Poster: Heavy Metals

Abs # 97: Characterization of Gene-expression Mechanism of Arabidopsis Glutatione S-transferase, AtGST1 and AtGST11, in Response to Aluminum (Al) Stress

Presenter:	Ezaki, Bunichi , bezaki@rib.okayama-u.ac.jp
Authors	Ezaki, Bunichi  (A)   Suzuki, Masakatsu  (A)   Motoda, Hirotoshi  (A)   Kawamura, Masako  (A)   Matsumoto, Hideaki  (A)
Affiliations:	(A): Research Institute for Bioresources, Okayama University

To characterize gene-expression mechanism by aluminum (Al) stress in plants, two Al induced Arabidopsis glutathione S-transferase (GST) genes, AtGST1 and AtGST11, were investigated. Approximately 1 kb upstream region of each gene was fused to a GUS reporter gene (pAtGST1::GUS and pAtGST11::GUS) and introduced into Arabidopsis. Constructed two transgenic lines show a time-dependent gene-expression in root and/or leaf regions with a different degree by Al stress. The AtGST1::GUS gene was induced after a short period of Al treatment (approximately 2 h exposure), while the AtGST11::GUS gene was induced by an approximately 8 h exposure. GUS staining experiment using Al treated young seedlings indicted that GUS activity of each line was increased in shoot rather than in root and suggested that there may be a deduced signaling system between root and shoot. GUS staining experiment using adult pAtGST11::GUS line also suggested the signal-transfer from roots to leaves for the gene-expression in leaf region. Our recent analyses furthermore suggest that a decrease of cytoplasmic Ca ions in the root region effects on the gene-induction of the pAtGST11::GUS by Al stress in the shoot region, suggesting that Ca ion is related in the deduced signal-transfer. For other tested stresses, such as cold stress, heat stress, metal toxicity and oxidative damages, the transgenic lines also showed an increase in the GUS activity, indicating that there is a common induction mechanism for these various stresses including Al stress. It was suggested that homology as well as differences in DNA sequences of these two promoters cause observed similarity as well as differences in their response to the tested various stresses.