Construction Of Canola(Brassica Napus)Introgression Line Libraries Containing A~r And C~c Subgenome Components

A third generation of new-type Brassica napus(B. napus) with hundred of inbred lines were developed by means of a massive interspecific hybridization, marker-assisted selection and generation of different selfing in our group. A large amount of subgenomic fragment from Ar genome of B. rapa and Cc genome of B. carinata were integrated into those lines. As a result, abundant phenotypic variatione and strong heterosis was observed in the inbred lines and their derived hybrids crossed with traditional B. napus, respectively. Here, we aimed to develop a spring-type and a winter type introgression line population of B. napus with different segments of new-type B. napus by the crossing between traditional cultivars of B. napus and new-type B. napus, followed with multiple rounds of backcrosses to traditional B. napus assisted with molecular marker selection, which would provide us introgression populations for futher dissecting the impacts of different exogenous introgression on B. napus.In order to successfully create introgression line population within three years, laboratory experiments, field hybridization and selection were conducted simulta neously. Tactic of summer breeding was also used to construct spring type and winter type introgression population. As follows:In year one(2013.7-2013.12), we obtained the F1 hybrids between new type B. napus and spring type B. napus and appraised the heterosis. Furthermore, 5 pairs SSR primers were used to identify the true hybrids. As a result, 46 true hybrids were identified from 48 F1 hybrids.In year two, the BC1F1 and BC2F1 population were constructed, and 260 true hybrids were identified with 6 pairs SSR primers. In order to effectively select elite combinations, 3000 SNP markers were used to analysis the content of extraneous A~r/C~c as well as the genetic distance between the new-type B. napus and recurrent parents. Two new-type B. napus lines(13R066 and 13R113) were selected for spring type B. napus introgression population after the yield trial.In year three, we confirmed that the genome-wide introgression of new type B. napus in BC2F1 by genotyping.In year four, we constructed the BC4F1 population and BC3F2 population with ordinary spring type B. napus as recurrent parent.Finally, two spring type B. napus introgression populations(13R066-BC4F1 and 13R113-BC3F2) were constructed after initial hybridization, four-round backcrosses and one year selfing.The construction of winter type B. napus introgression was conducted at the same time. However, because the strict vernalization requirement of long period of time with low temperature, only three round backcrosses were carried out. Two winter type B. napus introgression populations were constructed(13R143-BC3F1 and 13R172-BC2F2).By hybridizing ordinary spring type and winter type B. napus with new type B. napus who has elite agronomic traits and large amount of extraneous subgenomic fragments, then backcrossing with ordinary B.napus as recurrent parent, we have created spring type and winter type introgression population containing Ar and Cc fragments. These materials would be of great help for further understanding and dissecting the impact of extraneous subgenomic fragments introgression.