Browsing by Author "Mahawar, Shivangi"

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Cellular responses in the pigeonpea wild relative Cajanus platycarpus to Helicoverpa armigera herbivory: The role of methionine sulfoxide reductase B1 (CpMSRB1) in enhanced defense
(American Phytopathological Society, 2025) Rathinam, Maniraj; Dokka, Narasimham; Senthil, Kameshwaran; Mahawar, Shivangi; Tyagi, Shaily; Rengarajan, Dineshkumar; Vijayaraghavareddy, Preethi; Iyyappan, Yuvaraj; YB, Basavaraj; Reddy, Sandeep; T, Vinutha; G, Rama Prashat; Sinha, Subodh Kumar; Dash, Prasanta K.; Sreeman, Sheshshayee; Majee, Manoj; Sreevathsa, Rohini
Understanding key cellular mechanisms leading to improved defense against various stressors is essential for cultivating robust nutritious crops capable of flourishing in diverse environments. We present an in-depth characterization of the defense response in the pigeonpea wild relative Cajanus platycarpus to herbivory by pod borer Helicoverpa armigera. To fight the attacking pest, C. platycarpus strategically activated non-enzymatic reactive oxygen species (ROS) scavengers and unleashed methionine sulfoxide reductases to safeguard the integrity of methionine residues. We unveiled for the first time physical interaction between CpMSRB1 and chorismate mutase (CpCM1.1), a pivotal player in the phenylpropanoid pathway. This association fueled the synthesis of phenylpropanoids and enhanced ROS scavenging crucial for repelling herbivores. Repairing CpCM1.1 also boosted salicylic acid production, coordinating defense signaling with jasmonic acid. Additionally, heterologous expression of CpMSRB1 in tomato improved defense against herbivory by enhanced ROS scavenging and polyphenol production. This study demonstrates the role of CpMSRB1 in protecting a major enzyme in the shikimate pathway, reinforcing defense against H. armigera.
The rice heat shock transcription factor OsHSFC1b increases seed weight, size, and vigor, but its function is disrupted by isoaspartyl modification
(John Wiley & Sons, 2025) Achary, Rakesh Kumar; Kamble, Nitin Uttam; Gautam, Shikha; Hazra, Abhijit; Varshney, Vishal; Mahawar, Shivangi; Laha, Saroj; Majee, Manoj
Plant optimizes seed size, weight, vigor, and various other features during seed development, which are important not only for their successful propagation and establishment but also for effective agriculture. Despite several studies conducted, understanding how plants coordinate the regulatory mechanisms to achieve optimal seed size, weight, and vigor remains elusive. Here, our study reveals the role of rice heat shock transcription factor OsHSFC1b in modulating various seed attributes. We observe that OsHSFC1b expression increases during the later stage of seed development and is primarily localized in the embryo. We found that hsfc1b genome-edited lines exhibit compromised seed size, weight, and vigor, while overexpression lines exhibit increased seed size, weight, and vigor compared with the wild-type seeds. Our study further reveals that OsHSFC1b improves seed vigor by activating HSPs and RFO biosynthetic genes involved in protection mechanisms, while also mediating seed size and weight by modulating auxin biosynthesis, endosperm development, and seed filling. We found that upon ageing and stressful environments, OsHSFC1b undergoes isoaspartyl modification that negatively impacts its biological function in seeds. Our MS/MS analyses confirm that asparagine residues near the DNA-binding domain and nuclear localization sequence of OsHSFC1b undergo isoaspartyl modification that adversely affects OsHSFC1b's transactivation activity. However, PROTEIN L-ISOASPARTYL METHYLTRANSFERASE interacts and repairs this isoaspartate-mediated damage, and restores the function of OsHSFC1b. Taken together, our study uncovers how isoaspartyl modification affects the transactivation ability of OsHSFC1b, yet the intervention of PIMT not only repairs this damage but also elevates agronomically important seed traits.
Rice PROTEIN L-ISOASPARTYL METHYLTRANSFERASES provides tolerance against sheath blight disease and repairs ALDH and PBZ1
(Nature Publishing Group, 2026) Gautam, Shikha; Kamble, Nitin Uttam; Achary, Rakesh Kumar; Chandan, Ravindra Kumar; Varshney, Vishal; Hazra, Abhijit; Laha, Saroj; Mahawar, Shivangi; Mehandiratta, Sohela; Singh, Sarvanand; Jha, Gopaljee; Majee, Manoj
Protein L-isoaspartyl methyltransferase (PIMT) regulates key seed traits and abiotic stress tolerance in plants by repairing isoaspartyl (isoAsp) damaged proteins. However, whether PIMT-mediated repair is induced and is required during biotic stress tolerance remains unknown. Using rice lines with OsPIMT overexpression, RNAi-mediated suppression, and genome editing, we show that PIMT enhances tolerance to sheath blight (ShB) caused by Rhizoctonia solani. OsPIMT restricts fungal penetration and colonization of rice sheaths. Co-immunoprecipitation coupled with LC-MS/MS identify various proteins including antioxidant proteins, aldehyde dehydrogenases (ALDH) and pathogenesis-related protein 10 (PBZ1), that undergo isoAsp modification during R. solani infection and interact with PIMT. We show that OsALDH and OsPBZ1 exhibit intrinsic antifungal activity against R. solani, but isoAsp modification impairs their activity, making PIMT mediated repair important. Further, OsALDH enhances tolerance to R. solani by inhibiting lipid peroxidation and ROS homeostasis in rice and fungus. Overall, our study reveals that PIMT enhances ShB tolerance through the repair of isoAsp-damaged proteins important for disease tolerance.