ARF GTPase machinery at the plasma membrane regulates auxin transport-mediated plant growth.

Abstract

VAN3 is a plant ACAP-type ADP-ribosylation factor-GTPase activating protein (ARF-GAP) that regulates auxin transport-mediated plant morphogenesis such as continuous venation and lateral root development in Arabidopsis. Previous studies suggested that VAN3 localizes at the plasma membrane (PM) and intracellular structures. However, the role of PM localization in mediating the van3 mutant phenotype is not clear. Here we performed subcellular localization analysis of VAN3 and its regulators CVP2 and VAB to determine their endogenous functions. We found that GFP-tagged CVP2 and VAB preferentially localize at the PM in stably transformed plants. We determined that transgenic plants with lower expression levels of GFP- or mRFP-tagged VAN3 displayed PM localization, which was sufficient to rescue the van3 mutant. Functional VAN3-mRFP and VAB-GFP colocalized at PMs. The van3 mutant phenotype was suppressed by mutation of VAN7/GNOM, which encodes an ARF-GEF that localizes at the PM and Golgi apparatus. These combined results suggest that ARF-GTPase machinery at the PM regulates auxin transport-mediated plant growth and development.