Directional Breeding For The Genetic Male Sterile Line Of Chinese Cabbage And Its Breeding Using MAS

Multiple allele inherited male sterile materials were applied to identify the genotypes of inbred lines using in breeding of male sterile lines in Chinese cabbage. According to the genotype of the target inbred lines, a male sterile strain was used as the source of the male sterile genes, and a directional transfer breeding program was designed to breed new male sterile lines. Several SCAR and SSR markers linked to the male sterile gene Ms and its restorer gene Msf were developed for MAS to solve the problem in identifying genotypes during the transferring of the male sterile line. The effect of the directional transfer breeding was evaluated based on identifying the horticultural characteritics to the newly-bred male-sterile lines and its corresponding hybridized combinations. The main results were as follows.1. The genotypes of the inbred lines a20, A22 and a05 were cheked by using a GMS line (Msms) and a AB line (MsfMs, MsMs) as testcross parents. It indicated that genotypes of all the three inbred lines were msms. According to the genotype, a transfer program was designed with fertile plant of the AB01 line, as the male-sterility source. After the backcross for four generations, a new male-sterile line of folded ecotype "GMS4", which has 100% male-sterile plants and was similar to a20 in most horticultural traits, was bred successfully.2. The results indicated that, when verify the several molecular markers linked to Ms gene, one SCAR marker syau scr01 and one SSR marker syau_m13 were polymorphism between two parents. The accuracy of these two markers in estimating genotypes was 96.7% and 91.7%, respectively. The accuracy could reach 100% when the two markers were used in combination. It indicated that these two markers were applicable in the marker-assisted selection of the genic multiple-allele male sterile line in Chinese cabbage.3. A BC4 mapping populations was constructed with the fertile plant (Msfmsf) which was selfing progenies of the genetic multiple-allele male-sterile AB as the female parent and inbred line'a20'(msms) which is the male parent. Screening 104 SSR primer pairs was performed with near isogenic lines (NILs). The result showed that three SSR markers named syau-m13, syau m14 and BRMS-040 were found to be linked to the target Msf. Based on the genetic linkage analysis, the Msf gene was located on the linkege group R07. Finally, a genetic map of the Msf gene was constructed covering a total interval of 8.6 cM. The three markers were located on the same side of the gene at distances of 6.7,6.7 and 8.6 cM, respectively.4. The GMS lines GMS1, GMS2, GMS4 which come from compound and directional transfer scheme and the fertile target line'a20', AB line'AB01'were used as materials to analysis the effect the two transfer scheme. The result showed that variation coefficient on plant height, angular divergence, leaf length, leaf width, leaf head height, leaf head diameter, leaf headweight of GMS4 was best small and plants was evenness. With the increasing of directional backcrossing generations transfered, variation coefficient and uniformity degree of the genetic male sterile line. We made some hybridized combinations with the newly-bred male-sterile lines (GMS2, GMS4) as the female parents, and with the five elite inbred lines of the corresponding ecotype as the male parents(P1-P5). The results showed that, with the increasing of directional backcrossing generations transferred, variation coefficient and uniformity degree of different hybrid groupsdecreasing, a degressive general combining ability. Depanding on the analyzing results of uniformity degree combining ability disease resistance ability and quality, we select 2 excellent cross combinations of Chinese cabbage (GMS4xP1),L8(GMS4xP3).