| The wheat sharp eyespot, caused by Rhizoctonia cerealis Vander Hoeven, is one of the major wheat diseases in our country. With the change of cultivation system, fertilizer and water conditions, the wheat sharp eyespot in China's major wheat producing areas is especially common and serious harm, seriously affect the wheat high and stable yield. In this paper, preliminary analysis the pathogenic mechanism of cell wall degrading enzymes produced by Rhizoctonia cerealis, so as to further research for disease prevention and the molecular mechanisms of pathogen.1 In this paper, 10 strains were screened from 114 Rhizoctonia cerealis by toothpick inoculation. Strong pathogenicity strains: WK-19,WK-21,WK-137, intermediate level pathogenicity strains: WK-14,WK-22,WK-195,WK-196, weak pathogenicity strains: WK-32,WK-159,WK-166.2 Use orthogonal test to optimize the cell-wall degrading enzymes production condition. Rhizoctonia cerealis were inducing cultured by improved Marcus liquid medium. The optimal environmental conditions including cultivation time, pH and cultivation temperature were further investigated through orthogonal experiment in this paper. The results showed that: The optimal conditions of cellulose production were 25℃, pH6.8 cultured for 7 days; the optimal conditions of pectinase production were 25℃, pH5.0 for 5 days; the optimal conditions of xylanase production were 25℃, pH6.0 cultured for 5 days.3 Under the optimum conditions, determine the activity of the cell-wall enzymes produced by Rhizoctonia cerealis. The results showed that: the relationgship between pathogenicity and activity of cellulose, pectinase and xylanase is as follows: the enzymes activity of weak pathogenicity strains > strong pathogenicity strains > intermediate level pathogenicity strains.4 Use the strong pathogenicity strain WK-137 and weak pathogenicity strain WK-166, analyze the production dynamics of cellulase, pectinase and xylanase produced by Wheat. The results showed that: cellulase activity begin increase after 6 days inoculated, the peak activity appeared at 10 days after inoculation; the peak activity of wheat inoculated WK-137,WK-166 appeared at 4 days and 6 days after inoculation; the peak xylanase activity of wheat inoculated WK-137 appeared at 2 days after inoculation, followed by lower and produced a small peak at 6 days after inoculation, wheat inoculated WK-166 reached a small peak at 6 days after inoculation. Overall it seems,activity of cell wall degrading enzymes produced by wheat inoculated strong pathogenicity strain WK-137 is higher than wheat inoculated weak pathogenicity strain WK-166.5 Plants after infection by the pathogen, the body's defense enzymes change, to resist pathogen infection. The effects of phenylalanine ammonia lyase and peroxidase synthesis after inoculate different pathogenicity Rhizoctonia cerealis. The results showed that: PAL enzyme activity of wheats inoculated WK-166 and WK-137 is high, so did the wheats non-vaccinated, moreover, three cases of PAL enzyme activity produces no obvious size difference. Wheat inoculate WK-166 2-6 day, POD activity has been generated at a high level, then decreased, while inoculating WK-137 2-6 days, the POD activity generated slightly higher than the non-inoculated wheat, but significantly lower than WK-166 inoculated wheat, and not received after.6 Select each two strains of strong, intermediate level and weak pathogenicity, clone the GH-10 xylanase intermediate gene fragment. Using DNAMAN software Multiple Sequence Alignment analyzes the similarity between these sequences. The results showe that: six strains were classified into four groups: weak pathogenicity strains, intermediate level pathogenicity strains, strong pathogenicity strains WK-19 and strong pathogenicity strains WK-137. there is an obvious polarization of xylanase gene fragment in the middle produced by different virulence strains.
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