Diversity Of Tree Canker And Electrophoretic Karyotype Analysis Of Typical Strains

Tree canker is a kind of most serious tree trunk disease which have a various of pathogens,a wide distribution of host and complex symptoms.The samples of tree canker were gathered from Beijing,Jiangsu province,Inner Mongolia province,Shandong province,Henan province,Guangdong Jiangmen,Shanxi province and so on.,then the pathogenic fungi were isolated,cultured, identified and its diversity was.analysed;the DNA isolation and preparation of strains A, B and C of poplar canker was studied for the first time and the optimum produce condition was verified,and karyotype of the three strains was studied, the results as follows: 1. 130 pathogenic strains were isolated from the 20 species of tree canker samples of poplars and poplar clones,eucalypt etc,which from Beijing, Jiangsu, Inner Mongolia,Shandong,Henan,Guangdong Jiangmen and Shanxi, which were identified Dothiorella,Fusicoccum,Cytospora,Fusarium,Pestolotia,Phomopsis and Dothichiza 7 species of fungi through ultrastructure studies on their samples and fruit-bodies.We found for the first time in China that Fusicoccum species could infect eucalypts and cause canker on stems. The eucalypt is a new host for Fusicoccum species and the biological and physiological characteristics were studied in the paper. 2. The studies of extraction and culture conditions optimization of chromosomal DNA strains (A,B,C) isolated from typical canker samples of Shannxi and Liaoning province showed that mycelium produced high quantity and quality chromosomal DNA when cultured 4～5d ,at the water temperature of 35℃,pH6.0 and 6~8h treatment with 2% cell wall degrading enzyme prepared by 0.6mol/L Magnesium sulfate solution. 3. The preliminary studies on electrophoretic karyotype of the pathogenic strains A, B and C showed that there were at least two same-size chromosomes in A and B strains, the molecular weights of which were 1125kb and above 2200kb respectively.