Abstract: 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 resultrevealed 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.

Key words: Cucumis, paternal inheritance, mitochondrial, MTG-DAPI double-stain