Involvement of the vacuoles of the endodermis in the early process of shoot gravitropism in Arabidopsis.
The endodermal cells of the shoot are thought to be the gravity-sensing cells in Arabidopsis. The amyloplasts in the endodermis that sediment in the direction of gravity may act as statoliths. Endodermis-specific expression of SGR2 and ZIG using the SCR promoter could complement the abnormal shoot gravitropism of the sgr2 and zig mutants, respectively. The abnormalities in amyloplast sedimentation observed in both mutants recovered simultaneously. These results indicate that both genes in the endodermal cell layer are crucial for shoot gravitropism. ZIG encodes AtVTI11, which is a SNARE involved in vesicle transport to the vacuole. The fusion protein of SGR2 and green fluorescent protein localized to the vacuole and small organelles. These observations indicate that ZIG and SGR2 are involved in the formation and function of the vacuole, a notion supported by the results of subcellular analysis of the sgr2 and zig mutants with electron microscopy. These results strongly suggest that the vacuole participates in the early events of gravitropism and that SGR2 and ZIG functions are involved.
Morita
Miyo Terao
MT
Graduate School of Biological Sciences, Nara Institute of Science and Technology, Nara 630-0101, Japan.
Kato
Takehide
T
Nagafusa
Kiyoshi
K
Saito
Chieko
C
Ueda
Takashi
T
Nakano
Akihiko
A
Tasaka
Masao
M
D017360:Arabidopsis / Q000166:cytology / Q000235:genetics* / Q000502:physiology; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism; D002478:Cells, Cultured; D018506:Gene Expression Regulation, Plant / Q000502:physiology; D005816:Genetic Complementation Test; D018522:Gravitropism / Q000502:physiology*; D049452:Green Fluorescent Proteins; D008164:Luminescent Proteins / Q000235:genetics / Q000378:metabolism; D008565:Membrane Proteins / Q000235:genetics / Q000378:metabolism; D018613:Microscopy, Confocal; D008854:Microscopy, Electron; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism; D018520:Plant Shoots / Q000235:genetics* / Q000502:physiology; D018087:Plastids / Q000502:physiology / Q000648:ultrastructure; D050766:Qb-SNARE Proteins; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism; D015398:Signal Transduction / Q000235:genetics; D014617:Vacuoles / Q000235:genetics* / Q000378:metabolism / Q000648:ultrastructure
D029681:Arabidopsis Proteins; D008164:Luminescent Proteins; D008565:Membrane Proteins; D010940:Plant Proteins; D050766:Qb-SNARE Proteins; D011993:Recombinant Fusion Proteins; C401308:SCR protein, Brassica oleracea; C120751:vesicle transport v-SNARE 11 protein, Arabidopsis; C120752:vesicle transport v-SNARE 12 protein, Arabidopsis; D049452:Green Fluorescent Proteins