Arabidopsis R-SNARE proteins VAMP721 and VAMP722 are required for cell plate formation.
BACKGROUND
Cell plate formation during plant cytokinesis is facilitated by SNARE complex-mediated vesicle fusion at the cell-division plane. However, our knowledge regarding R-SNARE components of membrane fusion machinery for cell plate formation remains quite limited.


RESULTS
We report the in vivo function of Arabidopsis VAMP721 and VAMP722, two closely sequence-related R-SNAREs, in cell plate formation. Double homozygous vamp721vamp722 mutant seedlings showed lethal dwarf phenotypes and were characterized by rudimentary roots, cotyledons and hypocotyls. Furthermore, cell wall stubs and incomplete cytokinesis were frequently observed in vamp721vamp722 seedlings. Confocal images revealed that green fluorescent protein-tagged VAMP721 and VAMP722 were preferentially localized to the expanding cell plates in dividing cells. Drug treatments and co-localization analyses demonstrated that punctuate organelles labeled with VAMP721 and VAMP722 represented early endosomes overlapped with VHA-a1-labeled TGN, which were distinct from Golgi stacks and prevacuolar compartments. In addition, protein traffic to the plasma membrane, but not to the vacuole, was severely disrupted in vamp721vamp722 seedlings by subcellular localization of marker proteins.


CONCLUSIONS
These observations suggest that VAMP721 and VAMP722 are involved in secretory trafficking to the plasma membrane via TGN/early endosomal compartment, which contributes substantially to cell plate formation during plant cytokinesis.
Key Laboratory of Plant Molecular Physiology, Institute of Botany, Chinese Academy of Sciences, Beijing, China.
Liang
L
Zhang
Haiyan
H
Zhang
Peng
P
Liu
Huaiqing
H
Hao
Jing Bo
JB
Jin
Jinxing
J
Lin
D017360:Arabidopsis / Q000166:cytology* / Q000378:metabolism*; D029681:Arabidopsis Proteins / Q000378:metabolism*; D015415:Biomarkers / Q000378:metabolism; D002462:Cell Membrane / Q000378:metabolism; D002473:Cell Wall / Q000378:metabolism; D048749:Cytokinesis; D004705:Endocytosis; D011992:Endosomes; D005816:Genetic Complementation Test; D049452:Green Fluorescent Proteins / Q000378:metabolism; D008954:Models, Biological; D009154:Mutation / Q000235:genetics; D021381:Protein Transport; D050683:R-SNARE Proteins / Q000378:metabolism*; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D036226:Seedlings / Q000166:cytology / Q000378:metabolism; D021601:trans-Golgi Network / Q000378:metabolism
D029681:Arabidopsis Proteins; D015415:Biomarkers; D050683:R-SNARE Proteins; D011993:Recombinant Fusion Proteins; C570049:VAMP721 protein, Arabidopsis; C570050:VAMP722 protein, Arabidopsis; D049452:Green Fluorescent Proteins