Cytological Features,Biochemical Basis And Molecular Marker Of Dominant Genic Male Sterility In Cabbage (Brassica Oleracea Var. Capitata L.)

Male sterility is important in the utilization of hybrid heterosis in cabbage. A dominant genie male sterile (DGMS) source 79-399-3 has been well utilized in commercial cabbage hybrid breeding. However, the mechanism and related molecular base of the male sterility has not been well explored. The present research is to further characterize the pollen morphology, cellular and physiology or biochemical changes during buds development and also markers linked to the gene using cabbage male sterile cabbage as material. The research results are as follows:The cytomorphological observation showed that the anther abortion of dominant male sterility in cabbage occurred during the early pollen mother cell stage, however the peak of abortion took place during the period from pollen mother cell pre-meiosis stage to single nuclear microspore development stage. The abortion has the following characteristics: collapse of organelle structure including nucleus, mitochondrion, endoplasm reticulum, plastid, vacuole; abnormal meiosis of a part of pollen mother cell; early callose deposition; pollen mother cell and microspore surrounded by thick wall and failure of normal development and microspore separation that led to male sterility in cabbage.Abnormal morphological traits were observed on cabbage male sterility pollen grain by both optical and scanning electron microscope. The results indicated that weak or none stained pollen grain, destroyed pollen wall, shirked and cap-like shape of pollen outer wall, the pollen grain clustered and showed a rosette shape were observed.Pollen fertility showed significant difference under the condition of -20 degree for a certain days. From 1 to 210 days, the fertility of pollen grain in sensitive sterile lines is obviously lower than fertile pollen fertility but thefertility of extremely sensitive sterile lines has no difference compared with the fertile ones at most lines. Under the condition of -20 degree, from 1 to 210 days the pollen fertility of different fertile types reduced along with following the prolongation of storage days and showed great difference in pollen fertility reduction.From pollen mother cell stage to dinucleate microspore development stage, the content of IAA, GA and ZR in sterile buds was lower than fertile ones, conversely higher than fertile ones after this stage for IAA, GAa. From tetrad stage to microspore stage, the ABA content in sterile buds was higher than fertile buds. The results indicated that in the early bud development stage the shortage of IAA, GA, ZR and enrichment of ABA is closely related to male sterility in cabbage.The content of 17 free amino acids in sterile buds of mature pollen is higher than the fertile one. The content of glutamic acid in sterile buds is higher than fertile one during bud development. Before single nuclear microspore development stage during the peak of abortion, the content of aspartic acid, alanine, arginine, leucine and lysine in sterile buds is higher than in fertile buds and indicate that the enrichment of these amino acids are closely related to the obortion of male sterility in the early bud development stage in cabbage.RFLP and SSR biotechnology were applied to identify the markers linked to Ms gene based on BSA method. One RFLP markers (pBNll), which show the genetic distance 1.787 to 5.189, and one SSR marker (C03igo) with genetic distance of 4.30 to 8.94 were identified using two backcross cabbage male sterile lines. After testing of different types of cabbage male sterility backcross lines, these two markers can be used for marker assisted selection and the present study mapped the male sterility gene onto chromosome 1 or 8 in cabbage based on RFLP markers.In summary, the dominant male sterility gene was well characterized at morphologic, physiological, biochemical, molecular level and also linked markers. The present research clarified the stage of abortion of male sterile material and its main characteristics, and further found out its abortivemechanism by way of physiology and biochemitry, and t...