Abstract

Pollen-stigma interactions constitute the initial step of male-female communication during flowering plant reproduction, ensuring compatible pollen germination and fertilization. In Arabidopsis, the receptor kinase FERONIA (FER) regulates this process, but its downstream signaling mechanisms remain incompletely understood. Here, we identify Glutathione S-Transferase Phi 10 (GSTF10) as a FER-interacting protein. Physical interaction between FER and GSTF10 was confirmed by yeast two-hybrid, luciferase complementation, and co-immunoprecipitation assays. In vitro phosphorylation assays showed that FER directly phosphorylates GSTF10. Loss of GSTF10 function led to accelerated pollen hydration on the stigma and reduced reactive oxygen species (ROS) levels in stigma papillae, accompanied by enhanced pollen tube elongation. Genetic epistasis analysis revealed that the fer-4 gstf10-1 double mutant phenocopied the gstf10-1 single mutant in terms of pollen tube length, placing GSTF10 downstream of FER in regulating pollen tube growth. In addition, gstf10 mutants produce more seeds per silique. Collectively, these findings suggest that FER-mediated phosphorylation of GSTF10 contributes to restraining pollen hydration and tube elongation, likely through modulating ROS homeostasis in the stigma. This study uncovers a previously unrecognized signaling module that governs early events of compatible pollination.