PRL1 negatively regulates Rho GTPase-independent and - dependent signaling pathways maintaining actin microfilament dynamic for pavement cell morphogenesis

Abstract

AbstractActin dynamic is critical for cell morphogenesis in plants, but the signaling mechanisms underlying its regulation are not well understood. Here we foundPRL1(PleiotropicRegulatoryLocus1) modulates leaf pavement cell (PC) morphogenesis in Arabidopsis by maintaining the dynamic homeostasis of actin microfilaments (MF). Our previous studies indicated PC shape formation was mediated by the counteracting ROP2 and ROP6 signaling pathways that promote the organization of cortical MF and microtubules (MT), respectively. Our genetic screen forROP6enhancers identifiedprl1alleles. Genetic analysis suggested thatprl1acted synergistically withROP2andROP6in regulation of PC morphogenesis. We further found that the activities of ROP2 and ROP6 were increased and decreased inprl1mutants, respectively. Interestinglyprl1was found to prefer to depolymerize MF independent of ROP2 and ROP6. Stress (high salinity and low temperature) induced similar changes of ROP activities as doprl1mutations. Together our findings provided evidence that PRL1 governed two signaling pathways that counteractively maintain actin dynamics and resultant cell morphogenesis.