水稻循环光合磷酸化(CPSP)的基因型差异及形成机制

Photosynthesis provides the material basis of crop yield formation, 90-95 precent of crop dry mass comes from photosynthate. ATP supply is usually the key limting factor of photosynthesis, insufficient ATP is frequently supplied by cyclic-photophosphorylation (CPSP); but the researches of CPSP in rice were amlmost. In this proposal, the germplasm resources of rice in early, medium and late seasons will be used as research objects,the combination of modern and traditional techniques and corroboration of detections in vivo and vitro will be adopted.The genotypic differences, seasonal and diurnal variations or dynamic observations in different growth stages of their CPSP will be investigated to reveal the occurrence regularities of rice CPSP. The relations between CPSP differences of rice and habitat factors will be analyzed to seeking for the key influencing factors. Moreover, rice genotypes with the significant differences of CPSP will be selected as the experiment materials, the effects of key habitat factors, CPSP inhibitors and accelerators on rice CPSP and the related physiological and biochemical processes will be conducted to clarify the formation mechanism of genotypic differencs in rice CPSP. The project approval and successful completion of this research will supply the excellent germplasm resources for the breeding of high photosynthetic efficiency in rice, and provide the theoretical basis and technical supports for improving the photosynthetic efficiency of rice with biotechnology or other techniques and establishing the cultivation system of high photosynthetic efficiency in rice.

光合作用是作物产量形成的物质基础，90%-95%的作物干重来自光合产物。ATP供应常常是限制光合作用的重要因素，不足的ATP需要通过循环光合磷酸化(CPSP)来供给，而目前有关水稻CPSP的报道较少。本研究以不同类型(早季、中季和晚季)稻种资源为对象，采用传统和现代技术相结合、活体和离体检测相印证的手段，进行水稻CPSP的基因型差异、季节和日变化及生育时期的动态观测，揭示水稻CPSP的发生规律；通过水稻CPSP差异与生境因子关系的分析，寻求影响水稻CPSP的关键生境因子；并以CPSP存在显著差异的水稻基因型为材料，开展关键生境因子、CPSP抑制剂和促进剂对水稻CPSP及相关生理生化过程的调控研究来探明水稻CPSP基因型差异的形成机制。本研究的立项和顺利完成将为水稻高光效育种提供优异的种质资源，为运用生物技术或者其它手段改良水稻光合效率和建立水稻高光效栽培体系提供理论基础与技术支撑。

作物产量形成的90%-95%的干物质来源于光合作用产物。ATP供应通常是限制光合作用的重要因素，不足的ATP大多由循环光合磷酸化(CPSP)来提供。本项目以随机选择的102份生育期基本一致且被育种家认定为综合性状良好的水稻种质为材料，采用传统和现代技术相结合与活体和离体检测相印证的方法，解析了水稻CPSP的基因型差异及形成机制，为水稻高光效育种提供优异的种质，为改良水稻光合效率和建立水稻高光效栽培体系提供理论基础与技术支撑。主要研究结果有：(1)、水稻种质间的CPSP存在大于叶绿素荧光参数间的极显著基因型差异，可作为衡量水稻光合特性遗传差异的重要指标。(2)、筛选到了一批光合性状特异的水稻种质，尤其是高CPSP的D57B和低CPSP的高光B。(3)、早稻品种注重光合色素的合成和光合单位的构建；晚稻品种强调光合机构各组分间的协调和整体效率的提高，尤其是偶联CPSP的PSI活性。(4)、水稻CPSP能力随生育时期推进而升高，差异主要发生在始穗至灌浆期，与叶绿素荧光参数Fo、Fm、Y(NPQ)、NPQ和ETR密切相关。(5)、水稻CPSP能力是应对不良环境的一个敏感且重要的调节途径，光强和CO2浓度尤为关键，温度和水分其次。(6)、高CPSP水稻具有高单位叶面积叶绿素(特别是叶绿素b)含量和ms-DLE快相，使得Fm、F、Y(II)和质子动力势的膜电位较高及PSII水氧化时的质子释放较多，促进等蛋白类囊体的光合磷酸化ATP合成速率较高，提高线性电子传递和围绕PSI的循环电子传递。(7)、高CPSP水稻具有高CA酶活性和低PGK活性，促进CO2向Rubisco扩散，提高CO2的固定速率，但限制1,3-二磷酸甘油酸(DPGA)的生成。(8)、无论在叶片、茎鞘还是颖壳中，高CPSP水稻单个细胞中的叶绿体数目和发育程度均优于低CPSP水稻。(9)、造成水稻CPSP较低的可能分子机制是叶绿体基因ycf3的mRNA第2个内含子无法正常剪接和部分叶绿体基因的mRNA剪接效率降低，减少PSI亚基PsaD和PsaE，抑制PSI单体聚合，导致PSI功能异常和低循环电子传递效率。