Expression of a cyanobacterium plasmamembrane Na+/H+ antiporter in rice to enhance its salt tolerance

• Main Authors: Cheng, Shin-Yi, 鄭欣怡
• Other Authors: 古森本
• Format: Others
• Language: zh-TW
• Online Access: http://ndltd.ncl.edu.tw/handle/78128917719157983066

碩士 === 國立嘉義大學 === 生物農業科技學系碩士班 === 96 === Under saline conditions, cyanobacteria use plasmamembrane Na+/H+ antiporter to transport Na+ out of cell. This adaptive mechanism allows cyanobacteria to reduce the accumulation of Na+ and its harmful effects in the cell, allowing normal metabolic activities in the cytoplasm to proceed. In this study, a cyanobacterial Na+/H+ antiporter gene (nhaS4) was introduced into rice via Agrobacterium-mediated transformation. Molecular analyses showed the cyanobacterial gene is integrated into the genome of transgenic rice and expressed constitutively in various tissues. Physiological analyses exhibited no significant differences between transgenic and non-transgenic rice in the contents of various ions when grown under normal (low salt) conditions. However, under salt (100 mM NaCl) conditions, transgenic rice accumulated 24% and 70% less (P<0.01) Na+ in the root and leaf, respectively, as compared to non-transgenic rice. In contrast, no differences in Cl- content were found between the two genotypes under normal or salt conditions. These results demonstrated the specificity of this transporter against Na+ and its effectiveness in reducing the accumulation of Na+ in the cell. Furthermore, transgenic rice possessed a higher capability to absorb K+ under saline conditions, allowing the plants to maintain a higher K+/Na+ ratio in the cell. Most importantly, the degrees of inhibition by NaCl on growth of seedlings and leaf photosynthesis were 12-15% lower (P<0.05，P<0.01) in transgenic than in non-transgenic rice. Taken together, this study clearly demonstrates that the cyanobacterium Na+/H+ antiporter gene (nhaS4) can be properly expressed in rice and effectively prevent Na+ accumulation in the cell for enhanced salt tolerance. A similar approach can also be applied to other crops for the improvement of yield and quality in saline environments.