Abstract
Arabidopsis zig mutant exhibits abnormal shoot gravitropism and morphological defects in stem and leaves. The ZIG gene encodes a Qb-SNARE VTI11 that plays roles in vesicular trafficking between trans-Golgi network and vacuoles.
To understand the molecular basis of vesicle transport involved in physiological function of higher plants, we performed a screening for the second mutation that can suppress defects of zig-1. zig suppressor 3(zip3) partially suppresses abnormalities in gravitropism and morphology observed in zig-1. The cytological analysis revealed that the zip3-1 partially restored the dynamics of amyroplasts and vacuolar membrane in the gravity-sensing endodermal cells.
Based on the map position, a nonsense mutation was found in AtVPS35b gene in the zip3 mutant. The complementation analysis identified ZIP3 as AtVPS35b encoding one of three Arabidopsis genes homologous to yeast VPS35. The Vps35p is a subunit of retromer involved in retrograde transport from prevacuolar compartment to TGN in yeast.
