Requirement of R-SNAREs VAMP721 and VAMP722 for the gametophyte activity, embryogenesis and seedling root development in Arabidopsis

Abstract

Membrane fusion between transport vesicles and target membranes is mediated by SNARE complex, a key regulator of vesicular traffic. A functional SNARE complex consists of four coiled-coil helical bundles supplied by Q-SNARE and R-SNARE. Here, we analyze the Arabidopsis R-SNAREs VAMP721 and VAMP722. Reciprocal crosses indicated that the transmission of vamp721vamp722 allele was slightly reduced through gametophytes of VAMP721−/−VAMP722+/− plants and obviously blocked through pollen of VAMP721+/−VAMP722−/− plants. The observation of embryogenesis showed that vamp721vamp722 mutations resulted in abnormal embryo morphology, such as embryos with asymmetric developing cotyledons, three developing cotyledons, unfolded cotyledons and roots, and partial arrested embryo development at globular stage. Moreover, double mutant seedlings grew rudimentary roots displaying reduced meristem zone, disorganized QC cells, and disordered cell layer pattern and cell file alignment. Confocal images revealed that VAMP721 and VAMP722 were expressed throughout whole root. Taken together, our results suggest that VAMP721 and VAMP722 are involved in gametophyte transmission, embryo development and seedling root growth in Arabidopsis.