Yu, Le;Liu, Yonghai;Tong, Jianhua;Ding, Junhui;Wang, Ruozhong;Peng, Changlian;Xiao, Langta

Ding, Junhui; Wang, Ruozhong;[Peng, Changlian] S China Normal Univ, Coll Life Sci, Guangzhou 510631, Guangdong, Peoples R China;[Tong, Jianhua;Zhaoqing Univ, Coll Life Sci, Zhaoqing 526061, Peoples R China.; Xiao, Langtao] Hunan Agr Univ, Hunan Prov Key Lab Phytohormones & Growth Dev, Changsha 410128, Hunan, Peoples R China.

Grain chalkiness;Ascorbic acid;Abscisic acid;Jasmonic acid;Ric

Chalkiness is one of the key factors determining rice quality and price. Ascorbic acid (Asc) is a major plant antioxidant that performs many functions in plants. L-Galactono-1,4-lactone dehydrogenase (L-GalLDH, EC1.3.2.3) is an enzyme that catalyzes the final step of Asc biosynthesis in plants. Here we show that the L-GalLDH-overexpressing transgenic rice, GO-2, which has constitutively higher leaf Asc content than wild-type (WT) plants, exhibits significantly reduced grain chalkiness. Higher foliar ascorbate/dehydroascorbate (Asc/DHA) ratios at 40, 60, 80, and 100 days of plant age were observed in GO-2. Further investigation showed that the enhanced level of Asc resulted in a significantly higher ribulose-1,5-bisphosphate (RuBP) carboxylase/oxygenase (Rubisco) protein level in GO-2 at 80 days. In addition, levels of abscisic acid (ABA) and jasmonic acid (JA) were lower in GO-2 at 60, 80, and 100 days. The results we present here indicate that the enhanced level of Asc is likely responsible for changing redox homeostasis in key developmental stages associated with grain filling and alters grain chalkiness in the L-GalLDH-overexpressing transgenic by maintaining photosynthetic function and affecting phytohormones associated with grain filling. (C) 2015 Crop Science Society of China and Institute of Crop Science, CAAS. Production and hosting by Elsevier B.V.