Publications of NIPGR Scientists
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Item A blotting paper technique for the screening of chickpea genotypes against dry root rot disease(Springer Nature Publishing AG, 2026) Durgadevi, Athimoolam; Pandey, Prachi; Senthil-Kumar, MuthappaDry root rot (DRR) disease is a major threat to chickpea production across the world. This disease is caused by a soil-borne necrotrophic fungal pathogen, Macrophomina phaseolina. The use of disease-resistant varieties paves the way to conquer the disease spread. Though chickpea germplasm with rich genetic diversity is available around the world, its response to DRR is still unexplored. In turn, this demands screening and identification of resistant genotypes for crop protection against the disease. Here we describe an improved blotting paper technique for the large-scale screening of chickpea genotypes for DRR resistance. The method is quick, cost-effective, less labour-intensive, and thus optimized for high-throughput screening and can be efficiently used to screen a large number of chickpea genotypes for resistance against DRR.Item Extracellular acidification assay to evaluate the effectiveness of antifungal agents on the pathogenicity of Macrophomina phaseolina(Springer Nature Publishing AG, 2026) Acharya, Krishna Ramakrishnan; Chilakala, Aswin Reddy; Senthil-Kumar, MuthappaMacrophomina phaseolina is a fungus that causes dry root rot disease and considerable yield loss worldwide. Fungi exhibit various ways of absorbing nutrients through their plasma membrane, such as free or facilitated diffusion, diffusion channels, or active transport. Glucose, as a preferred carbon source, activates the plasma membrane H+-ATPase, resulting in the release of protons. Consequently, the protons, along with the organic acid metabolites released into the extracellular environment, acidify the cell surroundings. This decrease in pH cues the fungus to shift from saprotrophic to necrotrophic growth, facilitating host invasion. Sustainable dry root rot disease management often relies on the employment of antifungal agents from various biological sources. Despite the discovery of numerous antifungal agents, only a limited number have been evaluated for their efficacy against this phytopathogenic fungus. This scarcity of testing is primarily due to the limitations of existing methods, which often lack standardisation and reproducibility. This chapter introduces a rapid and sensitive method to assess the antifungal activity of various agents against M. phaseolina. By measuring extracellular pH changes after treatment in the presence of a nutrient source, we can determine the inhibitory concentrations of these agents and evaluate their potential for controlling fungal pathogenicity in plants.Item Induced post-invasive defenses in the nonhost plant Parthenium hysterophorus L. prevent root cortical colonization by Macrophomina phaseolina and impart resistance to dry root rot(Elsevier B.V., 2025) Mirchandani, Rishabh; Kandpal, Manu; Ranjan, Aashish; Sinharoy, Senjuti; Senthil-Kumar, MuthappaDry root rot (DRR) of chickpea is caused by the broad-range necrotrophic fungus Macrophomina phaseolina. Chickpea germplasm does not provide durable resistance to DRR, which is particularly devastating under drought. Even moderately resistant chickpea varieties become susceptible under combined stress. We hypothesized that nonhost resistance (NHR) is durable even under combined stress. Using the blotter paper assay and stereomicroscopic observations, we identified the asterid weed Parthenium hysterophorus as a potential nonhost of M. phaseolina among 82 potential nonhosts. Epidermal necrotic lesions were prevented in P. hysterophorus. In planta fungal load was 0.195 and 0.007 ng/ng total DNA in chickpea and P. hysterophorus, respectively. M. phaseolina could not colonize the P. hysterophorus root while up to 6 cortical cell layers were colonized in chickpea. Further, NHR was durable under combined stress. Dual RNA sequencing revealed that M. phaseolina actively attempted to infect the nonhost and activated specific genes in the xenobiotics degradation pathway. P. hysterophorus also showed an active defense response with1958 and 2294 differentially expressed genes at 2 and 4 DAI, respectively, with 363 upregulated at both time points. Differential expression of cell wall synthesis, phytohormone signaling, and other defense response pathways likely contributes to NHR. Few genes in the phenylpropanoid biosynthesis pathways in P. hysterophorus were also upregulated, possibly because these metabolites are linked to the distinct changes in the fungus during nonhost infection. We therefore conclude that P. hysterophorus exhibits post-invasive NHR to M. phaseolina and that general defense, phytohormone signaling and secondary metabolic pathways contribute to NHR.Item 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, MuthappaVigna 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.Item MicroRNA397 regulates tolerance to drought and fungal infection by regulating lignin deposition in chickpea root(John Wiley & Sons, 2023) Sharma, Nilesh Kumar; Yadav, Shalini; Gupta, Santosh Kumar; Irulappan, Vadivelmurugan; Francis, Aleena; Senthil-Kumar, Muthappa; Chattopadhyay, DebasisPlants deposit lignin in the secondary cell wall as a common response to drought and pathogen attacks. Cell wall localised multicopper oxidase family enzymes LACCASES (LACs) catalyse the formation of monolignol radicals and facilitate lignin formation. We show an upregulation of the expression of several LAC genes and a downregulation of microRNA397 (CamiR397) in response to natural drought in chickpea roots. CamiR397 was found to target LAC4 and LAC17L out of twenty annotated LACs in chickpea. CamiR397 and its target genes are expressed in the root. Overexpression of CamiR397 reduced expression of LAC4 and LAC17L and lignin deposition in chickpea root xylem causing reduction in xylem wall thickness. Downregulation of CamiR397 activity by expressing a short tandem target mimic (STTM397) construct increased root lignin deposition in chickpea. CamiR397-overexpressing and STTM397 chickpea lines showed sensitivity and tolerance, respectively, towards natural drought. Infection with a fungal pathogen Macrophomina phaseolina, responsible for dry root rot (DRR) disease in chickpea, induced local lignin deposition and LAC gene expression. CamiR397-overexpressing and STTM397 chickpea lines showed more sensitivity and tolerance, respectively, to DRR. Our results demonstrated the regulatory role of CamiR397 in root lignification during drought and DRR in an agriculturally important crop chickpea.Item 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, MuthappaChickpea 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.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 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.