Role of Tic40 in Male Sterility in Oilseed Rape

内共生细胞器、线粒体和质体需要在翻译后过程中从细胞质中输入大部分蛋白质成分。多亚单位蛋白质转运机制分别称为叶绿体外膜转运子(TOC)和内膜转运子(TIC)，负责前蛋白的识别和转运。Tic40是转位蛋白的一个重要亚基，定位于Tic复合体的基质侧，在那里它被认为是将分子伴侣招募到转位通道中前蛋白的出口部位。然而，在模式植物拟南芥中进行详细的生理和功能分析是不可能的，因为单个Tic40编码基因的功能突变丢失会导致严重的淡绿色多效性表型，这排除了具体分析的可能性。在甘蓝型油菜(Brassica napus，油菜)近缘种中，存在多个Tic40基因产物。进一步证明了BnaCTic40亚型作为油菜雄性不育恢复基因的功能，从而实现了这一计划的两个目标。首先，详细了解Tic40的生理和机制功能。其次，我们将了解Tic40在油菜育性恢复中的作用，这是改进育种过程的重要特征。

The endosymbiotic organelles mitochondria and plastids need to import most of their protein constituents from the cytosol in a posttranslational process. Multisubunit protein transport machineries named translocon at the outer and inner envelope of chloroplasts (TOC and TIC), respectively, are responsible for preprotein recognition and translocation. Tic40 is a prominent subunit of the translocon and localizes to the stromal side of the Tic complex, where it is supposed to recruit molecular chaperones to the exit site of preproteins from the translocation channel. A detailed physiological and functional analysis in the model plant Arabidopsis thaliana is, however, not possible since a loss of function mutant of the single Tic40 coding gene results in a severe pale green pleiotropic phenotype, which precludes specific analysis. In the related species Brassica napus (oilseed rape), multiple Tic40 gene product exist. One isoform BnaCTic40 was further shown to function as a restorer gene for male sterility in oilseed rape, thereby allowing to achieve two aims with this proposal project. Firstly, to get a detailed insight into the physiological and mechanistic function of Tic40. Secondly, we will understand the role of Tic40 in fertility restoration in oilseed rape, an important feature to improve the breeding process.