title: Vacuolar/pre-vacuolar compartment Qa-SNAREs VAM3/SYP22 and PEP12/SYP21 have interchangeable functions in Arabidopsis.
abstract: 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.
authors.affiliation: Department of Biological Sciences, Graduate School of Science, The University of Tokyo, Bunkyo-ku, Tokyo 113-0033, Japan. tuemura@biol.s.u-tokyo.ac.jp
authors.forename: Tomohiro
authors.initials: T
authors.lastname: Uemura
authors.forename: Miyo Terao
authors.initials: MT
authors.lastname: Morita
authors.forename: Kazuo
authors.initials: K
authors.lastname: Ebine
authors.forename: Yusuke
authors.initials: Y
authors.lastname: Okatani
authors.forename: Daisuke
authors.initials: D
authors.lastname: Yano
authors.forename: Chieko
authors.initials: C
authors.lastname: Saito
authors.forename: Takashi
authors.initials: T
authors.lastname: Ueda
authors.forename: Akihiko
authors.initials: A
authors.lastname: Nakano
mesh_terms: D017360:Arabidopsis / Q000235:genetics* / Q000378:metabolism; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D004269:DNA, Bacterial / Q000235:genetics; D018506:Gene Expression Regulation, Plant; D016254:Mutagenesis, Insertional; D009154:Mutation; D010641:Phenotype; D054817:Pollination; D011401:Promoter Regions, Genetic; D050765:Qa-SNARE Proteins / Q000235:genetics / Q000378:metabolism*; D014617:Vacuoles / Q000378:metabolism*
chemical_list: C489890:ATPEP12 protein, Arabidopsis; D029681:Arabidopsis Proteins; D004269:DNA, Bacterial; D050765:Qa-SNARE Proteins; C036483:T-DNA; C108430:Vam3 protein, Arabidopsis