Abstract
Although polar auxin transport was known to play a pivotal role in vascular pattern formation, its molecular mechanism is not sufficiently elucidated. To understand the molecular mechanism of vascular pattern formation, we have analyzed van3 mutants characterized by fragmented veins. We have shown that VAN3 encodes an ARF-GAP protein that function on the TGN. As a first step toward characterizing molecular function of VAN3, we performed phenotypic analysis of various alleles of van3 mutants. This analysis suggested an indispensable role of PH domain in establishing vascular continuity. We have previously shown that PH domain in VAN3 strongly binds to PI4-P. Interestingly, mutation in the CVP2 that encodes an enzyme producing PI4-P phenocopies the van3. These results indicate that PI4-P plays essential function to establish the vascular continuity. We also isolated new protein that functions in the PI4-P-mediated process. Taken together, we will discuss the role of phosphoinositide-signaling in vascular development.
