Cellular Responses in the Pigeonpea Wild Relative Cajanus platycarpus to Helicoverpa armigera Herbivory: The Role of Methionine Sulfoxide Reductase B1 (CpMSRB1) in Enhanced Defense.

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. [Formula: see text] Copyright © 2025 The Author(s). This is an open access article distributed under the CC BY-NC-ND 4.0 International license.