FERONIA receptor-like kinase regulates RHO GTPase signaling of root hair development

摘要

Plant RHO GTPases (RAC/ROPs) mediate multiple extracellular signals ranging from hormone to stress and regulate diverse cellular processes important for polarized cell growth, differentiation, rndevelopment, reproduction, and responses to the environment rnThey shuttle between the GDP-bound inactive state and the GTP-bound activated state and their activation is predominantly mediated by a family of guanine nucleotide exchange factors (GEFs) referred to as ROPGEFs. Using the Arabidopsis ROPGEF1 as bait we identified members of a receptor-like kinase (RLK) family as potential upstream regulators for RAC/ROP signaling. NADPH oxidase-derived reactive oxygen species (ROS) are emerging as important rnregulators for growth and development and play a crucial role in mediating RAC/ROP-regulated root hair development a polarized rncell growth process. We therefore screened T-DNA insertion mutants in these RLKs for root hair defects and found that mutations rnin one of them, At3g51550 encoding the FERONIA (FER) receptor-like rnkinase, induced severe root hair defects. We show that the far phenotypes correlated with reduced levels of active RAC/ ROPs and NADPH oxidase-dependent auxin-regulated ROS accumulation rnin roots and root hairs and that up-regulating RAC/ROP signaling in fer countered the mutant phenotypes. Taken together, these observations strongly support FER as an upstream regulator for the RAC/ROP-signaled pathway that controls ROS-mediated root hair development Moreover, FER was pulled down by ROP2 GTPase in a guanine nucleotide-regulated manner implying a dynamic rnsignaling complex involving FER, a ROPGEF, and a RAC/ROP.