过表达RuBP再生关键酶基因改善小麦在波动光下光能利用率的机制研究

The development of yield potential genetic improvement in wheat varieties largely depends on the further advance of photosynthetic performance. Existing high photosynthetic efficiency breeding goal is aimed at a steady light environment setting, but the light intensity on surface of wheat leaf in the field is fluctuating all the time. We found that 85% of the radiation time of wheat leaf in the field is in duration of less than 5 minutes the fluctuating light. The leaf light energy use efficiency in fluctuating light is 40% less than that in continuous light, while the over-expression of RuBP carboxylation process key enzymes, SBPase, significantly improved the light energy use efficiency in fluctuating light, but it does not work, when the Rubisco, the key enzymes of RuBP regeneration process, the key enzyme of RuBP carboxylation, is over-expressed. This study attempts to clarify the mechanism that over-expression SBPase improves the utilization efficiency of fluctuation light, and further explore whether the utilization efficiency of fluctuating light would be increased by over-expression of two keys enzymes of RuBP regeneration, and whether the maximum photosynthetic capacity and light use efficiency of fluctuating light woud be improved simultaneously by over-expressing the Rubisco and SBPase, which would further improve the photosynthetic characteristics of wheat. This study will deepen the mechanism study of wheat high photosynthetic efficiency, create high photosynthetic efficiency of wheat germplasm resources, and also provide more targets for the screening of high photosynthetic efficiency of wheat varieties.

小麦叶片光合性能的提高是我国高产小麦品种选育取得新进展的重要保证。现有的高光效育种目标都是针对稳态光环境设立的，而我们观察到田间小麦叶片85%的时间处于波动光下。波动光下叶片的光能利用率比持续光下低40%。如何减少这一巨大光合损失，目前尚未见报道。我们近期工作表明，过表达RuBP再生关键酶SBPase可以显著提高波动光的利用效率，从而提高单株产量，但过表达RuBP羧化关键酶Rubisco则不能。本研究试图通过光合限制因素分析，酶活和代谢产物定量检测，阐明过表达SBPase提高波动光利用效率的机制；并进一步探索能否通过过表达两个RuBP再生关键酶进一步提高波动光利用效率，以及能否通过同时过表达Rubisco和SBPase同时提高最大光合能力和波动光利用效率，从而提高小麦光合性能。本研究将从一个新的角度寻找改善小麦光合性能的途径，为创建高光效小麦种质资源和高光效小麦新品种的筛选提供理论支持。

小麦叶片光合性能的提高是我国高产小麦品种选育取得新进展的重要保证。现有的高光效 育种目标都是针对稳态光环境设立的，而我们观察到田间小麦叶片大多数时间处于波动光下。 波动光下叶片的光能利用率比持续光下低40%。减少这一巨大光合损失，可以为小麦高产育种提供新途径。此研究中我们在小麦中过表达TaS.1与TaRs.1基因，并通过杂交获得同时过表达TaS.1与TaRs.1基因的小麦植株，在两种动态光环境中检验了小麦的光合碳同化速率。第一是弱光适应叶片转入强光的光合启动过程；二是强光适应叶片转入强弱光交替的波动光。结果表明，过表达TaS.1基因没有提高光合启动速度，但是提高了波动光下的光能利用效率。过表达TaS.1基因提高了光合启动速度，同时提高了波动光下的光能利用效率。同时过表达TaS.1与TaRs.1基因没有进一步提高光合启动速率，但是进一步提高了波动光下的光能利用效率。这表明，在光合启动阶段以及强光转波动光后光合作用的限制因素不同。本研究加深了我们对动态光下光合碳同化的理解，而且为小麦高产和高光效育种提供了新思路。