Browsing by Author "Pawan K. Sharma"

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Inter-Genera Colonization of Ocimum tenuiflorum Endophytes in Tomato and Their Complementary Effects on Na+/K+ Balance, Oxidative Stress Regulation, and Root Architecture Under Elevated Soil Salinity
(Frontiers Media S.A., 2021) Pramod K. Sahu; Shailendra Singh; Udai B. Singh; Hillol Chakdar; Pawan K. Sharma; Birinchi K. Sarma; Basavaraj Teli; Raina Bajpai; Arpan Bhowmik; Harsh V. Singh; Anil K. Saxena
Endophytic bacilli of ethano-botanical plant Ocimum tenuiflorum were screened for salt stress-alleviating traits in tomato. Four promising O. tenuiflorum endophytes (Bacillus safensis BTL5, Bacillus haynesii GTR8, Bacillus paralicheniformis GTR11, and Bacillus altitudinis GTS16) were used in this study. Confocal scanning laser microscopic studies revealed the inter-genera colonization of O. tenuiflorum endophytes in tomato plants, giving insights for widening the applicability of potential endophytes to other crops. Furthermore, in a pot trial under 150 mM NaCl concentration, the inoculated endophytes contributed in reducing salt toxicity and improving recovery from salt-induced oxidative stress by different mechanisms. Reduction in reactive oxygen species (ROS) (sub-cellular H2O2 and superoxide) accumulation was observed besides lowering programmed cell death and increasing chlorophyll content. Endophyte inoculation supplemented the plant antioxidant enzyme system via the modulation of enzymatic antioxidants, viz., peroxidase, ascorbate peroxidase, superoxide dismutase, and catalase, apart from increasing proline and total phenolics. Antioxidants like proline have dual roles of antioxidants and osmoregulation, which might also have contributed to improved water relation under elevated salinity. Root architecture, viz., root length, projection area, surface area, average diameter, tips, forks, crossings, and the number of links, was improved upon inoculation, indicating healthy root growth and enhanced nutrient flow and water homeostasis. Regulation of Na+/K+ balance and water homeostasis in the plants were also evident from the modulation in the expression of abiotic stress-responsive genes, viz., LKT1, NHX1, SOS1, LePIP2, SlERF16, and SlWRKY39. Shoot tissues staining with light-excitable Na+ indicator Sodium GreenTM Tetra (tetramethylammonium) salt showed low sodium transport and accumulation in endophyte-inoculated plants. All four endophytes exhibited different mechanisms for stress alleviation and indicated complementary effects on plant growth. Furthermore, this could be harnessed in the form of a consortium for salt stress alleviation. The present study established inter-genera colonization of O. tenuiflorum endophytes in tomato and revealed its potential in maintaining Na+/K+ balance, reducing ROS, and improving root architecture under elevated salinity. © Copyright © 2021 Sahu, Singh, Singh, Chakdar, Sharma, Sarma, Teli, Bajpai, Bhowmik, Singh and Saxena.
Microbial Interactions in the Rhizosphere Contributing Crop Resilience to Biotic and Abiotic Stresses
(Springer, 2020) Deepti Malviya; Udai B. Singh; Shailendra Singh; Pramod K. Sahu; K. Pandiyan; Abhijeet S. Kashyap; Nazia Manzar; Pawan K. Sharma; H.V. Singh; Jai P. Rai; Sushil K. Sharma
Rhizosphere is a hot spot where specific kinds of diverse microbial communities develop under the influence of exudates from plant roots and in turn modulate growth and development of the plant. Such communities with or without interactions perform an array of functions, including nitrogen fixation, P, Zn, Si and K-solubilization, siderophore production, ammonification, hormones production, ACC deaminase production, ethylene production, anammox, comammox, nitrification, denitrification, antagonisms, induce resistance to plant, C-sequestration, volatile production, secondary metabolites production and many others that are known to modulate soil and plant health contributing to the corresponding responses to various stresses of biotic and abiotic nature. The magnitude of resilience of plant to biotic and abiotic stresses is completely dependent on types of communities and their interactions. With enhanced knowledge and understanding about rhizosphere, researchers are evaluating various approaches to engineer rhizosphere in such way that it enables plant to enhance the productivity and sustain it while maintaining soil health. This chapter highlights detailed account of microbial interactions in the rhizosphere with associated mechanisms that contribute to resilience of plants to stress for better growth and development. © Springer Nature Singapore Pte Ltd. 2020.
Modulation in Biofertilization and Biofortification of Wheat Crop by Inoculation of Zinc-Solubilizing Rhizobacteria
(Frontiers Media S.A., 2022) Ramesh Chandra Yadav; Sushil K. Sharma; Ajit Varma; Mahendra Vikram Singh Rajawat; Mohammad Shavez Khan; Pawan K. Sharma; Deepti Malviya; Udai B. Singh; Jai P. Rai; Anil K. Saxena
Zinc is an important micronutrient needed for the optimum growth and development of plants. Contrary to chemical zinc fertilizers, the use of zinc-solubilizing bacteria is an environmentally friendly option for zinc enrichment in edible parts of crops. This study was conducted with the objective of selecting potential zinc-solubilizing rhizobacteria from the rhizosphere of chickpea grown in soils of eastern Uttar Pradesh and further assessing their impact on the magnitude of zinc assimilation in wheat crops. Among 15 isolates, CRS-9, CRS-17, CRS-30, and CRS-38 produced net soluble zinc in broth to the tune of 6.1, 5.9, 5.63, and 5.6 μg ml–1, respectively, in zinc phosphate with the corresponding pH of 4.48, 5.31, 5.2, and 4.76. However, the bacterial strains CRS-17, CRS-30, CRS-38, and CRS-9 showed maximum zinc phosphate solubilization efficiency of 427.79, 317.39, 253.57, and 237.04%, respectively. The four bacterial isolates were identified as Bacillus glycinifermentans CRS-9, Microbacterium oxydans CRS-17, Paenarthrobacter nicotinovorans CRS-30, and Bacillus tequilensis CRS-38 on the basis of morphological and biochemical studies and 16S rRNA gene sequencing. Bacterial inoculants significantly colonized the roots of wheat plants and formed a biofilm in the root matrix. These strains significantly increased seed germination (%) and vigor indices in wheat grown under glasshouse conditions. After 30 days of sowing of wheat under microcosm conditions, eight zinc transporter (TaZIP) genes were expressed maximally in roots, with concomitant accumulation of higher zinc content in the bacterially treated plant compared to the absolute control. Out of the four strains tested, two bacteria, B. tequilensis CRS-38 and P. nicotinovorans CRS-30, improved seed germination (%), vigor indices (2–2.5 folds), plant biomass, grain yield (2.39 g plant–1), and biofortificated grains (54.25 μg g–1Zn) of wheat. To the best of our knowledge, this may be the first report on the presence of zinc solubilization trait in B. glycinifermentans CRS-9, M. oxydans CRS-17, and P. nicotinovorans CRS-30. Copyright © 2022 Yadav, Sharma, Varma, Rajawat, Khan, Sharma, Malviya, Singh, Rai and Saxena.
Novel benzenesulfonamide bearing 1,2,4-triazoles as potent anti-microbial and anti-oxidant agents
(Springer, 2023) Chander; Monika; Akhilesh Kumar; Deepansh Sharma; Pawan K. Sharma; Sita Ram
A series comprising 30 novel benzenesulfonamide bearing 1,2,4-triazoles 1a–1h, 2a–2h, 3a–3h, 4b–4f and 4h has been synthesized and investigated as anti-microbial and anti-oxidant agents. All the tested compounds exhibited moderate to excellent inhibitory potential against tested Gram-positive (Staphylococcus aureus ATCC 6538P, Listeria monocytogenes MTCC 657, and Bacillus cereus ATCC 11770) and Gram-negative (Pseudomonas aeruginosa ATCC 15442, Escherichia coli MTCC 143, Salmonella typhi MTCC 733, Shigella flexneri ATCC 9199) bacterial strains with minimum inhibitory concentration values ranging from 3.12 to 12.5 µg/mL. Compound 3d was either equipotent or better inhibitor than reference drugs against all tested bacterial as well as fungal strains. All the tested compounds were also found to be safe to normal cells with 89.8–99.8% cell viability against mouse fibroblast cell line and 100% safe to plant seed germination. Final compounds were also screened for their anti-oxidant profile using DPPH method and compound 4d was found to possess highest anti-oxidant acitivity (94.35%). Graphical Abstract: [Figure not available: see fulltext.] © 2023, The Author(s), under exclusive licence to Springer Science+Business Media, LLC, part of Springer Nature.
Zinc-solubilizing Bacillus spp. in conjunction with chemical fertilizers enhance growth, yield, nutrient content, and zinc biofortification in wheat crop
(Frontiers Media SA, 2023) Ramesh Chandra Yadav; Sushil K. Sharma; Ajit Varma; Udai B. Singh; Adarsh Kumar; Ingudam Bhupenchandra; Jai P. Rai; Pawan K. Sharma; Harsh V. Singh
Micronutrient deficiency is a serious health issue in resource-poor human populations worldwide, which is responsible for the death of millions of women and underage children in most developing countries. Zinc (Zn) malnutrition in middle- and lower-class families is rampant when daily calorie intake of staple cereals contains extremely low concentrations of micronutrients, especially Zn and Fe. Looking at the importance of the problem, the present investigation aimed to enhance the growth, yield, nutrient status, and biofortification of wheat crop by inoculation of native zinc-solubilizing Bacillus spp. in conjunction with soil-applied fertilizers (NPK) and zinc phosphate in saline soil. In this study, 175 bacterial isolates were recovered from the rhizosphere of wheat grown in the eastern parts of the Indo-Gangetic Plain of India. These isolates were further screened for Zn solubilization potential using sparingly insoluble zinc carbonate (ZnCO3), zinc oxide (ZnO), and zinc phosphate {Zn3(PO4)2} as a source of Zn under in vitro conditions. Of 175 bacterial isolates, 42 were found to solubilize either one or two or all the three insoluble Zn compounds, and subsequently, these isolates were identified based on 16S rRNA gene sequences. Based on zone halo diameter, solubilization efficiency, and amount of solubilized zinc, six potential bacterial strains, i.e., Bacillus altitudinis AJW-3, B. subtilis ABW-30, B. megaterium CHW-22, B. licheniformis MJW-38, Brevibacillus borstelensis CHW-2, and B. xiamenensis BLW-7, were further shortlisted for pot- and field-level evaluation in wheat crop. The results of the present investigation clearly indicated that these inoculants not only increase plant growth but also enhance the yield and yield attributes. Furthermore, bacterial inoculation also enhanced available nutrients and microbial activity in the wheat rhizosphere under pot experiments. It was observed that the application of B. megaterium CHW-22 significantly increased the Zn content in wheat straw and grains along with other nutrients (N, P, K, Fe, Cu, and Mn) followed by B. licheniformis MJW-38 as compared to other inoculants. By and large, similar observations were recorded under field conditions. Interestingly, when comparing the nutrient use efficiency (NUE) of wheat, bacterial inoculants showed their potential in enhancing the NUE in a greater way, which was further confirmed by correlation and principal component analyses. This study apparently provides evidence of Zn biofortification in wheat upon bacterial inoculation in conjunction with chemical fertilizers and zinc phosphate in degraded soil under both nethouse and field conditions. Copyright © 2023 Yadav, Sharma, Varma, Singh, Kumar, Bhupenchandra, Rai, Sharma and Singh.