High Light Tolerance is Enhanced by Overexpressed PEPC in Rice under Drought Stress

Overexpression of phosphoenolpyruvate carboxylase(PEPC) gene in transgenic rice to improve photosynthesis and stress resistance have brought extensive interest in the world.Our previous report proved that the overexpressed PEPC alleviate drought stress inhibition on photosynthesis.In the present research,photosynthetic light curve,chlorophyll a fluorescence pa-rameters,pigment content and reactive oxygen metabolism were studied under drought stress at flowering stage in two lines of PEPC transgenic rice plants.The results showed that under drought especially severe drought stress,net photosynthetic rate de-creased dramatically under high photosynthetic active radiation(PAR) in wild type untransformed rice,while maintained un-changed in PEPC transgenic lines under high PAR even more than 1 200 μmol m-2 s-1;and the photochemistry activities(Fv/Fm,ΦPSⅡ,and qP) decreased less under drought stress in both the PEPC transgenic lines.These indicated PEPC enhanced the photoin-hibition tolerance of rice under drought stress.The higher zeaxanthin content under drought stress made the PEPC transgenic rice leaves disperse more light energy as heat,thus decreased the producing rate in PSII.At the same time,the SOD,POD,and CAT activities were higher in PEPC transgenic rice plants under drought stress.These enzymes could effectively diminished the reactive oxygen species and reduced the membrane lipid peroxidation.