Development of diagnostic probes allowing the identification of male-sterile and male-fertile cytoplasms in beets

目前所有甜菜品种都是基于唯一一种类型(欧文型)的雄性不育细胞质。这种细胞质的一致性使作物容易受到细胞质特有的疾病的影响，因此扩大细胞质的变异是可取的。本研究的目的是筛选甜菜和野甜菜种质资源线粒体DNA的差异，利用这些诊断探针鉴定新的雄性不育细胞质。我们从甜菜线粒体DNA克隆文库中制备了31个探针。利用这些探针对供试材料的总DNA进行了Southern杂交分析。结果表明，大多数野生甜菜材料都有新的线粒体基因组类型，只有少数与已知的基因组完全相同，如Owen类型和正常可育基因组。新的线粒体基因组类型可以分为两类，第一类与已知基因组相似，第二类代表基因组的镶嵌结构。我们还发现，拥有新线粒体基因组的几个野生甜菜表现出花粉不育。因此，确定这里检测到的新的线粒体基因组类型是否与细胞质雄性不育相关是有意义的。

All current sugarbeet cultivars are based on the only one type (the Owen type) of male-sterile cytoplasm. This cytoplasmic uniformity renders the crop vulnerable to cytoplasm-specific diseases, and a broadening of the cytoplasrnic variation is desirable. The objective of this study was to screen Beta vulgaris and B.maritima germplasm accessions for differences in their mtDNAs, using the diagnostic probes to identify new male-sterile cytoplasm's.We developed 31 probes prepared from a mitochondrial DNA clone bank of sugarbeet. These probes were sequentially used for Southern blot analysis of total DNA from the germplasm accessions. The results indicated that most of the wild beet accessions have novel types of rnitochondrial genomes and that only few are completely identical to previously known genomes such as the Owen type and normal fertile genomes. The novel mitochondrial genome type can be classified into two categories, the first one being similar to known genomes, and the second representing a mosaic organization of genome. We also found that several wild beets possessing the novel mitochondrial genomes show pollen sterility. It is thus of interest to determine whether or not the novel mitochondrial genome types detected here are correlated with cytoplasmc male sterility.