Udai B. Singh

Bio-protective microbial agents from rhizosphere eco-systems trigger plant defense responses provide protection against sheath blight disease in rice (Oryza sativa L.).

Sheath blight of rice (Oryza sativa L.) caused by Rhizoctonia solani is a major disease and attempts are being made to develop microbe based technologies for biocontrol of this pathogen. However, the mechanisms of biocontrol are not fully understood and still require indepth study in the backdrop of emerging concepts in biological systems. The present investigation was aimed at deciphering the mechanisms of biocontrol of sheath blight of rice employing Pseudomonas fluorescens and Trichoderma harzianum as model agents for biocontrol. Initially 25, 5 and 5 strains of P. fluorescens, T. viride and T. harzianum, respectively, were screened for their biocontrol potential. Out of which, six strains with higher value of percent inhibition of fungal mycelium in dual plate assay were selected. The role of P. fluorescens, T. viride and T. harzianum were investigated in induction and bioaccumulation of natural antioxidants, defence-related biomolecules and other changes in plant which lead not only to growth promotion but also protection from pathogenic stress conditions in rice. The two most promising strains, P. fluorescens PF-08 and T. harzianum UBSTH-501 selected on the basis of in planta evaluation, when applied individually or in combination, significantly enhanced the accumulation of defence-related biomolecules, enzymes and exhibited biocontrol potential against R. solani. A modified/newly developed delivery system was applied for the first time in the experiments involving inoculation of plants with both bioagents, viz. P. fluorescens PF-08 and T. harzianum UBSTH-501. Results suggested that application of P. fluorescens PF-08 and T. harzianum UBSTH-501 alone or in combination, not only helps in control of the disease but also increases plant growth along with reduction in application of toxic chemical pesticides.

Role of Plant Growth-Promoting Rhizobacteria for Improving Crop Productivity in Sustainable Agriculture

The plant growth-promoting rhizobacteria (or PGPR) are the beneficial microorganism that colonizes rhizosphere and help in promoting plant growth, protecting from biotic and abiotic stresses, and significantly increasing soil fertility. For the effective ways of developing sustainable agriculture for improving crop productivity with a minimal disturbance to the environment is the exploration of plant growth-promoting rhizobacteria and some other microbe-based symbioses in plants. For increasing crop yields, the use of PGPR has been well proven for its eco-friendly sound by promoting plant growth either direct or indirect mechanism. The mechanisms of plant growth-promoting rhizobacteria include resistance against plant pathogens, solubilizing nutrients for easy uptake, and maintaining the plant growth regulator hormone. This chapter emphasizes an eco-friendly approach to increase crop production and health, the development of sustainable agriculture, the mechanism of PGPR for agricultural sustainability, and the role in different major crop plant varieties along with their mechanism of action.

Microbial Cultures: Maintenance, Preservation and Registration

Microorganisms account for major biomass on the Earth and play an important role in biogeochemical processes that are important for survival of all forms of life on this planet. In this context, the conservation of microbial communities and their ecosystem should be given high priority. Microbiologists have always thought of preservation of culturable microbial diversity in adequate manner without changes in morphological, physiological, and genetic traits. Culture collections (ex situ conservation), also known as microbial resource centres (MRCs), have made huge contributions in storage and preservation of all kinds of microorganisms. In this chapter, we have discussed ex situ preservation methods of microorganisms followed in National Agriculturally Important Microbial Culture Collection (NAIMCC) and other culture collections across the world. Four international culture collections and seventeen (17) national culture collections having either status of International Depository Authority (IDA) or National Biodiversity Authority (NBA) or both have been discussed in this chapter. This chapter also highlights short-, medium-, and long- term methods used for the preservation of microorganisms along with some latest techniques such as Sordelli’s method, vitrification, and encapsulation. Some critical factors that affect the cell survival and recovery during the process of preservation have also been incorporated. In general, description of NAIMCC with its infrastructure and activities including registration of elite microbial germplasm has been highlighted for benefits of researchers, farmers, and industries of India and abroad.

Earthworm Grazed-Trichoderma harzianum Biofortified Spent Mushroom Substrates Modulate Accumulation of Natural Antioxidants and Bio-Fortification of Mineral Nutrients in Tomato

The present investigation was aimed at evaluating the impact of earthworm grazed and Trichoderma harzianum biofortified spent mushroom substrate (SMS) on natural antioxidant and nutritional properties of tomato. Results of the investigation reveal that earthworm grazing and T. harzianum bio-fortification led to significant improvement in the physico-chemical properties of fresh SMS and its application increased the accumulation of natural antioxidants and mineral content in tomato as compared to either T. harzianum biofortified SMS or fresh SMS. In particular, the earthworm grazed, T. harzianum biofortified SMS (EGTHB-SMS) was found to inhibit lipid peroxidation and protein oxidation with significant increase in total polyphenol and flavonoid content in tomato. Further, it increased Fe2+/Fe3+ chelating activity, superoxide anion radical scavenging activity compared to other treatments. The results thus suggest an augmented elicitation of natural antioxidant properties in tomato treated with EGTHB-SMS, resulting in a higher radical scavenging activity, that is highly desirable for human health. In addition, the use of SMS to enhance the nutritional value of tomato fruits becomes an environment friendly approach in sustainable crop production.

Novel insight into the molecular interaction of catalase and sucrose: A combination of in silico and in planta assays study

Abstract Osmolytes are known to be an important factor for the stabilization and proficient functioning of proteins. However, the stabilization mechanism of proteins by the interaction of osmolytes is still not well explored. Here, we performed in silico 3D structure modelling of rice catalase-A (CatA) protein and its molecular interaction with sucrose. Further, in planta was conducted to see the effects of sucrose on catalase activity in rice grown in saline sodic soil at different time intervals. The molecular docking experiments results showed that sucrose can be ligated with CatA, protein forming hydrogen bond with precise amino acid residues like, R49, R89, P309, F311, Y335 and T338. The interaction also comprises the contribution of hydrophobic amino acid residues like V50, V51, H52, L123, A310, Q339 and R342. The planta in vitro catalase activity assay showed that plants treated with sucrose significantly affect the catalase activity in rice. Results revealed that maximum catalase activity was recorded in plants treated with 150 and 200 ppm of sucrose after 15 days of sucrose application. However, minimum activity was recorded in control plants. We believe that our study will provides an advanced understanding of catalase activity in plants exposed to osmotic stress.

National Agriculturally Important Microbial Culture Collection in the Global Context of Microbial Culture Collection Centres

Understanding the metabolic and evolutionary patterns of microorganisms has played a pivotal role in the development of agriculture, industry and health sectors. Therefore, for the ex situ conservation of the microbial diversity, microbial culture collections also known as Biobanks or Microbial Resource Centres remain the most important scientific infrastructure. This review describes the history and evolution of microbial culture collections and the growth of the global community of collections through the activities of the World Federation for Culture Collections (WFCC). In addition, it highlights the roles of culture collections in assisting research and development including the role of an International Depository Authority recognized under Budapest Treaty. Furthermore, the status of microbial culture collections available in India with emphasis on collection of agriculturally important microbes has been investigated. National Agriculturally Important Microbial Culture Collection is a designated national repository established at the Indian Council of Agricultural Research–National Bureau of Agriculturally Important Microorganisms, Maunath, Bhanjan, Uttar Pradesh, India in 2004 and is an affiliate member of WFCC (WDCM-1060) which currently encompasses over 6000 well characterized strains of bacteria, cyanobacteria, fungi etc. The deposited microorganisms are being used as bioinoculants, biopesticides and for management of soil fertility, biotic and abiotic stresses in crops for sustainable production.

Microbe-Mediated Biotic Stress Management in Plants

Biotic stress factors have a major impact on plants and cause extensive losses to crop production. Plants possess a range of defenses that can be actively expressed in response to pathogens. The timely activation of these defense responses is important and determines whether plant is able to cope or succumb to the challenge of a pathogen. Plant defense mechanisms which are involved in biotic stress management are classified as innate and induced plant response. Systemic acquired resistance (SAR) and induced systemic resistance (ISR) are two forms of induced resistance; in both types of resistance, prior infection or treatment preconditions plant defenses leading to resistance (or tolerance) against further challenge by a pathogen. Identification of a number of biological and chemical elicitors has to a great extent helped in unraveling the understanding of the biochemical and physiological basis of ISR and SAR. Combining SAR and ISR can provide protection against a number of pathogens including the pathogens that resist through both pathways. The use of pesticides for the control of crop diseases and pests is however inefficient and not eco-friendly. Genetic engineering has enabled the cloning of genes and their insertion into the crop plants to make them resistant to different biotic stresses.