimed and challenged plants. Biochemical and histochemical analyses explained the above phenomenon as activation of phyto-peroxidases leading to an increased metabolism of the reactive oxygen species (ROS), accompanied by activation of the phenylpropanoid network and a subsequent enhancement in plant phenolics. Interestingly, though the maximum increase in the defense pathways was observed in treatments with native endophytes of Okra plant, yet the enhancement in antioxidant pathway due to A. paniculata borne endophytes was also quite significant. Thus, this work clearly demonstrates how Okra plants respond to the “non-hostile” colonization of bacterial endophytes and how induced defense response can contribute to the biocontrol activity of the endophytic strains.
•Prominent H2O2 accumulation and minimal O2− production in infected control in contrast to the endophyte primed hosts.•Prominent augmentation of antioxidant enzymes and phenylpropanoid pathway in endophytic bacteria primed Okra plants.•Magnification of ascorbate-glutathione pathway in primed and infected treatments as compared to infected control.•Reduced lipid peroxidation and cell death in endophytic bacteria primed Okra plants in contrast to infected control.
Seed dormancy represents a pivotal challenge in seed germination, standing as a significant impediment to attaining SDG 2 - the zero-hunger goal. This dormancy arises from a range of environmental ...stressors, including restricted water conditions, temperature fluctuations, and light exposure. Consequently, the disruption of seed dormancy assumes paramount importance to ensure consistent germination and the cultivation of high-quality crops. Seed priming, an approach involving the treatment and desiccation of seeds, serves to augment pre-germination metabolism and expedite the germination process. Traditional priming methods encompass hydro-priming, halo-priming, hormonal-priming, and osmo-priming, each contributing to enhanced seed germination. Recent strides in priming technology have yielded even more effective outcomes concerning germination, germination timing, and seedling vigor. Novel approaches such as nano-priming (employing nanoparticle-infused solutions) and magneto-priming (involving magnetic fields) have surfaced, fostering uniform seed germination. Preeminent among these strategies is seed bio-priming, which not only alleviates seed dormancy but also augments nutrient uptake efficiency in germinating seedlings. This review paper delineates diverse priming methodologies applicable across a spectrum of crops, serving as an environmentally benign alternative to mitigate dormancy-linked predicaments and enhance plant growth. Additionally, we delve into the latest advancements in priming techniques and offer future perspectives. The central objective of this review article is to enhance comprehension of seed priming as a potent and invaluable tool for surmounting seed dormancy, consequently fostering sustainable global food production.
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•Seed dormancy is a major constraint in ‘Zero hunger goal’.•Urgency to induce seed germination rate under climate change conditions.•Seed priming is an effective tool to overcome dormancy problem.•Seed-biopriming and nano-priming showed most prominent results.•Priming techniques can be used in sustainable agriculture practices.
Sclerotium rolfsii is a broad host necrotrophic pathogen causing serious damages in crop yields. Apart from chemical fungicides being used to control this pathogen, no bio-fungicides have been ...reported till date. In this study, we have tried to utilize heat killed S. rolfsii hyphae for triggering biosynthesis of antifungal compounds in the endophytic bacterium Alcaligenes faecalis BHU 12. The endophytic bacterial cell free supernatant (CFS) obtained by growing BHU 12 in presence of freeze-crushed and autoclaved S. rolfsii hyphae caused prominent S. rolfsii hyphal degeneration and inhibition of sclerotial germination under in vitro conditions. This result was further corroborated under in planta conditions wherein spraying of the CFS at the point of infection inhibited further pathogen ingress. This observation was justified by the presence of gallic and shikimic acid in the CFS which served as antifungal agent and augmentor of plant defense system respectively. Infected plants sprayed with the CFS were found to display a prominent increase in phenylalanine ammonia lyase activity and a corresponding increase in total phenolics. In this context, our results described the possible alternative of using endophytic bacterial metabolite compounds as biofungicides. A simultaneous augmentation in seed germination upon treatment with the CFS suggests a possibility of using endophytic bacterial supernatants as biocontrol and biofertilizer alternative instead of whole bacterial cell since indigenous soil microbiota combined with cumbersome inoculation techniques prevents successful colonization of endophytic microbes in planta.
•Killed S. rolfsii induces production of antifungal products in A. faecalis extract.•The extract causes hyphal and sclerotial damage under in vitro conditions.•Prominent inhibition of S. rolfsii growth in planta treated with A. faecalis extract.•Upregulation of plant defense enzymes upon treatment with A. faecalis extract.
Phenolics play a key role in communication between plants and microbes in the rhizosphere. In this study, shikimic, gallic, fumaric, ferulic, vanillic acid and quercetin in root exudates of ...Abelmoschus esculentus act as chemoattractants of endophytic Alcaligenes faecalis strains, BHU 12, BHU 16 and BHU M7. In vitro chemotaxis assay showed that BHU 12 expressed highest chemotactic movement (CFU ∼50×1012) towards A.esculentus root exudates followed by BHU 16 and BHU M7 (CFU∼ 9×1012), thereby confirming their ability to colonize the host rhizoplane region. However, BHU 16 expressed highest biofilm formation ability followed by BHU 12 and BHU M7. Assessment of chemotactic and biofilm formation potential towards individual phenolic acids revealed BHU 12 to be maximally attracted towards 1μM shikimic acid (2×1015) while BHU 16 towards 1mM vanillic acid (6.5×1012) and BHU M7 towards 1mM ferulic acid (3.5×1012), thereby confirming the phenolic acid components responsible for particularly attracting the endophytic isolates. Upon colonization, the endophytic isolates modified the phenolic profiles of root exudates in planta in a manner so as to plausibly attract more of the beneficial rhizospheric microbiota as well as self-fortification against pathogenic microbes. This hypothesis was verified by monitoring the changes in phenolic components of A. esculentus root exudate owing to S. rolfsii infection, a disastrous soil-borne pathogen. Thus, on the whole, the work provides intricate details of plant-endophyte interactions for biotic stress management through careful manipulation of root exudates, thereby aiding in sustainable agriculture.
The science of nanotechnology, the manipulation, design and engineering of devices at the atomic and molecular scale, is starting to be applied to many disciplines including aspects of agriculture ...and crop science. This book opens with a brief history of nanotechnology in agriculture. Applications are then examined in detail, including nanopesticides, nanosensors, nanofertilizers, and nanoherbicides. Topics covered include; the biosynthesis of nanoparticles (through microbes, plants and other biotic agents); the ecological consequences of their delivery into the environment (examining effects and toxicity on soil, soil biota, and plants); safety issues; an overview of the global market for nanotechnology products, and the regulation of nanotechnology in agriculture. The book concludes with speculations on what the future holds for the technology.The book has been written by an international group of researchers and experts from over 12 countries with experience across a wide range of issues relating to the industry.This book will be of use to a wide range of researchers and professional scientists in the agricultural sector, academia and industry, including microbiologists, chemical engineers, geneticists, plant scientists and biochemists.
Trichoderma spp. have been reported to aid in imparting biotic as well as abiotic tolerance to plants. However, there are only few reports unfolding the differential ability of separate species of ...Trichoderma genera generally exploited for their biocontrol potential in this framework. A study was undertaken to evaluate the biocontrol potential of different Trichoderma species namely T. harzianum, T. asperellum, T. koningiopsis, T. longibrachiatum, and T. aureoviride as identified in the group of indigenous isolates from the agricultural soils of Eastern Uttar Pradesh, India. Their biocontrol potential against three major soilborne phytopathogens, i.e., Sclerotium rolfsii, Sclerotinia sclerotiorum, and Colletotrichum capsici was confirmed by dual culture plate technique. Efficient mycoparasitic ability was further assessed in all the isolates in relation to chitinase, β‐1,3 glucanase, pectinase, lipase, amylase, and cellulase production while equally consistent results were obtained for their probable phosphate solubilization and indole acetic acid (IAA) production abilities. The selected isolates were further subjected to test their ability to promote plant growth, to reduce disease incidence and to tolerate biotic stress in terms of lignification pattern against S. rolfsii in chickpea plants. Among the identified Trichoderma species, excellent results were observed for T. harzianum and T. koningiopsis indicating better biocontrol potential of these species in the group and thus exhibiting perspective for their commercial exploitation.
Biocontrol strategies have been mainly focused on proposing the use of biocontrol agents (BCAs) isolated from the rhizospheric region of the plant for protection against phytopathogens. The present ...study evaluates the effectiveness of phyllospheric
Trichoderma
isolates in elevating the defense responses in chilli against
Colletotrichum
capsici
infection and comparing its efficiency to the conventionally recommended rhizospheric
Trichoderma
strains. The elicitation of the defense network in the plants was analyzed using biochemical assays for important enzymes, that is, PAL, PO, PPO, TPC, SOD along with the total protein level in challenged plants over untreated and unchallenged control plants. The results recorded 2.1, 5.18, 3, 0.67, and 0.5-fold increases in TPC, PAL, PO, PPO, and total protein content in BHUF4 (phyllopsheric
Trichoderma
isolate)-treated plants when compared to control plants under
C. capsici
challenge. This was at par with the increment recorded in T16A (rhizospheric
Trichoderma
isolate)-treated chilli plants. The increment in growth parameters was also recorded after treatment with the isolated
Trichoderma
strains. Interestingly, the phyllospheric isolate (BHUF4) treatment recorded comparable growth promotion in chilli plants recording 36, 62, and 60 % increases in one of the major parameters of plant growth, that is, root length, no. of leaves, and dry weight, respectively. This study proposes the use of combined application of both rhizospheric as well as phyllospheric
Trichoderma
isolates for better and all around protection of plants against foliar as well as soil phytopathogens. This would be a novel approach in biological control strategy for better management of anthracnose disease of chilli.
The present study was carried out with the aim of evaluating the effectiveness and potentiality of three compatible rhizosphere microbes, viz., fluorescent Pseudomonas aeruginosa (PHU094), ...Trichoderma harzianum (THU0816) and Mesorhizobium sp. (RL091), in promoting plant growth and mobilizing phenolic acid biosynthesis in chickpea under challenge of Sclerotium rolfsii. The microbes were applied as seed coating in different combinations in two experimental sets and the pathogen was inoculated after 25 days of sowing in one set. Results revealed that microbe application led to higher growth in chickpea particularly in the triple microbe combination compared to their individual treatments and control. Similarly, pathogen challenged plants accumulated higher amount of phenolic compounds both at the site of attack of the pathogen i.e. collar region as well as leaves compared to unchallenged plants. All the bioagents were found to trigger the level of phenolic compounds at collar region in varying degrees as compared to the healthy control (A). However, the most effective treatment was D7 (combined application of PHU094, THU0816 and RL091 with pathogen challenge) among all the treatments. Shikimic acid was maximally induced amongst all the phenolic compounds. In leaves also, the most effective treatment was D7 where shikimic acid, t-chlorogenic acid, ferulic acid, myricetin, quercetin and syringic acid were produced in higher amounts as compared to treatment B where the plants were challenged only with the pathogen.
The beneficial plant‐microbe interactions play crucial roles in protection against large number of plant pathogens causing disease. The present study aims to investigate the growth promoting traits ...induced by beneficial microbes namely Pseudomonas aeruginosa PJHU15, Trichoderma harzianum TNHU27, and Bacillus subtilis BHHU100 treated singly and in combinations under greenhouse and field conditions to control Sclerotinia sclerotiorum. Plants treated with three microbe consortium enhanced plant growth maximally both in the presence and absence of the pathogen. Increase in plant length, total biomass, number of leaves, nodules and secondary roots, total chlorophyll and carotenoid content, and yield were recorded in plants treated with microbial consortia. Also, a decrease in plant mortality was observed in plants treated with microbial consortia in comparison to untreated control plants challenged with S. sclerotiorum. Furthermore, the decrease in disease of all the treatments can be associated with differential improvement of growth induced in pea.
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