A SNARE Complex Containing SGR3/AtVAM3 and ZIG/VTI11 in Gravity-Sensing Cells Is Important for Arabidopsis Shoot Gravitropism

Plants can sense the direction of gravity and change the growth orientation of their organs. The molecular mechanisms of gravity sensing and signal transduction during gravitropism are not well known. We have isolated several shoot gravitropism (sgr) mutants of Arabidopsis. The sgr3-1 mutant exhibit...

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Bibliographic Details
Published in:Proceedings of the National Academy of Sciences - PNAS 2003-07, Vol.100 (14), p.8589-8594
Main Authors: Yano, Daisuke, Sato, Masakazu, Saito, Chieko, Sato, Masa H., Morita, Miyo Terao, Tasaka, Masao
Format: Article
Language:English
Subjects:
Amino Acid Sequence
Amyloplasts
Antibodies
Antiserum
Arabidopsis - genetics
Arabidopsis - physiology
Arabidopsis Proteins - genetics
Arabidopsis Proteins - physiology
Biological Sciences
Biological Transport
Cells
Endodermis
Ethylmaleimide - pharmacology
Flowers & plants
Gravitropism
Gravitropism - genetics
Gravitropism - physiology
Gravity Sensing - physiology
Immunoprecipitation
Inflorescences
Macromolecular Substances
Membrane Proteins - genetics
Membrane Proteins - physiology
Microscopy, Electron
Molecular Sequence Data
Phenotype
Plant cells
Plant growth
Plant Shoots - physiology
Protein Interaction Mapping
Qa-SNARE Proteins
Qb-SNARE Proteins
Receptors, Cytoplasmic and Nuclear - genetics
Receptors, Cytoplasmic and Nuclear - physiology
Sequence Alignment
Sequence Homology, Amino Acid
SNARE Proteins
Vacuoles
Vesicular Transport Proteins
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Summary:Plants can sense the direction of gravity and change the growth orientation of their organs. The molecular mechanisms of gravity sensing and signal transduction during gravitropism are not well known. We have isolated several shoot gravitropism (sgr) mutants of Arabidopsis. The sgr3-1 mutant exhibits a reduced gravitropic response in the inflorescence stems. In the inflorescence stems of Arabidopsis, gravity is sensed in endodermal cells that contain sedimentable amyloplasts. In sgr3-1, some amyloplasts in the endodermis failed to sediment in the direction of gravity. SGR3 encodes a syntaxin, AtVAM3, which had previously been cloned as a homologue of yeast Vam3p. AtVAM3 is localized to the prevacuolar compartment and vacuole and is suggested to function in vesicle transport to the vacuole. We have also cloned another soluble N-ethylmaleimide-sensitive factor attachment protein receptor (SNARE), ZIG/AtVTI11, a mutation that causes abnormal gravitropism. This mutant displayed an abnormal distribution of amyloplasts in the endodermal cells similar to that in sgr3-1. Endodermis-specific expression of SGR3 and ZIG by using the SCR promoter could complement the abnormal shoot gravitropism of each mutant. Protein-protein interaction between AtVAM3 and AtVTI11 in the endodermal cells was detected immunologically. The sgr3-1 mutation appeared to reduce the affinity of AtVAM3 for AtVTI11 or SYP5. These results suggest that vesicle transport to the prevacuolar compartment/vacuole in the endodermal cells, mediated by a specific SNARE complex containing AtVAM3 and AtVTI11, plays an important role in shoot gravitropism.
ISSN:0027-8424
1091-6490
DOI:10.1073/pnas.1430749100