Browsing by Author "Suman Bakshi"

Now showing 1 - 3 of 3

A Klebsiella rhizobacterium deregulates the metabolism of phytopathogenic Aspergillus flavus during in-vitro assays and confers protective functions
(Elsevier B.V., 2024) Shree P. Pandey; Shivam Singh; Deepesh Khandwal; Avinash Mishra; Bhagya Shree Acharya; Suman Bakshi; Sundeep Kumar; Vinod Mishra; Sandeep Sharma
In previous investigations, we have identified a rhizobacterium (Klebsiella sp. MBE02) that confers host protection against several phytopathogenic fungi. For instance, this rhizobacterium prevents Aspergillus flavus infection and promotes peanut growth and fitness in controlled and field-conditions. The mechanistic basis of the protective function offered by this rhizobacterium is not completely understood. MBE02 directly restricts the growth of the pathogenic fungi, which led us to hypothesize that it may strongly dysregulate the metabolism of A. flavus, and inhibit critical metabolic processes of the fungus, which severely restricts pathogen growth. We have tested this hypothesis by using untargeted metabolite profiling. Sixty-nine A. flavus metabolites accumulated differentially due to the presence of the MBE02. MBE02 could inhibit several important metabolic pathways, which include the biosynthesis of critical primary metabolites such as amino acids and fatty acids. It also impacts energy metabolism of the fungus, and that the accumulation of several structural components, including of the cell wall, were strongly inhibited. MBE02 abrogated the accumulation of disease-causing metabolites in A. flavus, whereas the accumulation of metabolites that inhibit fungal growth were enhanced. On the other hand, A. flavus did not strikingly impact the accumulation of metabolites of the MBE02. Our investigation supports the hypothesis that Klebsiella sp. MBE02 mediates protective function by directly impairing the pathogen's metabolism. © 2024 The Authors
Expression analysis of hormonal pathways and defense associated genes in gamma-rays mutagenized wheat genotypes against combined stresses of spot blotch and terminal heat
(Elsevier B.V., 2022) G Mahendra Singh; SrinathaReddy S; Gaurav Sharma; Suman Bakshi; Uttam Kumar; Pradeep Bhati; Sanjay J. Jambhulkar; Ramesh Chand; Arun K. Joshi; Vinod K. Mishra; Sandeep Sharma
Wheat (Tritium aestivum L.) productivity is severely hampered by various pathogens and changing climatic conditions. Spot blotch and terminal heat stress are the major constraints of wheat production in the eastern Gangetic plains of India. To identify novel breeding sources and to understand underlying resistance mechanisms, forty-four gamma rays mutagenized wheat genotypes, derived from three different parents were screened under favourable agro-ecological conditions for spot blotch and terminal heat stress. Ten mutants showed reduced spot blotch infection calculated based on Area Under Disease Progress Curve (AUDPC), than their respective parents. The mutant TAW41 had the least infection (AUDPC: 354.32), significantly lower than its parent HD2967 (AUDPC: 675.51) and other checks. TAW41 also had a higher Normalized Difference Vegetation Index (NDVI) and chlorophyll content than the parent. Gene expression analysis of TAW41 showed differential accumulation of transcripts involved in hormonal pathways (Salicylic acid, Jasmonic acid, and ethylene) and other defense-associated genes, indicating that TAW41 might have unique resistance mechanism that facilitates this genotype to perform better against the combined stress of spot blotch and terminal heat. Hence, mutant TAW41 has been identified as a novel source of resistance that could be exploited in wheat improvement programmes to enhance tolerance to spot blotch and terminal heat stress. © 2021 The Authors
Transcriptional response of cultivated peanut (Arachis hypogaea L.) roots to salt stress and the role of DNA methylation
(Springer Science and Business Media Deutschland GmbH, 2025) Shree Prakash Pandey; Chen Chen; Shivam Singh; Jalak N. Maniar; Avinash Mishra; Suman Bakshi; Vinod Kumar Mishra; Sandeep K. Sharma
Key message: Our study unravels a complex multi-layered molecular response of peanut roots to salinity, where reprograming of gene-expression is partly executed by changes in methylome via RdDM pathway and exerted through transcription factors. Abstract: Peanut (Arachis hypogaea L.) is a major oilseed crop of global importance, whose production is severely impacted by salinity. Here, we have explored the transcriptional response of peanut roots to salinity stress using deep sequencing. Further, we have unravelled the salinity-induced changes in peanut root methylome. When peanut seedlings were grown under high-salt conditions for 7 days, their root and shoot growth was significantly impaired. A large-scale transcriptional reprogramming was recorded where 1926 genes were down- and 3260 genes were up-regulated due to salt stress in peanut roots. The molecular response of peanut root comprised several layers of regulators, which included the genes related to ion transport, osmolyte accumulation, signal transduction, and salt stress-responsive genes. Several negative regulators are also differentially expressed in peanut roots, which may contribute to its susceptibility. This response is regulated by a large number of transcription factors (TFs) and epigenetically by changes in DNA methylation. The DNA methylation changes in roots were highly complex and context dependent when exposed to salt stress. An inverse relationship between the changes in gene expression and methylation status was partially observed for several important gene sets and TFs. A treatment with 5’-azacytidine recovered the inhibitory impact of salt stress in peanut roots. Thus, a complex multilayered molecular response to salinity in peanut roots was observed. A part of this response may be modulated by the reprogramming of RNA-directed DNA methylation pathway. This investigation also serves as a resource for future gene-mining and methylation studies for improving peanut resistance to salt stress. © The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature 2025.