Study On The Pathogen Indentification And Resistance Indentification Method Of Sclerotinia Rot In Chinese Cabbage

Chinese cabbage Sclerotinia rot is growing increasingly as one of the main diseases in China, Therefore, an urgent problem is to setup a convenient, rapid and exact method for identify the resistance of Chinese cabbage(Brassica campestris L. ssp penkinsis) germplasm resources to Sclerotinia rot, which will promote the step of germplasm and new varity breeding. In this research, the biological characteristics of Sclerotinia rot pathogen, the method of artifical resistance identification in chinese cabbage have been done based on the Sclerotinia rot pathogen isolation and identification. The major results were as follows:1. The pathogen of Chinese cabbage Sclerotinia rot was identified as same as sclerotinia rot of colza through pathogenicity test, morphology observation and analysis of nucleotide sequence of internal transcribed spacer(ITS).2. PDA medium is more suitable for Sclerotinia sclerotiorum culturing than Czapek-Dox Agar. In which, the optimum concentration of potato is 200 g/L, the optimum concentration of glucose is 30 g/L, the optimum pH is 4 and the optimum temperature is 25℃. The optimal temperature for sclerotia germinating induction was between 4℃ to 10℃ and the sclerotia germination is best when treated for between 3 weeks to 5weeks under 4℃. The suitable culturing temperature for sclerotia germination was between 15 ℃ to 25 ℃ after low temperature treated. Apothecium is pale yellow, constituting ascus handle and fruitbody. Each ascus contains 8 ascospores, linearly arranged. Ascospores are colorless with two nuclei.3. An optimal artificial inoculation identification method for Sclerotinia rot of Chinese cabbage at seedling stage was preliminarily established. The key procedures of inoculation is spraying ascospores liquor of 1×106 ascospores /mL on the seedlings of 4~5 true leaves stage and then kept at 22℃ for 12 days.4. By comparing the results of inoculation identification methods on cotyledon seedling, detached cotyledons, true leaves seedling and detached leaves. It was found that the best artificial inoculation identification method is spraying ascospores liquor of 1×106 ascospores /mL on detached leaves and then kept at 22℃.