Publications of NIPGR Scientists

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Author: search.filters.author.Senthil-Kumar, MuthappaSubject: search.filters.subject.Drought

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    Navigating towards dry root rot resistance in mungbean: impacts, mechanisms, and management strategies
    (Springer Nature Publishing AG, 2024) Sadhana, Nithyananth Hemanth; Geethanjali, Subramaniam; Mirchandani, Rishabh; Natesan, Senthil; Senthil-Kumar, Muthappa
    Vigna radiata L., commonly referred to as mungbean or green gram, holds significant importance as a pulse crop in India. However, its productivity is severely impacted by the combined incidence of dry root rot disease and drought stress. Dry root rot, caused by Macrophomina phaseolina, manifests as reduced yield and compromised produce quality. M. phaseolina is a necrotrophic fungus with a broad host range. Screening studies in several crops’ germplasms have shown a skewness towards susceptibility. Further, the fungus has augmented virulence and survivability in soil under low moisture and high heat. Thus, concurrent drought and dry root rot leads to significantly higher yield losses. This review highlights the status of the disease in mungbean and its future implications owing to the changing climate scenario. We also highlight the molecular and genomic studies conducted in mungbean and several other crops to elucidate the mechanisms involved in M. phaseolina resistance. The review also suggests management practices which can alleviate yield losses in dry root rot affected fields. Understanding the physiological and molecular mechanisms of dry root rot, drought, and their interaction on disease proliferation can help mitigate the challenges associated with dry root rot management and aid future research.
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    Abiotic stress impact on the interaction between Macrophomina phaseolina and crop plants
    (Springer Nature Publishing AG, 2024) Ranjan, Shubhashish; Mirchandani, Rishabh; Senthil-Kumar, Muthappa
    Macrophomina phaseolina (Tassi.) Goid is an emerging pathogen that causes diseases like dry root rot and charcoal rot in more than 100 plant families. Abiotic stresses such as drought, salinity, and heat exacerbate this fungal effect and predispose crops to pathogen attacks. Importantly, these combined stresses lead to significant crop yield losses under field conditions. In this, we review the interaction between the devastating pathogen M. phaseolina and several abiotic stresses that are more likely to occur in scenarios of climate change. Drought, heat, and salinity are the major stresses that interact with M. phaseolina in the field. We discuss several field studies, unique physiological and molecular responses, and their mechanisms of control in response to combined stress. The net effect of these interactions depends on a multitude of factors; thus, these interactions modify the impact of biotic stresses on plants by altering their susceptibility. The aim of this review is to provide an overview of what is currently known about M. phaseolina and abiotic stress interactions, as well as several other edaphic factors that interact with plants. We briefly discuss the role of drought, salinity, heat stress, and edaphic factors (such as pH, N, P, K, etc.) that influence pathogen infection in plants. Furthermore, we discuss possible management strategies to combat crop loss due to combined stress. Thus, we suggest the future aspect of combined stress breeding, along with the use of multi-omics techniques and genome editing approaches, to develop cultivars that exhibit stability in a combined stress environment.
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    Dry root rot disease: Current status and future implications for chickpea production
    (Springer Nature Publishing AG, 2023) Mirchandani, Rishabh; Irulappan, Vadivelmurugan; Chilakala, Aswin Reddy; Senthil-Kumar, Muthappa
    Chickpea is one of the most important food legumes in the world. Several abiotic and biotic factors limit chickpea yields, notably, heat, drought, and dry root rot (DRR) disease. The occurrence and severity of DRR are further magnified by abiotic stresses. This review highlights the current impact of DRR on chickpea production in India, the deepening of the economic losses caused by DRR owing to drought, and integrated management practices to curb DRR. Management strategies and research targeting this aspect are critical because the long-term consequences of this rapidly emerging disease could be severe owing to climate change.
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    Investigation of the novel transcriptional changes under combined drought and bacterial stress underpins the role of AtMYB96 in imparting tolerance
    (Springer Nature Publishing AG, 2021) Choudhary, Aanchal; Senthil-Kumar, Muthappa
    The physiological and molecular responses instigated to combat drought and bacterial pathogens often work antagonistically and, in most cases, the impact of combined stress is more detrimental to plant growth. Interestingly, plants exposed to this stress combination show a novel transcriptome fingerprint with a significant set of genes that are uniquely altered under combined stress. Despite this being reported in several transcriptomic datasets, our molecular understanding of these combined stress-specific genes and pathways is still in its nascent stages. These unique genes and the dedicated regulatory pathways are important for understanding the molecular aspects of signaling responses under combined stress. In this study, a previously available microarray dataset was extensively reanalysed to identify the novel genes and pathways specifically altered under combined stress. Using a combination of bioinformatic and data-guided approaches, we identified major biological pathways, transcription factor (TF) network and novel motifs potentially involved in the combined stress-specific responses. The candidate gene analysis using gene expression and mutant analysis identified AtMYB96 as an important TF involved in combined stress response. Taken together, our analysis pinpoints many novel genes that can be used for understanding the molecular mechanism of how plants deal with the combination of drought and bacterial pathogen.
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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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    Morpho-physiological traits and molecular intricacies associated with tolerance to combined drought and pathogen stress in plants
    (Springer Nature, 2018) Irulappan, Vadivelmurugan; Senthil-Kumar, Muthappa
    Crops in field conditions are challenged by the simultaneous occurrence of drought and pathogen stress. In the past, research was primarily focused on studying the impact of individual stresses on plants and selection of crop varieties potentially tolerant to particular stress by yield-associated morpho-physiological traits. However, several molecular responses of crop plants underlying morpho-physiological features to concurrent stresses are not similar to that of individual stresses. Certain morpho-physiological traits such as cell membrane stability, leaf water potential, stomatal movement, and root length were shown to be altered distinctly under combined stress to combat the stress condition. However, the relevance of such traits under combined stress tolerance is not precisely known. In this chapter, from the extensive literature survey, we identified several morpho-physiological changes that could be cognate with better plant performance under combined stress and represented them as traits that have potential to impart combined stress tolerance. We have comprehensively explained physiological and molecular basis for each trait and, where possible, suggested the ways to exploit the information for identification of varieties with prospective traits. Also, we proposed the need for systematically studying the underlying regulatory traits under combined stress conditions in the future.
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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.
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    Plant responses to combined drought and pathogen infection: current understanding on the role of phytohormones
    (Springer, 2017) Pandey, Prachi; Senthil-Kumar, Muthappa
    Plants under natural conditions encounter a number of abiotic and biotic stresses often being inflicted simultaneously. Plant responses to a stress are governed by intricate network of the hormone signaling pathways. Abscisic acid (ABA) forms the major component of the plant response to drought and cold stress. Salicylic acid (SA), jasmonic acid (JA), and ethylene act as key regulators of plant response to pathogen infection. In fact, the extensive cross talk among the different hormone-mediated signaling pathways determines plant response to a particular stress. A large number of studies focus on hormone signaling under individual drought and pathogen stresses and the cross talk between the two stress responses. However, owing to the relatively few studies on combined drought and pathogen stresses, our understanding of phytohormonal signaling under combined stress is still obscure. Recent studies on combined drought and pathogen infection indicate that plants when simultaneously exposed to the two stresses often exhibit a transcriptional and metabolic response different from that exhibited under single stress conditions. This is also applicable to the phytohormonal signaling. The nature, time, and severity of the two stresses in combination modulate hormonal concentrations as well as the hormone signal transduction pathways involved. In this chapter, we provide a compendious description of the role of the three major hormones, namely, ABA, SA, and JA, in combined drought and pathogen infection. A brief description of the role of auxins, cytokinins, and gibberellins has also been provided. Taking leads from few studies, we have discussed the potential role of hormones in conferring combined drought and pathogen stress tolerance to plants. We also briefly discussed the effect of different “stress elicitors” on hormone signaling.
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    Tissue water status and bacterial pathogen infection: how they are correlated?
    (Springer, 2017) Fatima, Urooj; Senthil-Kumar, Muthappa
    Tissue water status plays an important role in determining the fate of plant-pathogen interaction. Water availability is one of the factors that determine the multiplication of bacteria on the surface and inside the plants. Plant-water relations are highly influenced by soil water status, and drought stress is known to severely impact plant-pathogen interaction. Water, as a limiting factor, is differentially manipulated by both plants and pathogens during compatible and incompatible interactions. Plants stimulate the localized loss of water at the site of infection for limiting the bacterial multiplication. On the other hand, foliar and vascular bacterial pathogens employ different strategies to alter the plant water status and eventually establish the infection in plants. Foliar pathogens manipulate their own machinery in response to water-limited condition in plants. They also modulate the plant machinery in order to promote disease by increasing the water soaking between the cells. Similarly, vascular pathogens use different strategies such as clogging of vessels and embolism of xylem elements that leads to wilting of plant. Here, we discuss the current knowledge on impact of drought stress during plant interaction with foliar or vascular pathogen interactions.
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    The interactive effects of simultaneous biotic and abiotic stresses on plants: Mechanistic understanding from drought and pathogen combination
    (Elsevier B.V., 2015) Ramegowda, Venkategowda; Senthil-Kumar, Muthappa
    In nature, plants are simultaneously exposed to a combination of biotic and abiotic stresses that limit crop yields. Only recently, researchers have started understanding the molecular basis of combined biotic and abiotic stress interactions. Evidences suggest that under combined stress plants exhibit tailored physiological and molecular responses, in addition to several shared responses as part of their stress tolerance strategy. These tailored responses are suggested to occur only in plants exposed to simultaneous stresses and this information cannot be inferred from individual stress studies. In this review article, we provide update on the responses of plants to simultaneous biotic and abiotic stresses, in particular drought and pathogen. Simultaneous occurrence of drought and pathogen during plant growth provokes complex pathways controlled by different signaling events resulting in positive or negative impact of one stress over the other. Here, we summarize the effect of combined drought and pathogen infection on plants and highlight the tailored strategies adapted by plants. Besides, we enumerate the evidences from pathogen derived elicitors and ABA response studies for understanding simultaneous drought and pathogen tolerance.