Vacuolar/pre‐vacuolar compartment Qa‐SNAREs VAM3/SYP22 and PEP12/SYP21 have interchangeable functions in Arabidopsis

• Published in: The Plant journal : for cell and molecular biology 2010-12, Vol.64 (5), p.864-873
• Main Authors: Uemura, Tomohiro, Morita, Miyo Terao, Ebine, Kazuo, Okatani, Yusuke, Yano, Daisuke, Saito, Chieko, Ueda, Takashi, Nakano, Akihiko
• Format: Article
• Language: English
• Subjects: Arabidopsis; Arabidopsis - genetics; Arabidopsis - metabolism; Arabidopsis Proteins - genetics; Arabidopsis Proteins - metabolism; Biological and medical sciences; Cell physiology; DNA, Bacterial - genetics; Flowers & plants; Fundamental and applied biological sciences. Psychology; Gene Expression Regulation, Plant; Membranes; Molecular and cellular biology; Mutagenesis, Insertional; Mutation; Phenotype; Plant physiology and development; Pollination; pre‐vacuolar compartment; Promoter Regions, Genetic; Proteins; Qa-SNARE Proteins - genetics; Qa-SNARE Proteins - metabolism; Secretion. Exocytosis; SNARE; vacuolar transport; vacuole; Vacuoles - metabolism
• ISSN: 0960-7412; 1365-313X
• DOI: 10.1111/j.1365-313X.2010.04372.x

SNAREs (soluble N‐ethylmaleimide sensitive factor attachment protein receptors) mediate specific membrane fusion between transport vesicles or organelles and target membranes. VAM3/SYP22 and PEP12/SYP21 are Qa‐SNAREs that act in the vacuolar transport pathway of Arabidopsis thaliana, and are localized predominantly on the vacuolar membrane and the pre‐vacuolar compartment (PVC), respectively. Previous studies have shown that loss‐of‐function mutants of VAM3/SYP22 or PEP12/SYP21 showed male gametophytic lethality, suggesting that VAM3/SYP22 and PEP12/SYP21 possess different, non‐redundant functions. We have re‐evaluated the effects of mutations in these genes using T‐DNA insertion mutants in the Columbia accession. We found that a mutation in VAM3/SYP22 (vam3‐1) caused pleiotropic abnormalities, including semi‐dwarfism and wavy leaves. In contrast, a loss‐of‐function mutant of PEP12/SYP21 (pep12) showed no apparent abnormal phenotype. We also found that the double vam3‐1 pep12 mutant had severely reduced fertilization competence, although male and female gametophytes (vam3‐1⁻pep12⁻) maintained the ability to fertilize. Moreover, promoter swapping analysis revealed that expression of a GFP-PEP12/SYP21 fusion under the control of the VAM3/SYP22 promoter suppressed all phenotypes of the vam3‐1 mutant. These results indicate that the functions of VAM3/SYP22 and PEP12/SYP21 were redundant and interchangeable.