Tobacco Transformed With Sense CaGPAT Gene Alleviates PSⅡ Photoinhibition Under High Temperature Stress

Tobacco transformed with sense CaGPAT gene and wild tobacco were taken as materials in our research. We investigated the changes of lipids composistion in thylakoid membrane, effects of high temperature on photosynthetic rate and characteristic of chlorophyll a fluorescence of transgenic tobcco and the recovery process after high temperature stress.In order to study the function of GPAT gene better, we transfered the gene into sweet pepper by A trumefaciens-mediated leaf disk tranformation using cotyledon of"zhongjiao 2"as explants. Now the transgenic sweet pepper plants have been achieved. The main results are as follows:1. The saturated extent of MGDG, SQDG, DGDG and PG in thylakoid membrane of transgenic tobacco plants increased generally. However, the saturated extent of MGDG increased obviously by 16.2%.2. After high temperature stress, Pn of transgenic tobacco decreased obviously less than wild type, which indicated that the photosynthetic capability of transgenic tobacco was higher than that of wild type under high temperature stress.3. Under high temperature stress, Fv/Fm, Fv'/Fm', qP andΦPSâ…¡of transgenic tobacco and wild type decreased remarkblely, but the extent of decrease in transgenic tobacco was smaller than that in wild type, which indicated that high temperature tolerance of transgenic tobacco PSâ…¡was higher than that of wild type.4. In the recovery process after long time high temperature stress, there were no obviously dictinct changes of Wk between transgenic tobacco and wild type, but Vj, MO, Fv'/Fm'and qP of transgenic tobacco recovered faster. It suggested that changes of thylakoid membrane lipids in transgenic tobacco had no effect on the recovery of oxygen evolution complex. Nonetheless, it promoted the recovery of the capability of harvesting light and electron tansport in acceptor side. Fv/Fm and PI of transgenic tobacco also recovered faster, which indicated that the total PSII performance of transgenic tobacco could recovery faster.5. Transgenic sweet pepper were successfully achieved in our study, and we also have obtained an effective sweet pepper transformation system: buds induction medium is MS+5mg/L 6-BA+1mg/L IAA+10mg/L AgNO₃; bud elongation medium is MS+1-2mg/L GA3+1mg/L IAA; Root formation medium is MS+0.5mg/L IAA. The advantages of this protocol are low cost of chemicals and simple operation. But lower transformation rate is the disadvantage. Therefore, to improve it surely needs lots of successive work.