Transfer And Evaluation Of Clubroot Resistance Genes Of Chinese Cabbage

Chinese cabbage?Brassica rapa L.ssp.Pekinensis?is a plant of crucifere,Brassica,and is grown widely in China.Cruciferous clubroot is a disease caused by soil-borne Plasmodiophora brassicae Woron,it infect the roots of plants.In recent years,with the area of land polluted by clubroot in cabbage growing area is increasing,it has adversely affected the yield and quality of Chinese cabbage.The purpose of this study is to use the MAS technology to aggregate clubroot resistance sites CRd and CRa into cabbage materials and obtain new cabbage materials with excellent agronomic properties through backcross breeding.The main findings are as follows:This experiment used cabbage variety 'CR252' as the recurrent parent and cabbage variety 'CR84-74' as the donor parent.The F₁ generation was obtained by crossing 'CR252'and 'CR85-74'.On this basis,after backcross and self pollination,we used the linkage markers with CRd and CRa genes,and the full-length markers of the two genes to carry out foreground selection,and 95 SSR markers screened in the early stage to carry out background selection,combining with the results of disease resistance identification,and obtain CRd and CRa disease resistance aggregated plants with a background recovery of100%.In this test,it started to screen the plant background marker in 'CR5274' BC₃F₁ generation.The phenotype of the parents and F₁ generations were verified by P.brassicae of Xinmin?LNXM-1,Pb6?,and the resistance of each backcross generation was identified.The results manifest that 'CR85-74' is immune to P.brassicae of Xinmin,‘CR252' is highly susceptible to P.brassicae of Xinmin,F₁ is resistant,and the ratio of resistant and susceptible in each backcross generation is close to 1:1.Field identification indicate that the ratio of resistant and susceptible in'CR5274' BC₃F2 generation is 3:1,and the ratio of resistant and susceptible in 'CR5274' BC₄F₁ generation is close to 1:1.Theresults manifest that the transgenic progeny could resist P.brassicae of Xinmin.At the same time,the identification of BC₃F₁ and BC₄F₁ show that the polymeric material could resist many physiological races.The agronomic characters of 'CR5274' BC₃F2,BC₄F₁ and BC₄F2 plants are investigated,the results show that there is no significant difference in growing period,pod characters and main botanical characters between the 'CR5274' and the 'CR252'.