ABSTRACT

The capacity for regeneration of the substrate for Rubisco, ribulose 1,5-bisphosphate (RuBP), is one of the candidates for the bottleneck in photosynthesis in transgenic rice plants with overproduction of Rubisco. As the overproduction of chloroplast glyceraldehyde-3-phosphate dehydrogenase (GAPDH) was suggested to slightly enhance RuBP regeneration capacity, transgenic rice plants with co-overproduction of Rubisco and GAPDH were generated to improve photosynthesis. The amount of Rubisco increased by 8% to 18%, whereas GAPDH activity increased to 2.1- to 3.2-fold that of the wild-type. However, the rate of CO₂ assimilation did not increase under conditions of high irradiance and different [CO₂] partial pressures. The possibility that photosynthesis in the co-overproduced plants was co-limited by Rubisco, GAPDH, and other unknown factors is discussed.

摘要

Rubisco 的底物 1,5-二磷酸核酮糖 (RuBP) 的再生能力是 Rubisco 过量生产的转基因水稻植物光合作用瓶颈的候选者之一。由于叶绿体 3-磷酸甘油醛脱氢酶 (GAPDH) 的过量生产被认为略微增强了 RuBP 的再生能力，因此产生了具有 Rubisco 和 GAPDH 共同过量生产的转基因水稻植物以改善光合作用。Rubisco 的量增加了 8% 到 18%，而 GAPDH 活性增加到野生型的 2.1 到 3.2 倍。但是，CO的速率₂同化没有CO高辐照度和不同的条件[下增加₂] 分压。讨论了共同过量生产植物中的光合作用受到 Rubisco、GAPDH 和其他未知因素共同限制的可能性。