Pathogenicity Differention And RAPD Analysis Of Cercospora Zeay-maydis In Jilin Province

In this study, 38 isolates of cercospora zeay-maydis, mainly isolated from corn gray leaf spot in different geographic regions in Jilin, which were characterized by 9 differential host and random amplified polymorphic DNA(RAPD). The results showed that there was abundant genetic diversity and pathogenicity differentiation in these isolates. No close correlation was found between genetic diversity and geographic origins of isolates. Meanwhile, Corn cultivar were evaluated for resistance to gray leaf spot of corn in Jilin province. The major results are as follows:1,Through two years of investigating we acknowledge the development trend of gray leaf spot of corn in jilin province. We found there were two different leaf lesion, one was slender and the other was the typical lesion. There may be different genetic differentiation type or pathogenic difference. In order to understand the various pathogenic types or genetic differentiation type distribution rule, we expanded the investigation area, and we get 38 isolates by separated and purified the disease spot.2,14 isolates of Cercospora zeay-maydis, mainly isolated from corn gray leaf spot in different geographic regions in Jilin province, which were characterized by 9 differential host. The results showed that the progress levels of symptom were different after the different Cercospora zeae-maydis infection. The type of host reaction has polymorphism. The aggressivity was different between every isolates. Fourteen isolates were classified into five pathogenicity groups by the different aggressivity .â… was the highest virulence to host,â…£was the weakest one andâ…¡â…¢were the middles.,â…¤were 12,13,14 .The result provided a basis for scientifically planting resistant cultivars in growing areas and breeding resistant cultivars.3,38 strains of Gray Leaf Spot of Corn were isolated from corn leaves in different district of Jilin Province, which were characterized by random amplified polymorphic DNA(RAPD). The result shows that there are significant genetic differences in these isolates. Through the RAPD profiles obtained by cluster analysis found that all of the strains in the similarity coefficient of about 0.55 together as a group, the similarity coefficient of about 0.68into 5 groups, and group 2 strains accounted for a total of 30 measured 78.9% of the total strain. The pathogen of regional genetic is not obvious. 4,Through measuring the amount of spores in different media, different training days, different carbon source conditions, we got the best medium V8 and MLPA, and the optimal carbon sucrose, and the best training day 7d.48 cultivars and 19 inbreds were collected to assess their resistance to Cercospora zeae-maydis by artificial inoculation at the adult stage in the field. Four highly resistant hybrids and three resistant inbreds were screened for the disease resistance. The result provided a basis for scientifically planting resistant cultivars in growing areas and breeding resistant cultivars.