Molecular Genetic Diversity In EMS Mutant Progenies In Brassica Napus L.

Rapeseed is an important oil crop in China. Brassica napus L. is one of the main cultivars of rapeseed. B. napus has a relatively narrow genetic background as compared to other Brassica species, so it’s available resources are limited. Mutation is a very useful method to create genetic variation in available rapeseed germplasm resources. The seeds of Zhongshuang No.9 variety were treated by 1.0% concentration of Ethyl methyl sulfonate(EMS) to create a mutant library, which including flower, leaf, silique, seed and plant type mutant. One hundred and thirty-eight M3 mutant lines from this mutant library(Zhongshuang No.9 included as control) were selected, phenotyped and genotyped by using SSR and SRAP molecular markers. The main results are as following:(1)The morphological variation of M3 lines was abundant. Mutations in flowers were observed, which included male sterility, no gynoecium, wrinkled, large, multiple, small,elongated, revolute petals and round inflorescence, and white flowers and two flowers borne on one stalk. leaf mutations included involute, light green, and blackish green leaf. Mutation in silique included convex shape, purple colour, dense, gracile silique, dumpy and erect siliques. Seed mutation contained yellow, brown and large seeds. Mutation in plant type included compact, composite branches and purple plant.(2) Twenty-four clear and high polymorphism SRAP primer combinations were selected from 646 SRAP primer combinations. A total of 360 amplified fragments including102 polymorphic fragments were detected by 24 SRAP primer combinations, with an average 28.33% of polymorphic fragment percentage. 24 SRAP primer combinations can detect polymorphic fragment from one to ten; The primer combination Em11+Me21 just amplifies 1 polymorphic fragment, but Em15+Me11 can amplify 10 polymorphic fragment.The polymorphism information content(PIC) value is from 0.17(Em14+Me23) to0.85(Em15+Me11), with an average of 0.60.(3) Twenty clear and high polymorphism primer pairs were selected from 380 primer pairs. One hundred and ninety-six amplified fragments containing 91 polymorphic fragments were detected by 20 SSR primer pairs,with an average 46.43% of polymorphicfragment percentage. Primer pair CB10028 amplifies 8 polymorphic fragments, but Ni4-C06 and Na14-D07 just amplify two polymorphic fragments. Every primer pairs can detect polymorphic fragments from two to eight. The PIC value ranged from 0.21(Ni4-D09)to 0.80(CB10028), with an average 0.59.(4) The primer polymorphism analysis, cluster analysis, principle component analysis and population genetic structure analysis showed that EMS-induced mutations in Zhongshuang No.9 can be detected at the molecular level and there are extensive genetic differences among the mutant progenies. Further studies could focus on the mutants which have small genetic similarity coefficient from the mutant basic material to explore their practical value and provide new germplasm resources for rapeseed breeding.