Faculty of Agriculture, Iwate University, 3-18-8 Ueda, Morioka, 020-8550 Japan.
Graduate School of Agricultural Science, Tohoku University, 468-1 Aramaki-Aoba, Aoba-ku, Sendai, 980-8572 Japan.
Plant Cell Physiol. 2021 Mar 25;62(1):156-165. doi: 10.1093/pcp/pcaa149.
Chloroplast glyceraldehyde-3-phosphate dehydrogenase (GAPDH) limits the regeneration of ribulose 1,5-bisphosphate (RuBP) in the Calvin-Benson cycle. However, it does not always limit the rate of CO2 assimilation. In the present study, the effects of overproduction of GAPDH on the rate of CO2 assimilation under elevated [CO2] conditions, where the capacity for RuBP regeneration limits photosynthesis, were examined in transgenic rice (Oryza sativa). GAPDH activity was increased to 3.2- and 4.5-fold of the wild-type levels by co-overexpression of the GAPDH genes, GAPA and GAPB, respectively. In the transgenic rice plants, the rate of CO2 assimilation under elevated [CO2] conditions increased by approximately 10%, whereas that under normal and low [CO2] conditions was not affected. These results indicate that overproduction of GAPDH is effective in improving photosynthesis under elevated [CO2] conditions, although its magnitude is relatively small. By contrast, biomass production of the transgenic rice plants was not greater than that of wild-type plants under elevated [CO2] conditions, although starch content tended to increase marginally.
叶绿体甘油醛-3-磷酸脱氢酶（GAPDH）限制卡尔文-本森循环中核酮糖 1,5-二磷酸（RuBP）的再生。然而，它并不总是限制 CO2 同化的速率。在本研究中，通过共过表达 GAPDH 基因 GAPA 和 GAPB，分别将 GAPDH 的活性提高到野生型水平的 3.2 倍和 4.5 倍，研究了 GAPDH 过表达对高[CO2]条件下 RuBP 再生限制光合作用的 CO2 同化速率的影响。在转基因水稻中，高[CO2]条件下的 CO2 同化速率提高了约 10%，而正常和低[CO2]条件下的 CO2 同化速率没有受到影响。这些结果表明，尽管 GAPDH 的过表达提高光合作用的幅度相对较小，但在高[CO2]条件下，过表达 GAPDH 对于提高光合作用是有效的。相比之下，在高[CO2]条件下，转基因水稻的生物量产量并不高于野生型水稻，尽管淀粉含量略有增加。
