Studies on the Enhancement of Salt Tolerance of Rice (Oryza sativa L.) Seedlings by Overexpression of Glutathione Reductase from Marine Macroalga Ulva fasciata Delile

• Main Authors: Kai-Chih Lin, 林楷智
• Other Authors: none
• Format: Others
• Language: zh-TW
• Published: 2014
• Online Access: http://ndltd.ncl.edu.tw/handle/tnagrq

碩士 === 國立中山大學 === 海洋科學系研究所 === 102 === This study was to examine whether the Agrobacterium-mediated overexpression of a marine macroalgal glutathione reductase (UfGR; NCBI number DQ286546.1) of Ulva fasciata Delile in Japonica rice (Oryza sativa L. cv. Tainung 67, TNG67) improves the tolerance of rice to salt stress. Using the transformation of ubiquitin:: UfGR + 35S::GFP, the hydroponically grown seedling (4-leaf age) of transgenic line with homozygous gene expression (T2) were used to determine the GR activity and their responses to salt challenge (150 mM NaCl). Transgenic lines, OE-UfGR-1 and OE-UfGR-3 that GR specific activity is higher than wild type showed higher survival ratio after recovery to normal condition without NaCl. Under 150 mM NaCl conditions,the decrease in effective PSII activity (Fv/Fm), maximum PSII activity (Fv''/Fm'') and the contents of chlorphyll a, chlorophyll b, and carotenoids in the transgenic lines is lower than those in wild type. Transgenic lines showed a lower H2O2 and malondialdehyde (MDA, lipid peroxidation indiicator) contents following NaCl treatment, but the increae in proline contents is higher in transgenic lines as compared to the wild type after NaCl treatment. The GR specific activity of transgenic lines could be induced under NaCl treatment and the induction is higher in transgenic lines, while the specific activity of ascorbate peroxidase (APX) and catalase (CAT) showed a similar trend. Glutathione (GSH) content, GSH/oxidized glutathione (GSSG) ratio, ascorbate (AsA) content, and AsA/dehydroascorbate (DHA) ratio were highly induced by NaCl treatment, particularly in the transgenic lines. But, the increae in Na+ content as well as the decrease in K+ contents and K+/Na+ ratio by NaCl treatment were same between wild type and transgenic lines. It could be concluded that overexpression of UfGR effectively enhances the tolerance of rice to slat stress via the enhancement of ascorbate–glutathione cycle for the reduction of oxidative damage under salt stress, but not the regulation of K+ and Na+ content.