The small GTPase MaROP10 interacts with MaRIC6 to regulate rhizobial infection in Melilotus albus

The symbiotic nitrogen fixation process between legume roots and rhizobia initiates at the root hairs. Rhizobia initially colonize the tip of the root hairs and induce its curling to become entrapped. However, the specific molecular mechanisms underlying root hair deformation and curling in response to rhizobial infection remain unclear. In this study, transcriptome analysis of wild-type JiMa389 and nodulation-deficient mutant jima61 of Melilotus albus, the Rho-like small GTPase MaROP10. Our results show that MaROP10 functions as an interacts with the Nod factor receptor NFR5 to regulate rhizobia-induced root hair deformation and infection thread formation during the early stages of rhizobial infection. To elucidate the mechanism of MaROP10, we further identified its downstream potential effector protein, MaRIC6, which positively regulates root hair deformation and infection thread formation. Taken together, MaROP10 likely integrates signals from the symbiotic receptor NFR5 to regulate downstream signaling pathways through its effector MaRIC6, thereby coordinating root hair deformation and infection thread development during the early stages of rhizobial infection.