Publications of NIPGR Scientists

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Author: search.filters.author.Ramegowda, VenkategowdaSubject: search.filters.subject.Combined stress

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    Stress combinations and their interactions in crop plants
    (Springer Nature Publishing AG, 2024) Ramegowda, Venkategowda; Senthil, Alagarswamy; Senthil‑Kumar, Muthappa
    Combined stresses are a common occurrence in agricultural felds. There is a pressing need for empirical understanding of the plant responses and fnd ways to develop stress tolerant plants and stress management strategies to tackle combined stresses in the feld conditions. Here a comprehensive overview of the current understating and recent research on combined stress interactions in plants are presented. Here we comprehend the fndings from various studies focusing on diferent aspects of combined stress, including abiotic-abiotic, abiotic-biotic, and biotic-biotic stress interactions. In general, the studies discussed here highlight the escalating impact of climate change on plants, emphasizing the need for a deeper understanding of plant responses to concurrent abiotic and biotic stresses. Key fndings from the articles published in this issue, include the adverse efects of combined drought and high-temperature stress on crop growth and yield, the exacerbation of pathogen impacts under abiotic stresses, and the potential for melatonin and salicylic acid to mitigate stress-induced damage. Additionally, use of model systems for quicker understanding of combined stress responses and development of methods and technologies which can be extrapolated to crop plants are discussed. Overall, fndings from the articles from this special issue underscore the complexity of combined stress interactions in plants and highlight the importance of interdisciplinary research eforts to address the challenges posed by climate change and ensure global food security.
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    Drought attenuates plant responses to multiple rhizospheric pathogens: A study on a dry root rot-associated disease complex in chickpea fields
    (Elsevier B.V., 2023) Chilakala, Aswin Reddy; Pandey, Prachi; Durgadevi, Athimoolam; Kandpal, Manu; Patil, Basavanagouda S.; Rangappa, Krishnappa; Reddy, Puli Chandra Obul; Ramegowda, Venkategowda; Senthil-Kumar, Muthappa
    Context or problem: Root rots, a major factor contributing to yield loss in chickpea, often occur in disease complexes. Objective or research question: Plant responses to disease complexes are not well elucidated. We sought a clear understanding of a newly identified disease complex in chickpea, dry root rot (DRR)–wilt disease complex, in the field and studied the effect of drought on the severity of the complex and its effect on yield. We compared plant responses to DRR alone and the disease complex under drought and determined the phytohormones involved in plant defense against the disease complex. Methods: We compared the effect of 14 environments (two soil moisture regimes at seven locations) on the incidence of the disease complex and yield loss in four chickpea genotypes. We also studied the effect of drought on rhizospheric and root endo-microbial communities by whole-genome and metagenomic sequencing and performed LC-MS-based phytohormonal profiling of chickpea roots. Results: Soil moisture and plant genetic variability were critical in modulating disease incidence in field conditions. DRR was the primary driver of the disease complex under drought stress. Drought aggravated the yield reductions caused by the disease complex from 35% to 60% in susceptible genotypes. Further, drought-tolerant genotypes performed better under combined disease complex infection and drought stress and exhibited lesser yield losses than susceptible genotypes. Pathogenic fungi such as Macrophomina phaseolina, Fusarium oxysporum, and Rhizoctonia solani were enriched in the chickpea rhizosphere, and M. phaseolina was predominant in infected chickpea roots under both well-watered and drought conditions. Symbiotic associations of chickpea with nitrogen-fixing bacteria were suppressed under drought stress. Abscisic acid, jasmonic acid, and salicylic acid were found to be involved in defense against the disease complex across various stages of plant growth. Implications or significance: We highlight the interaction between drought and soil pathogens affecting chickpea yield and suggest the utilization of drought-tolerant root traits as donor traits for improving combined stress resistance. We also demonstrate growth stage–dependent phytohormonal responses elicited by DRR and the DRR–wilt disease complex. The identification and management of root rots is essential, and our findings offer valuable new insights into a lesser-known but highly significant disease complex of chickpea. Data availability statement: Manuscript data is available at Supplementary File S1. The soil microbe whole-genome and metagenome and root-microbe 16 S and ITS sequencing data are available at NCBI PRJNA871091 and PRJNA895851.
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    Transcriptomic changes under combined drought and nonhost bacteria reveal novel and robust defenses in Arabidopsis thaliana
    (Elsevier B.V., 2017) Choudhary, Aanchal; Gupta, Aarti; Ramegowda, Venkategowda; Senthil-Kumar, Muthappa
    Plants in the natural conditions are often challenged by a combination of two or more stressors. A combination of drought and pathogen is one of the most pressing threats to the plant’s growth and survival in the field, and thus warrants a mechanistic understanding. Susceptible plant-pathogen interaction, owing to effector-mediated suppression of plant defense responses, limits its scope for combined stress studies. In the present study, we have investigated the morpho-physiological responses of Arabidopsis thaliana to simultaneous drought and nonhost bacterial pathogen Pseudomonas syringae pv. tabaci. Combined stress treatment provoked an early and more pronounced hypersensitive response in the plant as compared to the non-host pathogen treatment. We have further deciphered the molecular basis for the robust defense response observed under combined stress by transcriptomic profiling carried out using whole-genome microarray. We found that the enhanced resistance to the combined stress is accompanied by a massive transcriptional reprogramming involving several transcripts specifically responding to the stress combination. A prominent over-representation of genes involved in basal defense-related machinery was observed under the combined stress. Genes involved in various defense signaling cascades, accumulation of secondary metabolites and those encoding for receptor-like kinases were highly up-regulated under the combined stress. Up-regulated genes related to redox homeostasis and hypersensitive response (HR)-mediated cell death were also found to be markedly enriched under combined stress. We also compared the global gene expression profile of A. thaliana subjected to combined drought-nonhost bacteria to those treated with a combination of drought-host bacteria Pseudomonas syringae pv. tomato DC3000. A significant induction of genes responding to drought as well as bacteria was observed during both the interactions. However, the amplitude of induction was more pronounced under the combination of drought and nonhost bacteria. Our results also indicate that plant activates multiple defense pathways upon exposure to combined stress which strengthens the overall basal immunity of the plant, characterized by a stronger HR response.