title: SGR2, a phospholipase-like protein, and ZIG/SGR4, a SNARE, are involved in the shoot gravitropism of Arabidopsis.
abstract: In higher plants, the shoot and the root generally show negative and positive gravitropism, respectively. To elucidate the molecular mechanisms involved in gravitropism, we have isolated many shoot gravitropism mutants in Arabidopsis. The sgr2 and zig/sgr4 mutants exhibited abnormal gravitropism in both inflorescence stems and hypocotyls. These genes probably are involved in the early step(s) of the gravitropic response. The sgr2 mutants also had misshapen seed and seedlings, whereas the stem of the zig/sgr4 mutants elongated in a zigzag fashion. The SGR2 gene encodes a novel protein that may be part of a gene family represented by bovine phosphatidic acid-preferring phospholipase A1 containing a putative transmembrane domain. This gene family has been reported only in eukaryotes. The ZIG gene was found to encode AtVTI11, a protein that is homologous with yeast VTI1 and is involved in vesicle transport. Our observations suggest that the two genes may be involved in a vacuolar membrane system that affects shoot gravitropism.
authors.affiliation: Department of Botany, Graduate School of Science, Kyoto University, Sakyo-ku, Kyoto 606-8502, Japan.
authors.forename: Takehide
authors.initials: T
authors.lastname: Kato
authors.forename: Miyo Terao
authors.initials: MT
authors.lastname: Morita
authors.forename: Hidehiro
authors.initials: H
authors.lastname: Fukaki
authors.forename: Yoshiro
authors.initials: Y
authors.lastname: Yamauchi
authors.forename: Michiko
authors.initials: M
authors.lastname: Uehara
authors.forename: Mitsuru
authors.initials: M
authors.lastname: Niihama
authors.forename: Masao
authors.initials: M
authors.lastname: Tasaka
mesh_terms: D000595:Amino Acid Sequence; D017360:Arabidopsis / Q000235:genetics* / Q000254:growth & development / Q000528:radiation effects; D029681:Arabidopsis Proteins / Q000235:genetics* / Q000378:metabolism; D002874:Chromosome Mapping; D003001:Cloning, Molecular; D018506:Gene Expression Regulation, Plant / Q000528:radiation effects; D005816:Genetic Complementation Test; D018522:Gravitropism / Q000235:genetics* / Q000502:physiology / Q000528:radiation effects; D008027:Light; D008565:Membrane Proteins / Q000235:genetics / Q000378:metabolism; D008969:Molecular Sequence Data; D009154:Mutation; D010641:Phenotype; D010740:Phospholipases / Q000235:genetics* / Q000378:metabolism; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism; D018520:Plant Shoots / Q000235:genetics* / Q000254:growth & development / Q000528:radiation effects; D030821:Plants, Genetically Modified; D050766:Qb-SNARE Proteins; D017386:Sequence Homology, Amino Acid; D015398:Signal Transduction; D014617:Vacuoles / Q000378:metabolism
chemical_list: D029681:Arabidopsis Proteins; D008565:Membrane Proteins; D010940:Plant Proteins; D050766:Qb-SNARE Proteins; C120751:vesicle transport v-SNARE 11 protein, Arabidopsis; C120752:vesicle transport v-SNARE 12 protein, Arabidopsis; D010740:Phospholipases; C455511:SGR2 phospholipase, Arabidopsis