The expression of LjROP4 is required for rhizobial infection in Lotus japonicus
Canadian Journal of Plant Science
Increasing evidence suggests that ROP (Rho of plant) GTPases play important roles in the rhizobium-legume symbiotic nodulation, but the molecular mechanisms on their regulation in symbiosis remain poorly understood. In this study, we showed that LjROP4 (Rho of plant 4 in Lotus japonicus) is involved in the symbiotic interaction between Lotus japonicus and Mesorhizobium loti. Tissue expression analysis showed that LjROP4 expressed highly in root. Histochemical staining analysis showed that after
... s showed that after rhizobia inoculation, GUS reporter activity increased obviously in root vascular bundle, root tip and lateral root primordia. During nodule development, GUS activity was detected in the cortex of nodule primordia and young nodules. In the mature nodules, GUS activity was detected only in the vascular bundle of mature nodules. Compared with the control, overexpression of ROP4 and ROP4-CA produced much more pronounced root hair swelling and curling induced by M. loti. The infection event and nodule number increased obviously, which was in consistent with this promotion of root hair deformation Moreover, RNA interference (RNAi) of LjROP4 produced opposite phenotypes. These data suggest that LjROP4 is required for root hair deformation during rhizobial infection. Thus, our study provides important information about root hair deformation responses induced by nod factors in the early stage of symbiotic interaction.