甜瓜属线粒体基因组的父系遗传特性

Detection of the Paternal Mitochondrial Inheritance in Cucumis

为分析甜瓜属线粒体基因组的遗传特性,选取甜瓜属11个不同种植物为试验材料,采用成熟花粉DAPI压片染色方法结合树脂半薄切片MTG-DAPI双染色技术,观察花粉贴壁期和成熟期细胞中的线粒体分布。结果显示,所涉及的11种甜瓜属植物均同黄瓜一样,成熟花粉细胞生殖核周围或精细胞中存在线粒体DNA;而作为对照的南瓜和西葫芦的花粉细胞发育到成熟期时生殖核周围没有任何细胞器DNA。上述结果表明,甜瓜属植物线粒体DNA有可能通过花粉进行遗传和散布。这个结果将线粒体基因组父系遗传潜力特性扩展到甜瓜属,为进一步探究植物线粒体基因组的父系遗传机制奠定基础。

Molecular analyses of cytoplasmic DNA are useful tools for evaluating the systematic position of one genus. The determination of chloroplast and mitochondria inheritance is a pre-requisite for the use of organelle DNA. For the vast majority of angiosperm,mitochondria are maternally transmitted. However study showed that mitochondria of cucumber(Cucumis sativus L.)and melon(C. melo L.)are paternally transmitted. In order to study the unique model for organellar genetics,we detected the modes of mitochondrial inheritance of eleven different species in Cucumis by cytological observation here. Organellar DNA in mature pollen grains was observed by 4',6-diamidino-2-phenylindole(DAPI)fuorescence microscopy combined with the conventional'squash method'. And then mitochondrial DNA in premature and mature pollen grains was observed by 7 100 resin sections double-stained with DAPI and Mito traker green(MTG)fuorescence microscopy. All thirteen species were classified into two types based on the presence or absence of mitochondrial DNA in mature generative cells or sperm cells. Eleven species in Cucumis could be grouped together with cucumber,which only had mitochondrial DNA, while pumpkin and squash had neither mitochondrial nor plastid DNA. The presence or absence of mitochondrial DNA corresponded to paternal/biparental inheritance or maternal inheritance of mitochondrial. So the result revealed that all the species in Cucumis used here had the potential for paternal mitochondrial inheritance,while the control materials displayed maternal cytoplasmic inheritance. These data provide a foundation for further studies on the molecular mechanisms of mitochondrial paternal inheritance in angiosperms.