Cotton leaf curl Multan virus subverts the processing of hydroxyproline-rich systemin to suppress tobacco defenses against insect vectors.

This article focuses on the tripartite interactions among Cotton leaf curl Multan virus (CLCuMuV), its whitefly vector Bemisia tabaci, and host plants, particularly tobacco. It reports that infection by CLCuMuV and its associated betasatellite (CLCuMuB) enhances whitefly survival, fecundity, and attraction to infected plants by suppressing the plant jasmonic acid (JA) defense signaling pathway. The study identifies the βC1 protein encoded by CLCuMuB as a key factor that interacts with the tobacco subtilisin-like protease NtSBT1.7, interfering with its processing of the precursor protein NtpreproHypSysB, which normally activates JA-related defenses against whiteflies. These findings elucidate a molecular mechanism by which CLCuMuV manipulates plant defenses to benefit its insect vector, contributing to the understanding of virus–plant–insect ecological and evolutionary dynamics.