过表达番茄GDP-L-半乳糖磷酸酶基因提高烟草抗MV诱导的氧化胁迫能力

为了探讨番茄GDP—L-半乳糖磷酸酶对烟草抗坏血酸（AsA）含量及抗氧化能力的影响，从番茄叶片中分离了GDP-L-半乳糖磷酸酶基因（LeGGP），并转入到烟草中。以野生型（WT）和转正义LeGGP烟草株系T1-3和T1-15为试材，测定了甲基紫精（MV）处理下AsA、脱氢抗坏血酸（DHA）、H2O2、O2-和叶绿素含量、抗坏血酸过氧化物酶（APX）活性、光合速率和叶绿素荧光参数等。Northem杂交分析表明LeGGP的表达受MV的诱导，在MV处理下，野生型烟草的离体叶圆片发生比转基因烟草更严重的光漂白，转基因烟草的AsA含量及清除H2O2和O2-的能力明显强于野生型，过表达LePGG胀高了烟草的生长量。并且转基因烟草比野生型具有更高的净光合效率（Pn）和光系统Ⅱ（PSII）最大光化学效率（眠）。结果表明，LeGGP的过表达有助于提高烟草AsA含量及抗氧化胁迫能力。

Overexpression of Tomato GDP-L-Galactose Phosphorylase Gene Enhanced Tolerance of Transgenic Tobacco to Methyl Viologen-Mediated Oxidative Stress

In order to investigate the effect of tomato GDP-L-galactose phosphorylase （GGP） on ascorbate （AsA） content of transgenic tobacco and tolerance to oxidative stress, tomato GDP-L-galactose phosphorylase gene （LeGGP） was introduced into tobacco. WT, sense-transgenic lines T1-3 and T1-15 of tobacco were used to measure the contents ofAsA, dehydroascorbate （DHA）, hydrogen peroxide （H2O2）, O2-, and chlorophyll, activity of ascorbate peroxidase （APX）, photosynthetic rate and chlorophyll fluorescence parameters under methyl viologen （MV） treatment. Northem blot analysis confirmed that the expression of LeGGP was induced by MV. The content of AsA, the capability for scavenging H2O2 and O2- of the transgenic tobacco plants were distinctly higher than those of WT under MV treatment. Overexpression of LeGGP in tobacco improved growth of seedlings. Under MV treatment, more serious bleaching was observed in the leave of WT plants. The net photosynthetic rate （Pn） and the maximal photochemistry efficiency of PSII （Fv/Fm） in the transgenic plants were higher than those of WT. These results indicated that overexpression of LeGGP increased AsA content and enhanced tolerance of transgenic tobacco plants to MV-induced oxidative stress.