Genotype Identification And Flower Morphologic Structure And Development Comparative Study Of Brassica Oleracea L. CMS

Utilization of male sterile lines has became another important approach in cabbage (Brassica oleracea L.) hybrids breeding instead of self-incompatibility lines.At present,a lot of breeding groups have introduced a lot of cytoplasmic male sterile sources through different ways to breed new sterile lines and hybrids. However, due to less understanding about the background of the introduced sterile sources, it is hard to bring out an useful method to overcome abnormal development of the flower organs and unstable fertility after backcrossing. Therefore, it is necessary to clarify the genetic background of cytoplasmic male sterile sources and the morphological characteristics and fertility stability in different nucleus backgrounds in cabbage, which will have important value for cabbage hybrid breeding by using cytoplasmic male sterile lines in the future.There for, cytoplasmic genotype, floral organs morphology and anther development cytology were investigated in this study. The aim is to find new and good sources of cytoplasmic male sterility in cabbage,which will be useful for further male sterility research and practical breeding in cabbage.The CMS lines with same nucleus genetic background or CMS lines with differen nucleus genetic background were used to analyze in this research. First,a genotype identification of CMS lines were performed.Then the morphology and cytological features of anther abortin of floral organ were investigated. The results are as follows:1. Based on the results of genotype identification of70cytoplasmic male sterile materials of Brassica oleracea,13of them belong to Nap CMS,55lines belong to Ogu CMS,2lines showed both Nap cytoplasm and Ogu cytoplasm genetic background. Moreover,we found that15Nap CMS lines contain an open reading frame "orf228" with687nucleotides and code228amino acids.2. According to the results of floral organs morphology investigation, Ogu CMS lines can be divided into two groups. The first group Ogu CMS lines including materials(87,100-104), which were breeded by the cytoplasmic male sterility source introduced from Tianjing in2000, showed carpel or filamentous stamens, curved pistils and smaller nectaries. The second group of Ogu CMS lines including materials(105-117), which were breeded by the cytoplasmic male sterility source introduced from Beijing in2003, showed normal opening flowers, completely degenerative stamens, normal development pistils and larger nectaries. However, part-open or close flowers, curved pistils, medium volume, shield or petal-shaped anthers were observed in Nap CMS lines.3. Cytological observation showed that anther abortion occurred on sporogenous cells to pollen mother cells stage in the first group of Ogu CMS lines, the anther abortion is due to delayed pollen sacs differentiation or rarely differentiation, and differentiate deformity pollen sacs.Anther abortion of the second group of Ogu CMS lines occurred on the tetrad stage to uninucleate stage. Follow more tapetum cells proliferateion, microspores were squeezed to the center of the anther chamber and degradate with the tapetum cells together. In the Nap CMS lines, the anther abortion occurred on the uninucleate microspores stage, the uninucleate microspores develop into a shell-shape, or part of them can develop into mature pollen but dehiscence anthers result in incapable pollen shed. And the abnormal number of pollen sacs are observed in Nap CMS lines.