AhNPR4B Interacts with AhPR2-Like and May Contribute to Disease Resistance and Cold Tolerance in Peanut

Peanut (Arachis hypogaea L.) production faces persistent threats from various infectious diseases. Planting healthy varieties with robust botanical defense networks is critical for minimizing future costs. Non-expressor of pathogenesis-related (NPR) regulators are involved in immune activation and act as key targets for deeper stress adaptation, and are thus promising targets for genetic enhancement. In this study, we characterized the peanut NPR4B protein and demonstrated its local subcellular binding to the nucleus. Ectopic overexpression of AhNPR4B in Arabidopsis thaliana significantly enhanced resistance to the necrotrophic pathogen Botrytis cinerea and enhanced cold tolerance, as supported by quantitative and statistical analyses (p < 0.05). As regards underlying molecular events, Y2H (Yeast 2-Hybrid) analysis revealed a binding in vitro physical relation of AhPR2-like to AhNPR4B. This binding was demonstrated in vivo through BiFC (Bimolecular Fluorescence Complementation). These results suggest that the AhNPR4B-AhPR2-like complex may act as a key regulatory module associated with biotic and abiotic stress signaling, potentially contributing to broad-spectrum stress resistance. These findings provide foundational insights into the functional roles of AhNPR4B and its interaction with AhPR2-like in regulating stress resistance and support its potential as a candidate target for future genetic improvements to enhance stress resilience in peanuts.