RES2（Polygalacturonase）参与四分体果胶壁降解影响温敏不育系育性转变机制的研究

温敏雄性不育系是“两系”杂交水稻育种的重要材料。最新的研究认为，温敏不育系低温恢复育性是通过减缓发育来实现的。然而，减缓发育是如何保护缺陷小孢子并使其恢复育性的机制尚不清楚。我们前期研究发现四分体果胶壁降解延迟的res2能恢复温敏突变体rvms-2的育性。而且还发现许多温敏突变体的小孢子败育过程都发生在四分体释放后期。因此推测：对四分体释放后期缺陷小孢子的保护可能是温敏突变体育性恢复的关键。本项目将利用细胞学及遗传学等手段，首先通过寻找直接调控RES2的上游转录因子揭示四分体释放前后果胶壁降解与花粉壁沉积的时序关系；其次分析在四分体释放后期延迟果胶壁或胼胝质壁降解对温敏突变体育性的影响；另外探究温敏突变体在四分体释放后期败育的机制，最终阐明在四分体释放后期保护温敏突变体缺陷小孢子并使其恢复育性的机制。本项目能进一步揭示植物温敏育性的转换机制，为改良两系法杂交水稻育种提供理论依据。

The thermo-sensitive genic male sterile line (TGMS) is the key of hybrid rice seed production in “two line” method. The latest research shows that the fertility restoration of TGMS lines via the slowing development. However, how slow development relieves the stress in TGMS lines to protect defective pollen survival remains unclear. Our study has found that the functional mutation of RES2 results in the delay of tetrad pectin wall degradation and restores the fertility of rvms-2. In addition, the pollen of many TGMS lines aborts occurred in the later stage of tetrad release. Therefore, we speculate that the fortification of tetrad wall in the later stage of tetrad release protecting defective microspores is the key to the sterility-fertility conversion of TGMS lines. In this project, we will use cytological and genetic methods to reveal the timing relationship between pectin wall degradation and pollen wall deposition around the tetrad release by identifying the upstream transcription factor of RES2; Then, we will analyze the effect of pectin wall or callose wall degradation delay in the later stage of tetrad release on the fertility conversion of TGMS lines; Subsequently, we will explore the mechanism of of defective microspores abortion of TGMS lines in the later stage of tetrad release. Finally, we try to substantiate the mechanism of protecting the defective microspores of TGMS lines in the late stage of tetrad release and restoring fertility. This project can further reveal the mechanism for the sterility-fertility conversion of TGMS lines and provide theoretical basis for the improvement of two-line hybrid rice breeding.