Abstract: Introducing enzymes involved in C₄ photosynthesis into C₃ crops is supposed to enhance the photosynthesis and crop productivity. Several attempts have been made to transfer phosphoenolpyruvate carboxylase (PEPC) gene from maize into rice, however, the relation of photosynthetic capacity, productivity and stress tolerance in transgenic rice was not analyzed. In the present research, the productivity and photosynthesis in T₄ offspring of ppc gene overexpressed rice were investigated under drought stress. The results indicated that the yield increased by 28% and 42%, and the number of tillers increased by 27% and 40%, respectively, in two transgenic lines T1 and T2 compared with those of the wild type under upland cultivation. Under drought stress, the transgenic rice seedlings maintained higher photosynthesis (A), stomatal conductance (G_s) and water use efficiency (WUE), as well as higher superoxide dismutase (SOD) activity and lower malondialdehyde (MDA) content than the wild type. It is suggested that the overexpression of ppc gene in rice makes higher antioxidation ability under drought stress. In addition, the transgenic lines T1 and T2 exhibited higher proline content and lower increase of osmotic potential under drought stress, suggesting that the ppc gene transgenic rice has the higher osmoregulation ability than the wild type. The similar results were also found in the ex-periments treated by PEG-6000. Therefore, the present results suggested that, the ppc gene overexpressed rice confers higher photosynthesis and drought tolerance under drought stress, which is helpful to increase the number of tillers, then contribute to enhance the rice yield.

Key words: Rice, Phosphoenolpyruvate carboxylase (PEPC), Transgene, Drought