Enhancement of Rice Leaf Photosynthesis by Crossing between Cultivated Rice, Oryza sativa and Wild Rice Species, Oryza rufipogon(Crop Physiology and Ecology)

概要

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To study whether wild rice species have genes that may increase potential photosynthetic capacities of rice cultivars, we generated BC_2 populations by reciprocally backcrossing Oryza rufipogon (W630) with O. Sativa cv. Nipponbare and IR36; N-BC_2 populations and IR-BC_2 populations, respectively. We measured the oxygen evolution rates (OER) of single leaves under saturating light and CO_2 as the maximum photosynthetic rates and the contents of ribulose 1,5-bisphosphate carboxylase/oxygenase (Rubisco) and Rubisco activase. Several lines in each BC_2 population had significantly higher OERs than parental cultivars, and 14〜25% of plants in BC_2 populations had higher OERs than the highest values in parental cultivars. The highest OERs in BC_2 populations were about 60% higher than average OERs in parental cultivars. The BC_2 populations contained 30〜40% more Rubisco than parental cultivars. The Rubisco activase contents in N-BC_2 populations were 15〜30% lower than that in Nipponbare. Cytoplasms derived from O. rufipogon and O. sativa had different effects on the contents of Rubisco and Rubisco activase particularly in N-BC_2 populations. In several lines of each BC_2 population the OERs had positive correlations with the contents of Rubisco and/or Rubisco activase. These results suggest that O. rufipogon can be used as a source of germplasm to enhance the photosynthetic capacity of O. sativa.