Cytological Observation, Gene Location And AFLP Marker Screening Of Male Sterility In Chinese Cabbage

Chromosome localization of genes is an important work for genetic study and breeding practice. In this paper,'Dayang AB line'and a set of trisomics of Chinese cabbage were used as materials. The pollen abortion process of sterile line(A line) was observed by paraffin slice techniques, the location of the gene controlling the male sterility was carried out by primary trisomics analysis, and the molecular markers linked to the male sterile gene was screened by AFLP techniques. The main results were as follows: (1) the paraffin slice observation showed that the primary cytological reasons of male sterility in the sterile line (A line) of chinese cabbage'Dayang AB line'were hypertrophy of the anther tapetum cells, which confined the flowage of nutrition and energe from the tapetum cells to the pollen mother cells, then inducing the microspores could not release from the tetrads normally, finally resulted in the pollen abortion completely at the tetrad formation phase. (2) the bisomic and trisomic analysis indicated that of the all F2 and Tc filial generations of the trisomic hybrids between the sterile line and different trisomics, only the combination of trisomic-4×sterile line, the ratios of male fertile plants to male sterile plants displayed abnormity, i.e 15.5:1 in F2(MsMsms self-cross) population and 3.24:1 in Tc (msms×MsMsms) population, which severely deviated from Mendelian segregation law of 3:1 for self cross and 1:1 for test cross, and other combinations the ratios varied from 2.60:1 to 3.76:1 and 0.81:1 to 1.48:1 respetively, which all fit Mendelian segregation law for monogenic factor. This suggested that the heredity of male sterility was only associated with the trisomic-4, i.e. the gene controlling male sterility located in the chromosome 4 of Chinese cabbage. (3) Further trisomic analysis based on chromosome segregation and on chromatide segregation indicated that the gene in the chromosome 4 was close to the centromere. (4) with 124 primer pairs, a specific amplified DNA fragment with 398bp(a AFLP marker naming E34M49) was preliminary obtained, and the genetic distance between the marker and the gene was about 1.2cM by analysis of MAPMAKER/EXPVersion 3.0.