title: The occurrence of 'bulbs', a complex configuration of the vacuolar membrane, is affected by mutations of vacuolar SNARE and phospholipase in Arabidopsis.
abstract: The plant vacuole fulfills a variety of functions, and is essential for plant growth and development. We previously identified complex and mobile structures on the continuous vacuolar membrane, which we refer to as 'bulbs'. To ascertain their biological significance and function, we searched for markers associated with bulbs, and mutants that show abnormalities with respect to bulbs. We observed bulb-like structures after expression of non-membranous proteins as well as the functional soluble N-ethylmaleimide-sensitive factor attachment protein receptor (SNARE) molecules VAM3 and VTI11. Bulbs are formed in more tissues than previously reported, including flowering organs, suspension culture cells, endodermal cells in the flowering stem, and at very early stages of seed germination. Using existing and newly developed marker lines, we found that the frequency of bulb occurrence is significantly decreased in multiple shoot gravitropism (sgr) mutants, which are known to have a defect in vacuolar membrane properties in endodermal cells. Based on results with new marker lines, which enabled us to observe the process of bulb biogenesis, and analysis of the phenotypes of these mutants, we propose multiple mechanisms for bulb formation, one of which may be that used for formation of transvacuolar strands.
authors.affiliation: Molecular Membrane Biology Laboratory, RIKEN Advanced Science Institute, Wako, Saitama 351-0198, Japan. chiezo@riken.jp
authors.forename: Chieko
authors.initials: C
authors.lastname: Saito
authors.forename: Tomohiro
authors.initials: T
authors.lastname: Uemura
authors.forename: Chie
authors.initials: C
authors.lastname: Awai
authors.forename: Motoki
authors.initials: M
authors.lastname: Tominaga
authors.forename: Kazuo
authors.initials: K
authors.lastname: Ebine
authors.forename: Jun
authors.initials: J
authors.lastname: Ito
authors.forename: Takashi
authors.initials: T
authors.lastname: Ueda
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Abe
authors.forename: Miyo Terao
authors.initials: MT
authors.lastname: Morita
authors.forename: Masao
authors.initials: M
authors.lastname: Tasaka
authors.forename: Akihiko
authors.initials: A
authors.lastname: Nakano
mesh_terms: D017360:Arabidopsis / Q000201:enzymology / Q000235:genetics / Q000502:physiology* / Q000648:ultrastructure*; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D001692:Biological Transport; D015415:Biomarkers / Q000378:metabolism; D002462:Cell Membrane / Q000378:metabolism / Q000648:ultrastructure*; D035263:Flowering Tops / Q000648:ultrastructure; D018525:Germination; D018522:Gravitropism / Q000502:physiology*; D049452:Green Fluorescent Proteins; D009154:Mutation; D010641:Phenotype; D010740:Phospholipases / Q000235:genetics / Q000378:metabolism; D019441:Plant Epidermis / Q000648:ultrastructure; D018515:Plant Leaves / Q000648:ultrastructure; D018517:Plant Roots / Q000648:ultrastructure; D018520:Plant Shoots / Q000648:ultrastructure; D050765:Qa-SNARE Proteins / Q000235:genetics / Q000378:metabolism; D050766:Qb-SNARE Proteins / Q000235:genetics / Q000378:metabolism; D012639:Seeds / Q000502:physiology; D014617:Vacuoles / Q000201:enzymology / Q000378:metabolism / Q000648:ultrastructure*
chemical_list: D029681:Arabidopsis Proteins; D015415:Biomarkers; D050765:Qa-SNARE Proteins; D050766:Qb-SNARE Proteins; C108430:Vam3 protein, Arabidopsis; C120751:vesicle transport v-SNARE 11 protein, Arabidopsis; D049452:Green Fluorescent Proteins; D010740:Phospholipases; C455511:SGR2 phospholipase, Arabidopsis