Breeding Of The Recessive Genic Male Sterility Line With The Same Genetic Background As Its Temporary Maintainer TAM By Marker-assisted Selection

Heterosis utilization is an efficient way to improve yields,quality and resistance (tolerance) of crops,and has been applied widely in the world recently.And highlyefficient pollination control system is the key for hybrid seed production.Male sterility is an important pollination control system in rapeseed,and the recessive genic male sterility (RGMS) has great potential in hybrid breeding,because of it's a series of advantages, such as complete and stable male sterility,sufficient restore lines and so on.However,the production of F₁ hybrid seed requires the removal of 50%of the fertile plants in the male sterile line which limits its wider application.In 1993,Chen et al.reported a RGMS line with an epistatic inhibitor gene,which made a three-lines system available in hybrid seed production and lay the foundation for its widely utilization.A bottleneck of this model in the traditional breeding program is that breeding of the temporary maintainer(TAM) and its RGCMS Line with the same genetic background.The aim of this study is to breeding a male sterile line with the same genetic background as the available maintainer line TAM, by molecular marker-assisted selection,and to further promote the application of this RGCMS in Brassica napus L.The main results are as follows:1.Male fertile plants(9012B(Ms₃ms₃ms₄ms₄RfRf) in 9012AB were crossed with TAM (ms₃ms₃ms₄ms₄rfrf),and a total of 162 individuals of F₁ were obtained,which included 82 fertile plants(Ms₃ms₃ms₄ms₄Rfrf) and 80 sterile plants(ms₃ms₃ms₄ms₄ Rfrf).The segregation ratio of fertility:sterility agreed with expected 1:1.Then the crosses were made between sterile plants and fertile plants,and a F₂ population with 390 plants were obtained;2.Two Ms₃ linked SCAR markers MT8 and 9W23,and one Rf linked SSR marker Ra2G08 were used for prospect selection in the F₂ population.The segregation ratio of Ms₃ ms₃:ms₃ ms₃ in 390 plants was 200:190,RfRf Rfrf:rfrf was 105:196:89,and both of them were in accordiance with the expectations.The number of Ms₃ms₃ms₄ms₄Rfrf individuals was 92 in the F₂ population and in accordance with the expected 1:4.Five plants were selected out after background selection with AFLP markers,and F₂BC₁ were obtained by the backcross with TAM as the female parent. 3.33 F₂BC₁ individuals were grown in Gansu,and two plants(Ms₃ms₃ms₄ms₄Rfrf) of them which were the most similar genetic background with TAM were selected by prospects and background selection and then were backcrossed with TAM for getting BC₂F₁,and the BC₁F₂ generation was then obtained by selfing.4.The BC₂F₁ and BC₁F₂ were planted at Wuhan in fall of 2008.By the same prospects and background selection for 80 individuals of BC₂F₁,12 plants with the genotype of Ms₃ms₃ms₄ms₄Rfrf were identified.This result agreed with the expected 3:1.The 12 plants were found to be very similar with TAM in the genetic background by the background selection.So all plants were selfed for producing BC₂F₂.At the same time, the background of BC₁F₂ was proved to be very different with TAM,so it can not be further used for the selection of the male sterile line.5.The BC₂F₂ has been grown in Gansu Province in the summer of 2009.And with assistance of the marker selection,a RGCMS line with the same genetic background as its temporary maintainer TAM will be obtained...