Pathogenicity Differentiation Of Sclerotinia Sclerotiorum And Biochemical Mechanism Of Rape Resistance To Scleroitnia Stem Rot

Rape Sclerotinia stem rot is a worldwide disease of oilseed rape. The disease occurs in China as well, ranking in the first of the rape’s three major diseases. Particularly, the Yangtze River and southeastern coastal areas are the most common and serious. And it seriously impacts the yield and quality of rapeseed. In this paper, The pathogenicity of24isolates of Sclerotiinia sclerotiorum which obtained from Tongcheng, Wangjiang, Ningguo, Jingde, Nanling and Shouxian in Anhui was investigated by applying inocluation isolated leaves inoculation. And make study on biological characteristics of S. sclerotiorum of different pathogenicity The results showed that all of the tested isolates caused stem rot on rape. Different rapeseed (Brassica napus L) varieties，such as Deyou5，Zhongyou821,Wanyou14and Zayou1，with different resistance to sclerotium blight(Sclerotinia sclerotiorum) were selected as materials. After S．sclerotiorum was inoculated on rapeseed at full bloom stage,the complete functional leaf were chosen to analyze the physiological and biochemical characters.The results indicated that change of the content or activity of the physiological and biochemical characters after inoculation is correlated with S．sclerotiniose resistance to some degree．1. Pathogenicity differentiation of Sclerotinia sclerotiorum isolates from different areas and comparison of biological characteristicsThe pathogenicity of24isolates of Sclerotiinia sclerotiorum which obtained from Tongcheng, Wangjiang, Ningguo, Jingde,Nanling and Shouxian in Anhui was investigated by applying inocluation isolated leaves inoculation. And make study on biological characteristics of S. sclerotiorum of different pathogenicity The results showed that all of the tested isolates caused stem rot on rape, and there was a significant difference in the average length of the lesions caused by different isolates, suggesting that there was significant differentiation in pathogenicity of S. sclerotiorum strains to rapeseed among isolates. The pathogenicity of the isolates was related to their localities to some degree.Hyphae can grow from5℃to30℃and the optimum temperature was from20℃to25℃. Pathogenic fungus can grow under condition of pH2.0～12.0, The optimum Ph for mycelium growth were5.0～7.0, respectively. It was benefitial for mycelial growth under the condition of alternating between illumination and darkness. The strains with high pathogenicity can grow better under all menstruated temperatures and pH.2. Dynamics of polyphenol xidase activity in rapeseed plants after being inoculated with S．sclerotiorumPhenols substance is changed into quinones substance after touch PPO.The quinones substance polymerize into brown material， lead the organization browning reaction.Apply the methord of spectrophotometer to measure the product.The results showed that all the physiological and biochemical characters of all selected varieties changed after the inoculation．The increase of PPO activity in less-resistant varieties was higher than that of resistant varieties．The results also indicated that change of the content or activity of the physiological and biochemical characters after inoculation iS correlated with S．sclerotiniose resistance to some degree．3. Dynamics of superoxide dismutase activity in rapeseed plants after being inoculated with S．sclerotiorumIn the condition of oxides and light,the lactochrome could be deoxidized,and product oxonium ion.The oxonium ion will deoxidize NBT into the blue material. The latter has the most absorbing value in560nm wavelength.And SOD can curb this response. Therefore, we can use the reductions to measure the enzyme activity. The results showed that all the physiological and biochemical characters of all selected varieties changed after the inoculation．The increase of SOD activity in the resistant varieties such as Deyou5and Zhongyou821was higher than that of the less-resistant varieties such as Wanyou14and Zayou1．The results also indicated that change of the content or activity of the physiological and biochemical characters after inoculation iS correlated with S．sclerotiniose resistance to some degree．4. Dynamics of peroxidase activity in rapeseed plants after being inoculated with S．sclerotiorumIn the condition of hydrogen peroxide,POD can oxidize the guaiacol into dark brown material.Apply the method of spectrophotometer to measure the OD value in470nm wavelength and calculate the the enzyme activity.The results showed that all the physiological and biochemical characters of all selected varieties changed after the inoculation．The increase of POD activity in the resistant varieties such as Deyou5and Zhongyou821was higher than that of the less-resistant varieties such as Wanyou14and Zayou1．The results also indicated that change of the content or activity of the physiological and biochemical characters after inoculation is correlated with S．sclerotiniose resistance to some degree．5. Difference of oxalic acid content in rape plants after inoculation with Sclerotinia sclerotiorumThe theory of titration of potassium permanganate:Between the oxalic acid and the potassium permanganate,there is oxidation reaction.Use the potassium permanganate titrate oxalic acid,according to the colour of product to determinate the endpoint,in accordance with the reaction of the formula and the volume ofpotassium ermanganate to calculate the content of oxalic acid.The results showed that all the physiological and biochemical characters of all selected varieties changed after the inoculation．the content of oxalic acid in less-resistant varieties was higher than that resistant varieties．The results also indicated that change of the content or activity of the physiological and biochemical characters after inoculation is correlated with S．sclerotiniose resistance to some degree．...