Chlorophyllide-a Oxygenase 1 (OsCAO1) Over-Expression Affects Rice Photosynthetic Rate and Grain Yield
Hu Ping, Ma Jie, Kang Shujing, Li Sanfeng, Wu Xianmei, Zeng Longjun, Lu Caolin, He Rui, He Huiying, Shang Lianguang, Rao Yuchun, Zhu Xudong, Xiong Guosheng, Qian Qian, Guo Longbiao, Wang Yuexing
Leaf color and photosynthesis are important factors for rice growth and development. Hence, improving the photosynthetic rate is an effective approach for increasing rice yield. We isolated a gene, chlorophyllide-a oxygenase 1 (OsCAO1), which characterized a rice near-isogenic line named fgl (faded green leaf). Compared with its recurrent parent, Zhefu 802 (ZF802, an early-season indica rice variety), fgl had a faded green leaf color and lower chlorophyll (Chl) content, especially Chl b content. Furthermore, genetic and physiological analysis confirmed that leaf color was affected by the novel allele OsCAO1, which had a two-base pair deletion in the ninth exon. Subsequently, we over-expressed the OsCAO1 gene in ZF802. Interestingly, while OsCAO1 over-expression (OX) increased Chl b synthesis, the OX plants had a higher photosynthetic rate and heavier 1000-grain weight than ZF802. In conclusion, the novel allele OsCAO1 was involved in the positive regulation of leaf color, photosynthetic rate and rice yield.