| China is the origin centre of Chinese cabbage(Beassica campestris L. ssp. pekinensis (Lour.) Makino), which has been cultivated in China for a long history. The yield of Chinese cabbage is higher than the other vegetables in China. Self-incompatibility and male sterility are important ways of utilization of heterosis in vegetable production. The utilizaion of male sterility simplified the breeding process, improved the purity of seed and then lowered the cost of hybrids. Therefore, the breeding and utilization of male sterile line in the vegetables such as the Chinese cabbages whose nutritive organs are used is one of most important ways of heterosis breeding.A new kind of cytoplasmic male sterile (CMS) line6w-9605A is used in the study. Using the hau CMS line of Brassica juncea as sterile material source, interspecific cross and successive backcrossing with6w-9605B were conducted to transfer the hau sterility cytoplasm to Chinese cabbage, and at eighth backcrossing generation Chinese cabbage6w-9605A with stable sterility was obtained. For the the comprehensive study of the CMS Chinese cabbage, this research focused on the resource evaluation of6w-9605A from phenotype and cytology, cytoplasm fertility, restoring and maintaining relationship and cytoplasmic type. Besides, the transformmation of non-beading Chinese cabbage is studied. At the same time, the BC] of non-heading hau CMS Chinese cabbage line has been obtained. The main results were as follow:1. The morphology and fertility of6w-9605A were observed in2010and2011, which showed that the flower organs of6w-9605A were normal, and in the BC8the anthers were degenerated and completely abortive. The sterility of6w-9605A was stable and completes (100%).2. Anatomical observations of anthers in6w-9605A and its maintainer line6w-9605B in Chinese cabbage were made by means of paraffin sections in order to determine the stage and pattern of anther abortion. The results showed that the anthers of6w-9605B were normal and the abortion of CMS line occurred mainly at the differentiation stage of archesporial cells, which accounted for66.7%of anther abortion and resulted in no pollen sacs. In the remaining33.3%of abortion anthers, pollen sacs were produced but the development of microspores stopped at the late uninucleate or dinucleate stages, and the hypertrophic tapetal cells compressed the microspores and caused the sterility of pollen grains.3. Primers were designed based on the conserved sequences of known CMS-associated genes in the Brassica species, and a product of772bp specific fragment was amplified by PCR with DNA from6w-9605A. Sequence alignment indicated that it was different from orf224and orfl38gene correlated with cytoplasmic male sterility. The sequencing and comparison showed that the specific fragment and hau CMS mustard reached100%in homology, meaning that6w-9605A belonged to CMS type of hau CMS.4. The restorer of6w-9605A was selected through test-crossing of47varieties with AA genome. The result showed that restoring source of6w-9605A was narrow. Only five F1test-crossing combinations had abundant pollen, which might have fertility restore gene for the fertility of6w-9605A.5. The etiolation analysis of the6w-9605A showed that there were no differences between the chlorophyll content of male sterile line and maintenance line with the increasing years of the backcrossing.6. The hau cytoplasm was introgressed to non-heading Chinese cabbage by hybridization and backcrossing in order to utilize the heterosis. The backcrossing of BC1was finished, and the agronomic traits of F1and BC1were also observed, and two combinations which were closed to male parent were selected. |
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