Development Of Molecular Markers Linked To The Recessive Geneic Male Sterility Gene Ms₄ In Brassica Napus L

9012AB is a recessive epistatic genic male sterility (GMS) two-type line in which the sterility is controlled by two pairs of recessive duplicate sterile genes (ms₃ms₃, ms₄ms₄) interacting with one pair of a recessive epistatic inhibitor gene(Chen et al. 1998). This model provided a theoretical basis not only for the three-lines commercial hybrid seed production but also for the wide range application of the recessive genic male-sterility. At present, much great progress has been made in both breeding and genetic research. On the base of previous reseach achivements, the aim of this study is to indentify molecular markers linked to Ms4, and provide information for marker assisted selection and ms₄ gene's clone. The main results of the present study are as follows:1 In order to indentify molecular markers linked to Ms4, two BC1F1 populations from WLA×WLB and GOSB×9012A were constructed. There were 59 and 60 fertile plants, as well as 58 and 63 sterile plants in the two populations, respectively, and the ratio of fertility: sterility of both populations agreed with expected 1:1.2 By the BC1F1 population from 'WLA x WLB', DNA bands amplified from 2560 pairs of AFLP primer combinations were screened. As a result, 6 AFLP markers named as BH1, BH2.......BH6 respectively were found linked with the Ms4 locus.3 At the same time, by the other BC1F1 population from GOSB×9012A, 1024 primer combinations were screened, and 16 markers named as BP1----BP16 respectively were idendified linked with the Ms4 locus.4 The software 'MAPMAKER/EXP 3.0' was employed to detect the linkage relationship between MS4 gene and the markers mentioned above. As a result, 16 markers were proved linked with the Ms4 locus, which were located at both sides of the MS4 locus and the the distance between closest maker and the Ms4 locus was 2.2cM.5 22 AFLP markers were sequenced and blasted against the Arabidopsis genome using the programme BLASTn. As a result, 7 markers were found homologous with Arabidopsis genome and BH6 had the highest homologous (85%).