The eighth generation of PEPC transgenic rice and an untransformed rice cultivar (Oryza sativa L. subsp. japonica cv. Kitaake) were need to study photosynthetic rate and chlorophyll fluorescence parameters by applying the stable and radioactive carbon isotope. The results showed that the germplasm of PEPC transgenic rice was a C3 plant with certain C4 photosynthetic characteristics.The light saturation photosynthetic rate of transgenic rice was higher than that of untransformed rice. In the treatment with high light intensity (3 h) and methyl viologen (MV), a photooxidative reagent, the PSⅡ photochemical efficiency (Fv/Fm) and photochemical quenching (qP) of transgenic PEPC rice were decreased less, while the non-photochemical quenching (qN) were increased more as comparison with those of untransformed rice. The higher activities of antioxidative enzymes superoxide dismutase (SOD) and peroxidase (POD) in transgenic rice plants led to a lesser accumulation of endogenous active oxygen (O2．- , H2O2). As a result, the malondialdehyde (MDA, a product of membrane-lipid oxidation) content was reduced. Compared with the previous generations, the germplasm of PEPC transgenic rice has been steady in genetic, which may become a new germplasm resource in the breeding for high photosynthetic efficiency.
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