Diagnose And Control Technology Of Plasmodiophora Brassicae

Clubroot caused huge economic losses worldwide every year. The number of dormant spores of Plasmodiophora brassicae in soil rapid increase by continuous cropping. The difficulty to control clubroot are gradually increased. Therefore, the establishment of a viable comprehensive strategy for bacteria detection and prevention of Plasmodiophora brassicae are significant.The results are as follows:1. A quick and reliable method can be used to inoculate Chinese cabbage for Plasmodiophora brassicae. Different ways were used to compare inoculated extent of Plasmodiophora brassicae by seedling methods,pH environment of culture system,inoculation methods and inoculation concentration. The results showed that the inoculation method of transplanted plants were seeded in an acidic environment, inoculate with high concentrations of Plasmodiophora brassicae were mixed and sealing are the best one.2. The nested PCR assay could be used to rapidly detect Plasmodiophora brassicae in soil.Two primer pairs were designed specifically to amplify DNA from Plasmodiophora brassicae by nested-PCR.PCR detection indicated that GZ10/GZ11,GZ12 /GZ13 and nested-PCR could amolify 574bp,277bp and 277bp fragment only from P.brassicae,respectively,no amplification product was observed from healthy plants.In conventional PCR ,the sensitivity of detection was of 217 ng·L-1 and 2.17μg·L-1 P. brassicae for both primes,in the nested-PCR the detection limit was 217 pg·L-1. The sensitivity of detection of infected soil DSI was 11.67.3. Gained a real-time PCR detection system more sensitive than the nested-PCR. Designed a specific primer pairs(GZ12 / GZ13)suitable for fluorescent quantitative PCR, constructed a expression vector, expressed by E. coli expression system,the transformed plasmid of Plasmodiophora brassicae was formed. Gradient dilution method by plasmid was used to established fluorescence quantitative standard curve, and testing for the threshold test and field samples. Dilution of the inoculation of the threshold soils were detected by fluorescence quantitative PCR technology.All samples could be quantitatively assessed.The concentration of 0.0002g root/ g soil samples with the non-performance symptoms in inoculation test. The quantitative fluorescence quantitative PCR could still detect the bacterial content of the soil samples was 5.66×104 dormant spores / g soil. Fluorescence quantitative PCR technique were detected for samplinges of 16 fields, in addition to soil 13 ,soil 16 with non-performance symptoms and negative control,all bacterial content of the soil were quantitative.And quantitative test results in accordance with soil samples symptoms descripted. 4. Screening for resistance varieties of Chinese cabbage for Plasmodiophora brassicae in vivo,obtained two high-resistant Chinese cabbage varieties. They are:Ness and Kim,Jin-high No. 2.5. Screened one pharmaceutical drugs of high controling efficacy for Plasmodiophora brassicae.The control efficacy of 50% fluazinam SC(1g/m3)mixed was better than the control efficacy of other fungicides significantly.Mixed drug and drench was used to evaluated the control efficacy of 10 kinds of fungicides on clubroot of Chinese cabbage by pot experiments.Three pharmaceutical drugs selected by potted experiment was carried in field experiment. The results show that The control efficacy of 50% fluazinam SC(1g/m3)were above 80% by Pot experiment and field experiment,which was better than the control efficacy of other fungicides significantly.This is the first report for the detection of P. brassicae in the soil by quantitative PCR technique,and maked statistical analysis for test results associated with the disease index.This is contribute to the rapid disease prediction and early prevention.Put the detection technology,high resistant cultivars combined with efficient pharmaceutical.This is improved safety production of Chinese cabbage in China and market competitiveness international, and promote the safety implemention of control strategy to clubroot disease of Chinese cabbage, and increased security forces of income of farmers and contributed to the agricultural production.