A Fusarium graminearum effector protein subverts plant immunity by targeting the TaRPM1–TaHSA32 regulatory axis

Fusarium graminearum is a devastating wheat pathogen that suppresses host immunity to promote infection. Here, we show that the secreted effector FgUP7 contributes to pathogen virulence by targeting the NLR immune receptor TaRPM1. TaRPM1 positively regulates wheat resistance to F. graminearum. By binding the coiled-coil domain, FgUP7 interferes with early NLR oligomerization and promotes TaRPM1 destabilization. In contrast, the heat-induced co-chaperone TaHSA32 associates with TaRPM1 to stabilize the receptor and prime NLR complexes for activation under fluctuating temperatures. Competitive displacement of TaHSA32 by FgUP7 removes this protective layer, rendering TaRPM1 vulnerable to degradation and thereby diminishing host immune surveillance. This antagonistic interplay provides a mechanistic framework explaining how elevated temperature and pathogen effectors synergistically compromise plant immunity. Notably, transgenic manipulation of TaHSA32 or TaRPM1 does not affect major agronomic traits, highlighting the potential for targeted improvement of resistance. Furthermore, the RPM1–HSA32 regulatory axis is functionally conserved in the model grass Brachypodium distachyon, suggesting evolutionary conservation across monocots.