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PMID:11846875

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Citation

Taji, T, Ohsumi, C, Iuchi, S, Seki, M, Kasuga, M, Kobayashi, M, Yamaguchi-Shinozaki, K and Shinozaki, K (2002) Important roles of drought- and cold-inducible genes for galactinol synthase in stress tolerance in Arabidopsis thaliana. Plant J. 29:417-26

Abstract

Raffinose family oligosaccharides (RFO) accumulating during seed development are thought to play a role in the desiccation tolerance of seeds. However, the functions of RFO in desiccation tolerance have not been elucidated. Here we examine the functions of RFO in Arabidopsis thaliana plants under drought- and cold-stress conditions, based on the analyses of function and expression of genes involved in RFO biosynthesis. Sugar analysis showed that drought-, high salinity- and cold-treated Arabidopsis plants accumulate a large amount of raffinose and galactinol, but not stachyose. Raffinose and galactinol were not detected in unstressed plants. This suggests that raffinose and galactinol are involved in tolerance to drought, high salinity and cold stresses. Galactinol synthase (GolS) catalyses the first step in the biosynthesis of RFO from UDP-galactose. We identified three stress-responsive GolS genes (AtGolS1, 2 and 3) among seven Arabidopsis GolS genes. AtGolS1 and 2 were induced by drought and high-salinity stresses, but not by cold stress. By contrast, AtGolS3 was induced by cold stress but not by drought or salt stress. All the GST fusion proteins of GST-AtGolS1, 2 and 3 expressed in Escherichia coli had galactinol synthase activities. Overexpression of AtGolS2 in transgenic Arabidopsis caused an increase in endogenous galactinol and raffinose, and showed reduced transpiration from leaves to improve drought tolerance. These results show that stress-inducible galactinol synthase plays a key role in the accumulation of galactinol and raffinose under abiotic stress conditions, and that galactinol and raffinose may function as osmoprotectants in drought-stress tolerance of plants.

Links

PubMed

Keywords

Acclimatization/genetics; Acclimatization/physiology; Amino Acid Sequence; Arabidopsis/enzymology; Arabidopsis/genetics; Arabidopsis/growth & development; Arabidopsis Proteins; Carbohydrate Sequence; Cold Temperature; Disaccharides/chemistry; Disaccharides/metabolism; Disasters; Escherichia coli/genetics; Galactosyltransferases/genetics; Galactosyltransferases/metabolism; Gene Expression; Molecular Sequence Data; Molecular Structure; Phylogeny; Plant Transpiration/genetics; Plant Transpiration/physiology; Plants, Genetically Modified; Raffinose/analogs & derivatives; Raffinose/chemistry; Raffinose/metabolism; Salts; Seeds/enzymology; Seeds/genetics; Seeds/growth & development; Sequence Homology, Amino Acid; Soil/analysis; Transcription Factors/genetics; Transcription Factors/metabolism; Water/metabolism

Significance

Annotations

Gene product Qualifier GO Term Evidence Code with/from Aspect Extension Notes Status

ARATH:GOLS1

involved_in

GO:0009737: response to abscisic acid

ECO:0000270: expression pattern evidence used in manual assertion

P

Seeded From UniProt

complete

ARATH:GOLS1

involved_in

GO:0009651: response to salt stress

ECO:0000270: expression pattern evidence used in manual assertion

P

Seeded From UniProt

complete

ARATH:GOLS1

involved_in

GO:0009414: response to water deprivation

ECO:0000270: expression pattern evidence used in manual assertion

P

Seeded From UniProt

complete

ARATH:GOLS1

enables

GO:0047216: inositol 3-alpha-galactosyltransferase activity

ECO:0000314: direct assay evidence used in manual assertion

F

Seeded From UniProt

complete

ARATH:GOLS3

involved_in

GO:0009409: response to cold

ECO:0000270: expression pattern evidence used in manual assertion

P

Seeded From UniProt

complete

ARATH:GOLS3

enables

GO:0047216: inositol 3-alpha-galactosyltransferase activity

ECO:0000314: direct assay evidence used in manual assertion

F

Seeded From UniProt

complete

ARATH:GOLS2

involved_in

GO:0009737: response to abscisic acid

ECO:0000270: expression pattern evidence used in manual assertion

P

Seeded From UniProt

complete

ARATH:GOLS2

involved_in

GO:0009651: response to salt stress

ECO:0000270: expression pattern evidence used in manual assertion

P

Seeded From UniProt

complete

ARATH:GOLS2

involved_in

GO:0009414: response to water deprivation

ECO:0000270: expression pattern evidence used in manual assertion

P

Seeded From UniProt

complete

ARATH:GOLS2

enables

GO:0047216: inositol 3-alpha-galactosyltransferase activity

ECO:0000314: direct assay evidence used in manual assertion

F

Seeded From UniProt

complete


See also

References

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