Overexpression of GSH1 gene mimics transcriptional response to low temperature during seed vernalization treatment of Arabidopsis.
Keeping imbibed seeds at low temperatures for a certain period, so-called seed vernalization (SV) treatment, promotes seed germination and subsequent flowering in various plants. Vernalization-promoting flowering requires GSH. However, we show here that increased GSH biosynthesis partially mimics SV treatment in Arabidopsis thaliana. SV treatment (keeping imbibed seeds at 4°C for 24 h) induced a specific pattern of gene expression and promoted subsequent flowering in WT A. thaliana. A similar pattern was observed at 22°C in transgenic (35S-GSH1) plants overexpressing the γ-glutamylcysteine synthetase gene GSH1, coding for an enzyme limiting GSH biosynthesis, under the control of the cauliflower mosaic virus 35S promoter. This pattern of gene expression was further strengthened at 4°C and indistinguishable from the WT pattern at 4°C. However, flowering in 35S-GSH1 plants was less responsive to SV treatment than in WT plants. There was a difference in the transcript behavior of the flowering repressor FLC between WT and 35S-GSH1 plants. Unlike other genes responsive to SV treatment, the SV-dependent decrease in FLC in WT plants was reversed in 35S-GSH1 plants. SV treatment increased the GSSG level in WT seeds while its level was high in 35S-GSH1 plants, even at a non-vernalizing temperature. Taking into consideration that low temperatures stimulate GSH biosynthesis and cause oxidative stress, GSSG is considered to trigger a low-temperature response, although enhanced GSH synthesis was not enough to completely mimic the SV treatment.
Research Institute for Biological Sciences-RIBS Okayama, Okayama Prefectural Technology Center for Agriculture, Forestry and Fisheries, 7549-1 Yoshikawa, Kibichuo-cho, Okayama 716-1241, Japan.
Aya
A
Hatano-Iwasaki
Ken'ichi
K
Ogawa
D017360:Arabidopsis / Q000201:enzymology / Q000235:genetics* / Q000502:physiology; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism; D017796:Caulimovirus / Q000235:genetics; D003080:Cold Temperature; D035264:Flowers / Q000201:enzymology / Q000235:genetics / Q000502:physiology; D015971:Gene Expression Regulation, Enzymologic; D018506:Gene Expression Regulation, Plant; D017343:Genes, Plant; D005721:Glutamate-Cysteine Ligase / Q000235:genetics / Q000378:metabolism*; D005978:Glutathione / Q000378:metabolism; D010084:Oxidation-Reduction; D018384:Oxidative Stress; D030821:Plants, Genetically Modified / Q000201:enzymology / Q000235:genetics / Q000502:physiology; D011401:Promoter Regions, Genetic; D018749:RNA, Plant / Q000032:analysis / Q000235:genetics; D012639:Seeds / Q000201:enzymology / Q000235:genetics / Q000502:physiology*; D014158:Transcription, Genetic
D029681:Arabidopsis Proteins; D018749:RNA, Plant; D005721:Glutamate-Cysteine Ligase; C493655:Gsh1 protein, Arabidopsis; D005978:Glutathione