Screening Of Resistant Germplasm To Clubroot In Brassicaceae

Clubroot is a soil-borne disease caused by the infection of clubroot bacterium(Plasrnodiophora brassioae Woron).Clubroot disease parasitizes at the roots of cruciferous crops,affects the plant's absorption of water and nutrients,and eventually results in a decline in crop yield and quality.Rapeseed is an important oil crop in China,but the development of agricultural mechanization spreads clubroot disease rapidly in our country.The main rapeseed production areas including Hubei,Anhui,Sichuan,and Yunnan are facing serious harm from clubroot disease.Breeding rapeseed varieties resistant to clubroot is the most economical and effective method for controlling clubroot disease.Phytophthora is a diverse and fast-changing race,while the current resistance of rapeseed varieties to clubroot is controlled by a single gene,and suffers from severe challenge of resistance loss.Phthalocyanine ECD04 is excellent in resistance and contains multiple loci of resistant genes.The loci Pb Ba8.1 has immune characteristics to physiological races in different regions.Then,the following results are obtained:1.By using the BC₁F₂ population constructed in our laboratory from the cross between ECD04 and Huashuang 5 to identify the physiological races in the Jixi area,153 disease-resistant strains were screened out.During the identification with closely linked molecular markers of Pb Ba8.1 and CRa,83 new disease-resistant strains were found to contain no Pb Ba8.1 and CRa genes,laying a foundation for future gene mapping and multi-site polymerization breeding.2.In order to verify the accuracy of CRa gene detection,the ECD04 sequencing results were used in this study.According to the gene differences between ECD04 and Huashuang5 on chromosome A03,we design one marker of CRa gene and marker M1 was screened to be closely linked to the CRa gene and be well polymorphic.3.In the related species of Brassica napus,Combination of identification results and uses tightly linked molecular markers with Pb Ba8.1 and CRa,and using CAPS markers developed based on the Pb Ba8.1 gene,the anti-disease turnip'17ZY1383','17ZY1390'in the industrial system and the disease-resistant Chinese cabbage'CRcb'collected in our laboratory were found not to contain the Pb Ba8.1 gene.The anti-disease mustard'17ZY0012'in the industrial system was also free of Pb Ba8.1 and CRa genes.