灌浆期夜间高温增强水稻线粒体跨膜电子传递的代谢机制

High night temperature has become a primary weather disaster for rice yield and quality, grain-filling and stability of good quality. Our previous studies showed that high night temperature does not directly affect the expression of the genes related to rice grain-filling and quality, but enhances the expression of the genes involved in mitochondria transmembrane electron transfer and oxidation process, which lead to pH value vary and disequilibrated oxidation in cell. The functions of the genes involved in endosperm cells development and filling, proteins synthesis and degradation, starch accumulation and solution are further affected by the variation of pH value and disequilibrated of oxidation, and rice yield and quality are finally limited. However, how the signals of high temperature stresses transfer to membrane and disequilibrium of acid-base and oxidation, are poorly understood. In present study, we are going to analyze the metabolics dynamic changes on the heat-tolerant and -sensitive rice lines under high night temperature stress at early milky stage, and compare the different metabolins and its metabolic pathway between two materials., Furthermore, the conjoint analysis of the dynamic change of the metabolins contents and the identified signal proteins’ expressed model obtained in our previous study will be proceeded, and finally to elucidate the key metabolins and its metabolic pathway on signals transfer of high night temperature. The results will supply reliable metabolic markers for rice physiologic breeding on heat-tolerant traits, and establish essential research bases for accurate measure on preventing damage by high temperature stresses at rice milky stage.

灌浆期夜间高温已成为制约水稻产量和品质、影响籽粒灌浆充实和优质稳定性的主要气候灾害，但本项目组已有研究表明其并非直接影响水稻粒重和品质性状的基因表达，而是先增强线粒体跨膜电子传递和细胞氧化相关的基因表达，导致质膜内外pH值变化、胞内氧化失衡；进而影响下游与胚乳细胞发育与充实、蛋白合成与降解、淀粉积累与支解等相关基因的功能，最终造成粒重降低和品质变劣。高温胁迫信号由哪些代谢分子或复合体、怎样传递给质膜并引发酸碱和氧化失衡？亟待阐明。本项目拟以所选育的耐热和热敏感近等基因系为材料，分析它们应答灌浆期夜间高温的代谢组动态变化，比较耐热和热敏感水稻纯系间的差异代谢物及其代谢途径，在已鉴定参与信号传导的蛋白质及其表达模式的基础上，结合差异代谢物含量的动态变化过程及其代谢途径，系统揭示高温信号传递至质膜的关键代谢分子及其代谢途径。研究结果可为开发防范水稻灌浆期高温热害的抗逆技术措施提供必要基础。

以本项目组所选育的耐热和热敏感近等基因系为材料开展研究，研究结果弄清了耐热和热敏感水稻纯系应答灌浆期夜间高温的代谢组动态变化及其差异，深入揭示了水稻应答灌浆期夜间高温的关键代谢物及其代谢途径，探明了水稻应答灌浆期高温的代谢机制涉及信号传导、氧化作用、物质的生物合成与降解等生物学过程，为开发防范水稻灌浆期高温热害的抗逆技术措施提供了理论支撑，为进一步深入阐明水稻响应灌浆期高温胁迫的机制奠定了基础。进一步以第三方独立样本即筛选鉴定得到的3个灌浆期耐热水稻纯系品种、3个灌浆期热敏感水稻纯系品种为试材，鉴定了灌浆期昼夜高温诱导的差异积累代谢物，分析了这些差异代谢物的生物学功能，结合耐热和热敏感近等基因系的研究结果综合分析，结果显示谷氨酰胺和焦谷氨酸在应答夜间高温、昼夜高温均表现出相同的变化模式，同时谷氨酰胺在高温胁迫响应中作为信号分子和其它含氮代谢物合成的氮供体、焦谷氨酸位于γ-谷酰基循环中与外质体氧化还原信号的产生有关。研究结果阐明了水稻颖果中的谷氨酰胺和焦谷氨酸在水稻高温胁迫响应中起重要作用、是高温信号传递至线粒体质膜的关键代谢分子、可作为筛选灌浆期耐热性水稻种质的代谢标志物，水稻颖果中谷氨酰胺和焦谷氨酸的积累增幅是水稻耐热性育种的有效分子标记。项目实施过程中，培养了博士1人、硕士2人，已发表SCI论文3篇，获得授权国家发明专利2件，育成通过省级品种审定的水稻灌浆期耐热优质高产新品种1个。