Analysis Of Genetic Diversity Of Fusarium Oxysporum F. Sp.Cubense In Guangdong And The Screening Of Chitinase-producing Bacteria Against Them

In order to study the population subdivision and genetic variation of Fusarium oxysporum f. sp. cubense in Guangdong Province, universal primers ITS1and ITS4for race identification and phylogentic analysis and amplified fragment length polymorphism (AFLP) were used to analyze the DNA fingerprint of isolates from Zhuhai, Zhanjiang and Taishan. Based on the phylogentic analysis of banana fusarium wilt pathogen, the typical high virulence isolate were choose to screen antagonistic bacteria which had the chitinase-producing ability. The results were as follows:1. The AFLP results showed that a total of253AFLP bands were obtained using8primer combinations, and97of them, covering38.34%, showed polymorphism. Genetic distance of21isolates ranged from0.41to0.95, averaged0.85. Results of UPGMA analysis divided21tested isolates into three major groups, which was race1, race4and non-pathogenic F. oxysporum, this result was consistent with the phylogenetic analysis on the cloned rDNA-ITS sequences. AFLP analysis revealed that the diversity level of race1was greater than that of race4and there was a correlation between AFLP groups and geographic origin of tested isolates. The results indicated that the genetic diversity of F. oxysporum f. sp. cubense was high among tested isolates from Zhuhai.2. According to rDNA-ITS and AFLP analysis, strain FOC009of race4which has the most strong ability to produce toxin was chosen as the representative fungi for screening chitinase-producing bacteria. By using the fungi cell rich medium and analyzing the capacity of hydrolysis.14chitinase-producing bacteria were screened, and strain CA3, CA5, CA11, CA34had antagonistic function on FOC009, the inhibit ratio were48.30%,47.13%,37.65%and41.66%, respectively. Their16S rDNA were cloned and after bioinformational analysis, they were identified as Paenibacillus, Bacillus and Cellulosimicrobium cellulans.