Overexpression of Heat Shock Factor Gene HsfA3 Increases Galactinol Levels and Oxidative Stress Tolerance in Arabidopsis.
Heat shock factors (Hsfs) are central regulators of abiotic stress responses, especially heat stress responses, in plants. In the current study, we characterized the activity of the Hsf gene HsfA3 in Arabidopsis under oxidative stress conditions. HsfA3 transcription in seedlings was induced by reactive oxygen species (ROS), exogenous hydrogen peroxide (H2O2), and an endogenous H2O2 propagator, 2,5-dibromo-3-methyl-6-isopropyl-p-benzoquinone (DBMIB). HsfA3-overexpressing transgenic plants exhibited increased oxidative stress tolerance compared to untransformed wild-type plants (WT), as revealed by changes in fresh weight, chlorophyll fluorescence, and ion leakage under light conditions. The expression of several genes encoding galactinol synthase (GolS), a key enzyme in the biosynthesis of raffinose family oligosaccharides (RFOs), which function as antioxidants in plant cells, was induced in HsfA3 overexpressors. In addition, galactinol levels were higher in HsfA3 overexpressors than in WT under unstressed conditions. In transient transactivation assays using Arabidopsis leaf protoplasts, HsfA3 activated the transcription of a reporter gene driven by the GolS1 or GolS2 promoter. Electrophoretic mobility shift assays showed that GolS1 and GolS2 are directly regulated by HsfA3. Taken together, these findings provide evidence that GolS1 and GolS2 are directly regulated by HsfA3 and that GolS enzymes play an important role in improving oxidative stress tolerance by increasing galactinol biosynthesis in Arabidopsis.
Systems and Synthetic Agrobiotech Center and PMBBRC, Gyeongsang National University, Jinju 660-701, Korea.
Chieun
C
Song
Systems and Synthetic Agrobiotech Center and PMBBRC, Gyeongsang National University, Jinju 660-701, Korea.|Division of Life Science, Gyeongsang National University, Jinju 660-701, Korea.
Woo Sik
WS
Chung
Systems and Synthetic Agrobiotech Center and PMBBRC, Gyeongsang National University, Jinju 660-701, Korea.|Division of Life Science, Gyeongsang National University, Jinju 660-701, Korea.
Chae Oh
CO
Lim
D017360:Arabidopsis / Q000235:genetics / Q000502:physiology*; D029681:Arabidopsis Proteins / Q000235:genetics*; D004268:DNA-Binding Proteins / Q000235:genetics*; D003991:Dibromothymoquinone / Q000378:metabolism; D004187:Disaccharides / Q000096:biosynthesis; D005700:Galactosyltransferases / Q000235:genetics*; D018506:Gene Expression Regulation, Plant / Q000187:drug effects; D000076249:Heat Shock Transcription Factors; D006360:Heat-Shock Proteins / Q000235:genetics*; D006861:Hydrogen Peroxide / Q000494:pharmacology; D018384:Oxidative Stress; D010940:Plant Proteins / Q000235:genetics*; D030821:Plants, Genetically Modified / Q000502:physiology; D017382:Reactive Oxygen Species / Q000378:metabolism; D036226:Seedlings / Q000235:genetics / Q000502:physiology; D014157:Transcription Factors / Q000235:genetics*; D015533:Transcriptional Activation
D029681:Arabidopsis Proteins; D004268:DNA-Binding Proteins; D004187:Disaccharides; C000620136:HSFA3 protein, Arabidopsis; D000076249:Heat Shock Transcription Factors; D006360:Heat-Shock Proteins; D010940:Plant Proteins; D017382:Reactive Oxygen Species; D014157:Transcription Factors; D003991:Dibromothymoquinone; C013536:6 beta-galactinol; D006861:Hydrogen Peroxide; D005700:Galactosyltransferases; C000614915:GolS1 protein, Arabidopsis; C000614916:GolS2 protein, Arabidopsis; C096645:inositol 1-alpha-galactosyltransferase
gene regulation; osmoprotectant; transcription factor; transgenic plant