Jai Singh Patel

The Molecular Mechanisms of KSMs for Enhancement of Crop Production Under Organic Farming

The continuous use of chemical fertilizers and pesticides for the enhancement of crop yield and instant action of pest control causes harmful and hazardous effect on the environment due to the accumulation of minerals and biomagnifications at higher hierarchical level. Therefore, the current need is alternative and eco-friendly technology as integrated pest management (IPM) and plant growth-promoting microorganisms (PGPMs) for enhancing organic farming practices. One of the promising microorganisms is potassium-solubilizing microorganisms (KSMs) as PGPMs are applicable for sustainable agriculture. Plant growth promotion (PGP) is a complex phenomenon rarely attributable to a single mechanism as most PGP microbes influence plant growth through multiple mechanisms. However, any microbial agent added to the rhizosphere has to interact not only with the plant but also with other organisms around the microenvironment. The KSMs have the ability for IAA production, K solubilization, antifungal, HCN, and siderophore production. Due to secretion of organic acids, KSMs solubilize various forms of K in soil to available forms which helps enhance plant growth, yield, and fertility status of soil. This book chapter is a critical summary of the efforts of scientist in efficient use of KSMs, mechanism of K solubilization, and use of these microorganisms for increasing the crop production. They also help plant to combat against pathogenic microbes and other environmental stresses. The indigenous microbes proven their effectiveness; such microbes suit the environmental conditions in the cropping system for which they are intended. This chapter covers the studies of KSMs, their sources, mechanism of K solubilization, and their effect on crops.

Pseudomonas fluorescens and Trichoderma asperellum Enhance Expression of Gα Subunits of the Pea Heterotrimeric G-protein during Erysiphe pisi Infection

We investigated the transcript accumulation patterns of all three subunits of heterotrimeric G-proteins (Gα1 and 2, Gβ, and Gγ) in pea under stimulation of two soil-inhabiting rhizosphere microbes Pseudomonas fluorescens OKC and Trichoderma asperellum T42. The microbes were either applied individually or co-inoculated and the transcript accumulation patterns were also investigated after challenging the same plants with a fungal biotrophic pathogen Erysiphe pisi. We observed that mostly the transcripts of Gα 1 and 2 subunits were accumulated when the plants were treated with the microbes (OKC and T42) either individually or co-inoculated. However, transcript accumulations of Gα subunits were highest in the T42 treatment particularly under the challenge of the biotroph. Transcript accumulations of the other two subunits Gβ and Gγ were either basal or even lower than the basal level. There was an indication for involvement of JA-mediated pathway in the same situations as activation of LOX1 and COI1 were relatively enhanced in the microbe co-inoculated treatments. Non-increment of SA content as well as transcripts of SA-dependent PR1 suggested non-activation of the SA-mediated signal transduction in the interaction of pea with E. pisi under the stimuli of OKC and T42. Gα1 and 2 transcript accumulations were further correlated with peroxidases activities, H2O2 generation and accumulation in ABA in pea leaves under OKC and T42 stimulations and all these activities were positively correlated with stomata closure at early stage of the biotroph challenge. The microbe-induced physiological responses in pea leaves finally led to reduced E. pisi development particularly in OKC and T42 co-inoculated plants. We conclude that OKC and T42 pretreatment stimulate transcript accumulations of the Gα1 and Gα2 subunits of the heterotrimeric G protein, peroxidases activities and phenol accumulation in pea during infection by E. pisi. The signal transduction was possibly mediated through JA in pea under the stimulus of the microbes and the cumulative effect of the co-inoculated microbes had a suppressive effect on E. pisi conidial development on pea leaves.

Plant genotype, microbial recruitment and nutritional security

Agricultural food products with high nutritional value should always be preferred over food products with low nutritional value. Efforts are being made to increase nutritional value of food by incorporating dietary supplements to the food products. The same is more desirous if the nutritional value of food is increased under natural environmental conditions especially in agricultural farms. Fragmented researches have demonstrated possibilities in achieving the same. The rhizosphere is vital in this regard for not only health and nutritional status of plants but also for the microorganisms colonizing the rhizosphere. Remarkably robust composition of plant microbiome with respect to other soil environments clearly suggests the role of a plant host in discriminating its colonizers (Zancarini et al., 2012). A large number of biotic and abiotic factors are believed to manipulate the microbial communities in the rhizosphere. However, plant genotype has proven to be the key in giving the final shape of the rhizosphere microbiome (Berendsen et al., 2012; Marques et al., 2014).

Molecular Mechanisms of Interactions of Trichoderma with other Fungal Species

Trichoderma species are known globally mostly for the production of industrially useful enzymes as well as their biocontrol ability against plant pathogens. One of the major strategies of biological control is mycoparasitism against fungal pathogens of crop plants. However, till recently the mechanisms of mycoparasitism by biocontrol potential Trichoderma species at molecular level were not clearly understood. The biochemical signaling and the involvement of secondary metabolites that lead to mycoparasitic activities of Trichoderma, in particular, were not very clearly known earlier. Recent findings in this regard revealed that there are a number of signaling cascades activated during the process of mycoparasitism by Trichoderma species against phytopathogenic fungal pathogens. In addition Trichoderma also interacts with beneficial root inhabiting fungi like mycorrhizae. The interaction of Trichoderma species with mycorrhizal fungi is different as during interaction with mycorrhizal fungi different signaling cascades are activated that lead to a synergistic action. In the current review, we gathered updated evidences regarding the signaling cascades that are generated during interactions between Trichoderma species with fungal pathogens resulting mycoparasitism as well as interactions of Trichoderma species with mycorrhizal fungi resulting synergism at molecular level. We also highlighted the role of secondary metabolites that are reported to be associated in the signaling processes.

The Indian Himalayan Ecosystem as Source for Survival

The Indian Himalayan Region (IHR) covers ~95 districts of the Indian union, which starts from the foothills in the south (Siwalik); the region extends to the Tibetan Plateau in the north (trans-Himalaya). The IHR occupies the strategic position of the entire northern boundary (northwest to northeast) of the country and touches almost all the international borders of seven countries with India. The contribution of India is ~16 % of total geographical area, out of which ~17 % area is under permanent snow cover and ~35 % is under seasonal snow cover. The IHR is responsible for providing water to a large part of the Indian subcontinent and contains varied flora and fauna; it was estimated that ~40 million of the population reside in this region. The Indian Himalayan rivers run off ~1,600,000 million m 3 of water annually for drinking, irrigation, hydropower, etc. The IHR has been a potential source of important medicinal herbs and shrubs. This region is extremely rich in plant life and abounds in genetic diversity of all types of fauna and flora. The medicinal virtues of the northwest (NW) Himalayan plants are well known from the early times of the great epics of Ramayana and Mahabharata and are mentioned in the oldest Hindu scriptures, viz., Rigveda, which is said to be the source of the Ayurvedic medicine system. These high hills are the storehouse of numerous herbs and shrubs, which are exploited not only for the pharmaceutical industries worldwide. In fact, a large percentage of crude drugs in the Indian market come from this Himalayan region. Besides this, the Himalayan regions remain as a source of many cereal crops, pulses, vegetables, fruits, and animal husbandry. The climate change impact is at a global level, and this Himalayan region is no exception. Due to the climatic changes, a lot of disturbances happening like flooding, drought, wildfire, and other global changes derive from pollutions and overexploitation of resources. These changes drastically degrade our natural resources, and nowadays it challenges a need to adopt a comprehensive master plan for conservation of these resources for the survival in the future.

Trichoderma asperellum (T42) and Pseudomonas fluorescens (OKC)-Enhances Resistance of Pea against Erysiphe pisi through Enhanced ROS Generation and Lignifications

Plant signaling mechanisms are not completely understood in plant–fungal biotrophic pathogen interactions. Further how such interactions are influenced by compatible rhizosphere microbes are also not well-studied. Therefore, we explored the pea-Erysiphe pisi (obligate biotroph) system to understand the interaction and applied compatible rhizospheric bio-agents Trichoderma asperellum (T42) and Pseudomonas fluorescens (OKC) singly or in combination to assess their influence on the host while under the pathogen challenge. Transcript accumulation pattern of some vital genes in the lignin biosynthetic pathway in pea under E. pisi challenge indicated enhanced activation of the pathway. Interestingly, transcript accumulations were even higher in the bio-agent treated plants compared to untreated plants after pathogen inoculation particularly in co-inoculated treatments. Further, down regulation of the lignifications-associated ABC transporter gene in the pathogen challenged plants possibly is an indication of passive diffusion of monolignols across the membrane from symplast. Additionally, up regulation of NADPH oxidase gene revealed ROS generation in the challenged plants which was confirmed through spectrophotometric estimation of H2O2. Up regulation of laccase and peroxidase along with higher H2O2 generation points out their involvement in lignifications which was further confirmed through cross section analysis of pea stems that showed increased lignifications in pathogen challenged plants co-inoculated with the bioagents. Interestingly, pathogen responsive MAPK homologs MAPK3/MAPK6 and the enzyme serine threonine kinase that activates MAPKs were down regulated and the results possibly indicate non-participation of the MAPK cascade in this interaction. Therefore, it can be concluded that the microbial treatments enhanced pea resistance to E. pisi by generation of ROS and lignifications.

Cellulase in Pulp and Paper Industry

The paper and packaging industry is an important part of the global economy and plays a critical role in the world economy. Cellulase, a complex enzyme produced by a number of microorganisms, has tremendous potential application in the pulp and paper industry. Cellulase contributes 10% of the worldwide industrial enzyme demand, and there is tremendous potential for cellulase biotechnology in pulp and paper manufacturing to grow steadily commercially, and to give rise to new possibilities. Cellulase, xylanase, laccase, and lipase are the most important enzymes that can be used in the pulp and paper processes. This prospective study aims to enhance the understanding of the most important advanced uses of cellulases for providing benefits to the pulp and paper industry in various areas like increased pulp yield, improved fiber properties, enhanced paper recycling, reduced processing and environmental problems, and energy efficiency.

Rhizospheric Microbes for Sustainable Agriculture: An Overview

Agriculture is a complex network interaction among soil-plant-microbes. There is an urgent need for an ecologically compatible, environment-friendly technique in agriculture system that might be able to provide adequate supply of essential nutrients for the alarming growing rate of human populations through qualitative and quantitative improvement of agricultural products. Conventional agriculture plays a crucial role to fulfill the increasing food demands of a growing human population, which has also led to enhancing the use of pesticides and chemical fertilizers. Improvement in agricultural sustainability requires optimal use and management of soil fertility which rely on soil microbiological processes and soil biodiversity. An understanding of microbial diversity perspectives in agriculture is important and useful to arrive at measures that can act as indicators of soil quality, soil health, and plant productivity. In this context, microorganisms present in soils have multiple plant growth-promoting (PGP) activities such as IAA (indole-3-acetic acid), hydrogen cyanide (HCN) and siderophore production, ACC deaminase activity, and nitrogen fixation and nutrient solubilization (P, K, and Zn). Efficient plant growth-promoting microorganisms (PGPMs) solubilize the nutrients in soil and facilitate absorption by plants and consequently enhance the plant growth and yield. PGPMs also sustain the soil fertility, soil health, and nutrient mobilization efficiency under sustainable agriculture.

Trichoderma mediate early and enhanced lignifications in chickpea during Fusarium oxysporum f. sp. ciceris infection

Lignifications in secondary cell walls play a significant role in defense mechanisms of plants against the invading pathogens. In the present study, we investigated Trichoderma strain specific lignifications in chickpea plants pre‐treated with 10 potential Trichoderma strains and subsequently challenged with the wilt pathogen Fusarium oxysporum f. sp. ciceris (Foc). Trichoderma‐induced lignifications in chickpea were observed through histochemical staining and expression of some genes of the lignin biosynthetic pathway. Lignifications were observed in transverse sections of shoots near the soil line through histochemical staining and expression pattern of the target genes was observed in root tissues through semi quantitative RT‐PCR at different time intervals after inoculation of F. oxysporum f. sp. ciceris. Lignin deposition and expression pattern of the target genes were variable in each treatment. Lignifications were enhanced in all 10 Trichoderma strain treated and F. oxysporum f. sp. ciceris challenged chickpea plants. However, four Trichoderma strains viz., T‐42, MV‐41, DFL, and RO, triggered significantly high lignifications compared to the other six strains. Time course studies showed that effective Trichoderma isolates induced lignifications very early compared to the other strains and the process of lignifications nearly completes within 6 days of pathogen challenge. Thus, from the results it can be concluded that effective Trichoderma strains trigger lignifications very early in chickpea under Foc challenge and provide better protection to chickpea plants.