Publications of NIPGR Scientists

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Author: search.filters.author.Gupta, AartiSubject: search.filters.subject.Drought

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    ath-miR164c influences plant responses to the combined stress of drought and bacterial infection by regulating proline metabolism
    (Elsevier B.V., 2020) Gupta, Aarti; Patil, Mahesh; Qamar, Aarzoo; Senthil-Kumar, Muthappa
    Plants under combined stresses exhibit a prominent shift in molecular responses compared with plants exposed to the same stresses independently. Profiling responses to individual and combined stressors at the gene expression level have identified several genes with intersecting responses to these stressors. However, the upstream regulators at the intersection of plant responses to individual and combined stresses are not known. Here, using the transcriptome of Arabidopsis thaliana under individual and combined drought and Pseudomonas syringae infection, we identified several genes whose expression overlaps between individual and combined stresses. To study the key regulator of such an overlapping gene, we predicted that the expression of 1-Pyrroline-5-carboxylate synthase 1 (AtP5CS1) is regulated by ath-miR164c at post-transcriptional level. Our results from the stem-loop RT-PCR based expression analysis revealed significant downregulation of ath-miR164c in response to P. syringae infection under both well-irrigated (pathogen only) and drought stress (combined stress) conditions. Furthermore, an Arabidopsis loss-of-function mutant of the miRNA ath-miR164c exhibited resistance to pathogen infection under combined stress, unlike the wild-type plants, implicating the role of ath-miR164c in regulating plant immunity. AtP5CS1 gene expression and proline accumulation were enhanced in the ath-miR164c mutant plants relative to the wild-type plants, demonstrating that ath-miR164c regulates AtP5CS1 of the proline biosynthesis pathway, which was also validated by 5’RLM-RACE results. This miRNA-mediated modulation of AtP5CS1 gene expression under combined stress fills crucial gaps in identifying the key convergent players in the current understanding of plant stress responses.
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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.