线粒体DNA拷贝数量及其稳定对于维持细胞正常生理功能十分重要，其调控机制研究对于全面理解被子植物线粒体非孟德尔遗传机理具有重要的科学意义。甜瓜属线粒体表现为独特的父系遗传，是研究线粒体DNA拷贝数调控的重要作物。本项目拟在前期克隆并验证核酸外切酶DPD1对甜瓜属花粉线粒体DNA降解作用并发现拟核蛋白参与了线粒体DNA拷贝数调控的基础上，采用细胞学与iTRAQ蛋白质组学技术相结合的方法，研究甜瓜属植物不同发育时期花粉线粒体拟核蛋白的表达，分析拟核蛋白对线粒体DNA拷贝数的具体作用；并利用原生质体瞬时表达、组织原位杂交及转基因等技术，综合分析核酸外切酶DPD1与拟核蛋白对甜瓜属花粉内线粒体DNA拷贝数的调控机制。研究结果将揭示甜瓜属线粒体拟核蛋白的分子组成，鉴定调控甜瓜属线粒体DNA数量的关键因子，初步阐明甜瓜属线粒体DNA拷贝数调控的分子机制，为被子植物线粒体遗传的分子机理研究奠定基础。

Stability of mitochondrial DNA copy number in a cell is essential to maintain normal physiological function, and the study on the regulatory mechanism of mitochondrial DNA copy number has great significance for non-Mendelian inheritance of angiosperm mitochondria. Plants of the genus Cucumis show the unique paternal inheritance of mitochondria, which are an excellent system to study the regulatory mechanism of mitochondrial DNA copy number. Our preliminary study results showed that DPD1, an exonuclease directly engaged in the degradation of mitochondrial DNA and that the mitochondrial nucleoid proteins involved in the regulation of mitochondrial DNA copy number. Based on those results, the project herein adopts the method of cytology combined with proteomics, and applies iTRAQ technology to analyze the proteome expression of the mitochondrial nucleoid proteins during Cucumis pollen development, providing the evidence for the role of nucleoid proteins in the regulatory system for mitochondrial DNA copy number. And comprehensive analysis the function of DPD1 and nucleoid proteins within the pollen based on transient expression in protoplast, the situ hybridization and transgenic technology. Expected results would reveal the molecular composition of Cucumis mitochondrial nucleoids and clone the key genes up-regulated mitochondrial DNA copy number, and then preliminarily elucidate the regulatory mechanism of mitochondrial DNA copy number in Cucumis. This study would lay the groundwork for the study of molecular mechanism of mitochondrial inheritance in angiosperm.