| The present study is aimed to solve the problems in the transfer and utilization of the GMS lines in Chinese cabbage with 100%male-sterile plants.As the first step,with the male-sterile plant of an AB line as the testcross line,we identified the genotypes on the multiple-allele male-sterile locus of the fertile lines of three basic ecotypes(cylinder, level-head,and ovate ecotypes),respectively,under the guide of the "genetic hypothesis of the genic multiple allele male sterile gene in Chinese cabbage".Secondly,the male-sterility source material was selected,according to the genotype of the target lines.Thirdly,a new directional transfer program was designed and carried out to transfer relevant GMS genes to the fertile lines of three basic ecotypes and breed new male-sterile lines.Finally,effect of the directional transfer was evaluated,on the basis of the comparative analysis on the horticultural traits of the newly-bred male-sterile lines and the corresponding hybridized combinations.The main results were described as follows:1.The testeross results indicated that three genotypes(Ms~fMs~f,Ms~fms,and msms) were found on the target locus in all the 68 fertile lines of the three basic ecotypes,and the frequency of these three genotypes were 29.41%,26.47%,and 44.12%,respectively.The gene frequency of Ms~f was 42.65%,and that of the ms was 57.35%.The msms was predominant in the fertile plants of cylinder and level-head ecotypes,while the Ms~fMs~f was more frequent in those of the ovate ecotype.2.We identified the genotype of three target lines(03S001 of the cylinder ecotype,03S012 of the ovate ecotype,and 03S050 of the level-head ecotype),with a GMS line 3A(Msms) and the male-sterile plant(MsMs) of an AB line AB01 as the testcross parents.It indicated that the 03S001 was identified as Ms~fMs~f,while the 03S012 and 03S050 were identified as msms.3.According to the genotype(Ms~fMs~f) of 03S001,a transfer program was designed with 3A, a GMS line in Chinese cabbage,as the male-sterility source.After the backcross for four generations,a new male-sterile line of cylinder ecotype "GMS002",which has 100% male-sterile plants and was similar to 03S001 in most horticultural traits,was bred successfully. 4.According to the genotype(msms) of 03S012,a transfer program was designed with the fertile plant(Ms~fMs) of an AB line as the male-sterility source.After the backcross for six generations,a new male-sterile line of ovate ecotype "GMS003",which has 100% male-sterile plants and was similar to 03S012 in most horticultural traits,was bred successfully.5.According to the genotype(msms) of a fertile line of level-head ecotype,03S050,a transfer program was designed with the fertile plant(Ms~fMs) of an AB line as.the male-sterility source.After the backcross for six generations,a new male-sterile line of level-head ecotype "GMS004",which has 100%male-sterile plants and was similar to 03S050 in most horticultural traits,was bred successfully.6.Through the tests on the horticultural traits and evenness of the newly-bred male-sterile lines(GMS002,GMS003,and GMS004),it was validated that the "directional transfer program" could realize the simultaneous transfer of both the male sterility and the other traits.Further,it also indicated that the backcross should be made for at least four generations between those in the same ecotype,while six backcross generations are necessary for the transfer over ecotypes.7.We made some hybridized combinations with the newly-bred male-sterile lines(GMS002, GMS003,and GMS004) as the female parents,and with the elite inbred lines of the corresponding eeotype as the male parents.The results showed that the newly-bred male-sterile lines were characterized by high combining ability,stable male sterility,and significant heterosis.Three elite hybridized combinations(C3 of the cylinder ecotype,Y1 of the ovate ecotype,and P3 of the level-head ecotype) were successfully selected and bred based on the combining ability analysis.
|
PDF Full Text Request