Publications of NIPGR Scientists
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Item From combined stress to climate resilience: harnessing the power of a knowledge resource(Current Science Association, 2024) Maitraya, Bharat; Pandey, Prachi; Senthil-Kumar, MuthappaUnderstanding the intricate dynamic impact of combined stresses on plant growth and productivity amidst escalating climate change is one of the most prevalent challenges for today’s plant stress biologists. This commentary emphasizes the necessity of employing a centralized resource to collect and analyse scattered data on combined and individual abiotic and biotic stresses in plants. Introducing the Stress Combinations and their Interactions in Plants Database, we underscore its role in consolidating and comprehending diverse omics datasets and facilitating interdisciplinary research efforts to advance agricultural research.Item When two negatives make a positive: The favorable impact of the combination of abiotic stress and pathogen infection on plants(Oxford University Press, 2024) Pandey, Prachi; Patil, Mahesh; Priya, Piyush; Senthil-Kumar, MuthappaCombined abiotic and biotic stresses modify plant defense signaling, leading to either the activation or suppression of defense responses. Although the majority of combined abiotic and biotic stresses reduce plant fitness, certain abiotic stresses reduce the severity of pathogen infection in plants. Remarkably, certain pathogens also improve the tolerance of some plants to a few abiotic stresses. While considerable research focuses on the detrimental impact of combined stresses on plants, the upside of combined stress remains hidden. This review succinctly discusses the interactions between abiotic stresses and pathogen infection that benefit plant fitness. Here, we discuss various factors that govern the positive influence of combined abiotic stress and pathogen infection on plant performance. We also provide a brief overview of the role of pathogens, mainly viruses, in improving plant responses to abiotic stresses. We further highlight the critical nodes in defense signaling that guide plant responses during abiotic stress towards enhanced resistance to pathogens. Studies on antagonistic interactions between abiotic and biotic stressors can uncover candidates in host plant defense that may shield plants from combined stresses.Item Combined drought and heat stress influences the root water relation and determine the dry root rot disease development under field conditions: A study using contrasting chickpea genotypes(Frontiers Media S.A., 2022) Chilakala, Aswin Reddy; Mali, Komal Vitthalrao; Irulappan, Vadivelmurugan; Patil, Basavanagouda S.; Pandey, Prachi; Rangappa, Krishnappa; Ramegowda, Venkategowda; Kumar, M. Nagaraj; Puli, Chandra Obul Reddy; Mohan-Raju, Basavaiah; Senthil-Kumar, MuthappaAbiotic stressors such as drought and heat predispose chickpea plants to pathogens of key importance leading to significant crop loss under field conditions. In this study, we have investigated the influence of drought and high temperature on the incidence and severity of dry root rot disease (caused by Macrophomina phaseolina) in chickpea, under extensive on- and off-season field trials and greenhouse conditions. We explored the association between drought tolerance and dry root rot resistance in two chickpea genotypes, ICC 4958 and JG 62, with contrasting resistance to dry root rot. In addition, we extensively analyzed various patho-morphological and root architecture traits altered by combined stresses under field and greenhouse conditions in these genotypes. We further observed the role of edaphic factors in dry root rot incidence under field conditions. Altogether, our results suggest a strong negative correlation between the plant water relations and dry root rot severity in chickpeas, indicating an association between drought tolerance and dry root rot resistance. Additionally, the significant role of heat stress in altering the dynamics of dry root rot and the importance of combinatorial screening of chickpea germplasm for dry root rot resistance, drought, and heat stress have been revealed.Item Drought stress exacerbates fungal colonization and endodermal invasion and dampens defense responses to increase dry root rot in chickpea(American Phytopathological Society, 2022) Irulappan, Vadivelmurugan; Kandpal, Manu; Saini, Kumud; Rai, Avanish; Ranjan, Aashish; Sinharoy, Senjuti; Senthil-Kumar, MuthappaDrought plays a central role in increasing the incidence and severity of dry root rot (DRR) disease in chickpea. This is an economically devastating disease, compromising chickpea yields particularly severely in recent years due to erratic rainfall patterns. Macrophomina phaseolina (formerly Rhizoctonia bataticola) is the causal agent of DRR disease in the chickpea plant. The infection pattern in chickpea roots under well-watered conditions and drought stress are poorly understood at present. This study provides detailed disease symptomatology and the characteristics of DRR fungus at morphological and molecular levels. Using microscopy techniques, the infection pattern of DRR fungus in susceptible chickpea roots was investigated under well-watered and drought stress conditions. Our observations suggested that drought stress intensifies the progression of already ongoing infection by weakening the endodermal barrier and overall defense. Transcriptomic analysis suggested that the plant’s innate immune defense program is downregulated in infected roots when subjected to drought stress. Further, genes involved in hormonal regulation are differentially expressed under drought stress. These findings provide hints in terms of potential chickpea genes to target in crop improvement programs to develop climate change-resilient cultivars.Item Drought attenuates plant defence against bacterial pathogens by suppressing the expression of CBP60g/SARD1 during combined stress(John Wiley & Sons, 2022) Choudhary, Aanchal; Senthil-Kumar, MuthappaIn nature, plants are frequently exposed to drought and bacterial pathogens simultaneously. However, information on how the drought and defence pathways interact and orchestrate global transcriptional regulation is limited. Here, we show that moderate drought stress enhances the susceptibility of Arabidopsis thaliana to Pseudomonas syringae pv. tomato DC3000. Using transcriptome meta-analysis, we found that drought and bacterial stress antagonistically modulate a large set of genes predominantly involved in salicylic acid (SA) and abscisic acid (ABA) signalling networks. We identified that the levels of SA and ABA are dynamically regulated during the course of stress. Importantly, under combined stress, drought through the ABA pathway downregulates the induction of CALMODULIN-BINDING PROTEIN 60g (CBP60g) and SYSTEMIC ACQUIRED RESISTANCE DEFICIENT 1 (SARD1), two transcription factors crucial for SA production upon bacterial infection. We also identified an important role of NPR1-LIKE PROTEIN 3 and 4 (NPR3/4) transcriptional repressors in the drought-mediated negative regulation of CBP60g/SARD1 expression. Using a genetic approach, we show that CBP60g/SARD1 expression is the key determinant of plant defence against bacterial pathogens under combined stress. Thus, these transcription factors act as critical nodes for the crosstalk between drought and bacterial stress signalling under combined stress in plants.Item Progress and prospects of concurrent or combined stress studies in plants(John Wiley & Sons, 2021) Mahalingam, Ramamurthy; Pandey, Prachi; Senthil-Kumar, MuthappaPlants growing under field conditions are often exposed to multiple abiotic and biotic stresses occurring simultaneously or sequentially. Biotic stressors often interact with abiotic stressors at the plant interphase, which makes the impact of their combination on plants remarkably variable, though differing with order and intensity of stresses, as well as plant species and pathotypes. In this article, we examine the major abiotic stress combinations, as well as abiotic-biotic stress combinations, and physiological and molecular responses of plants to these combined stresses. Utilizing the available literature, information on the phenomic and transcriptomic response of plants to the combined abiotic and biotic stresses, and the cross-talk during signalling is reviewed. A succinct discussion on the scope and application of combined abiotic and biotic stress studies highlighting major gaps and novel avenues for further research is articulated.Item Dry root rot of chickpea: A disease favored by drought(American Phytopathological Society, 2022) Rai, Avanish; Irulappan, Vadivelmurugan; Senthil-Kumar, MuthappaChickpea is an essential crop for protein nutrition and is grown around the world in rain-fed conditions. However, chickpea cultivation is under threat due to emerging diseases favored by drought stress. Dry root rot (DRR), an economically devastating disease, is an example. Chickpea-specific strains of a necrotic fungal phytopathogen, Macrophomina phaseolina, cause DRR. Microsclerotia of this fungus, which are capable of withstanding harsh environmental conditions, serve as primary inoculum. Initial symptoms are scattered necrotic spots in roots, progressing to rotting and withering lateral roots, accompanied by prematurely dried, straw-colored foliage. The recent rise in global temperature and worsening of drought spells have aggravated DRR outbreaks in chickpea. To date, DRR epidemiology has not been clarified in detail. Also, the literature lacks clarity on M. phaseolina taxonomy, morphology, disease progression, and diagnosis. In this article, research progress on patterns of DRR occurrence in the field and belowground and above-ground symptoms are clarified. In addition, the current understanding of taxonomy and management practices is elaborated. We also summarize knowledge of the impact of drought and high temperature on DRR severity. Further, we provide future perspectives on the importance of host resistance, QTL identification, genotype screening for the identification of resistant genotypes. The article proposes new research priorities and a corresponding plan for the mitigation of DRR.Item A sick plot-based protocol for dry root rot disease assessment in field-grown chickpea plants(John Wiley & Sons, 2021) Irulappan, Vadivelmurugan; Mali, Komal Vitthalrao; Patil, Basavanagouda S.; Manjunatha, Hanumappa; Muhammad, Saifulla; Senthil-Kumar, MuthappaPremise: A comprehensive field-based screening protocol is lacking for dry root rot (DRR) disease in chickpea, which is caused by Macrophomina phaseolina (formerly referred to as Rhizoctonia bataticola). Here, we describe a protocol for establishing a sick plot for DRR to enable disease assessment of a large number of chickpea plants during the natural growing season. Methods and Results: We used a chickpea plot with >30% DRR incidence, and enriched the inoculum by cultivating highly susceptible chickpea plant genotypes and incorporating infected plant material into the soil. The chickpea plants were then subjected to infection in developed sick plots with various levels of soil moisture under natural field conditions. Conclusions: Our protocol provides a robust way to impose M. phaseolina infection on chickpea plants under natural field conditions and to investigate plant responses to the infection at morphological, physiological, and molecular levels. This method can also be used to screen for other soil‐borne diseases in a variety of plants.Item Role of plant kinases in combined stress(John Wiley & Sons, 2021) Patil, Mahesh; Senthil-Kumar, MuthappaPlants in nature are exposed to multiple stresses during their life cycle, affecting growth and productivity. Plants have evolved various molecular mechanisms to cope with stress by altering the protein and enzyme activity involved in cellular processes. Protein phosphorylation, catalyzed by kinase, is one of the critical regulatory mechanisms known to control protein and enzyme activity and its interaction with other proteins involved in the cellular signaling cascade. In eukaryotes, approximately 1–3% of functional genes encode protein kinases, implicating the relevance of kinases in cellular regulation and metabolism. Several past studies have shown the importance of protein phosphorylation by kinases under different stresses like drought, heat, high light, pathogen attack, and nutrient deprivation. However, the role of kinases under combined stresses has been elucidated for only a few. In this chapter, using publically available microarray data under combined stress, we have identified the protein kinases involved in different abiotic and biotic stress combinations. Further, an attempt has also been made to explain the possible function of the identified kinases through literature analysis and also to emphasize the need for functional validation of these kinases under combined stress for a better understanding of the stress tolerance mechanisms.Item An efficient, high-throughput method for the simultaneous exposure of drought stress and bacterial infection in plants(John Wiley & Sons, 2020) Choudhary, Aanchal; Senthil-Kumar, MuthappaPREMISE: We developed a systematic protocol for the easy, high-throughput, qualitative, and quantitative assessment of the patho-morphological, physiological, and molecular responses of Arabidopsis thaliana plants simultaneously subjected to drought and bacterial infection. This approach will assist studies elucidating plant adaptation strategies to combat combined stresses. METHODS AND RESULTS: Plants were grown in small screw-capped containers, individual pots, or pot strips. Watering was withheld from 30-day-old plants, which were subsequently infected with Pseudomonas syringae pv. tomato DC3000 using a dip inoculation. The natural development of both drought and bacterial infection was successfully and rapidly replicated in large numbers of plants, which is difficult to achieve with existing protocols. CONCLUSIONS: Our protocol offers a simple, low-cost, high-throughput strategy for the rapid and easy bacterial infection of large numbers of plants. It can be used in large-scale mutant and ecotype screenings under combined stresses and for other foliar pathogens in different plant species.