Resistance Identification And Molecular Marker Screening Of Clubroot In Brassica Oleracea L

The cabbage is widely cultivated around the world. Cabbage is an important cruciferous vegetable crop in China, playing an important role in the annual supply of vegetables. Clubroot disease is caused by a soil-borne obligate biotroph, Plasmodiophora brassicae, and is one of the most devastating diseases in Brassica crops worldwide. Plasmodiophora brassicae, the causal agent, shows a wide variation for pathogenicity. Severely infected roots cannot take up sufficient amounts of nutrients and water, causing a reduction in yield of Brassica vegetable. The disease limits the spread of Brassica crops into those areas where soil and climatic conditions support infection. It is controlled most effectively by the use of resistant cultivars. Marker-assisted selection is now available for clubroot resistance.In the paper, we identified the main pathotypes of Plasmodiophora brassicae from different disease areas suffered from cabbage crops clubroot by inoculating resting spore suspension in controlled environment. In order to screen genetically superior cabbage new plant variety and elite parental lines, resistance screening tests of clubroot were done according to the field and greenhouse testing experiments on the base of known physiological race. In this research, we perform a comparative study of CR genes identified in previous reports to picking out molecular markers linkaged to CR genes in cabbage. The main results are as follows:(1) The result showed that physiological race4of Plasmodiophora brassicae, as classified on the differentials of Williams, was detected in infested roots from Fuling in Chongqing. And physiological race7and11were detected, respectively in the roots from Songming in Kunming, Yanbian in Panzhihua and Xindu in Chengdu. (2) In this study, the resistances of79cabbage hybrids to clubropt were identified by field inoculation method. The results showed that8,20, and20hybrids were high resistant, resistant, and tolerant to clubroot, respectively.(3) Test for clubroot resistance in controlled environment indicated that: a, Cabbage new hybrids GZ04, GZ09, GZ40, GZ76, and GZ80were tolerant to clubroot. GZ03, GZ19and GZ78were resistant to clubroot. GZ78had the highest resistance to clubroot. b, Balkan was the best one among all14elite parental lines, which had the highest resistance. There are6resistant materials,4tolerant materials. The remaining three foundation parents were susceptible materials.(4) This study improved the polyacrylamide gel electrophoresis. Fixation is not essential in the polyacrylamide gel electrophoresis. The efficiency of500ml recycled staining solution added0.2g of solid silver nitrate was same as the new solution.(5) We screened28molecular markers in total, but we did not find any available marker. The same clubroot resistance gene-specific molecular markers had collinearity between B. rapa and B. oleracea. The sequence analysis showed that Brassica napobrassica (Rutabaga) Laurentian and Wilhelmsburger had homology with Crrla in a region, and GZ87had homology in another region.