| This study focus on Cirtus Bacterial Canker Disease (CBCD) in China, Hunan province.16S rRNA and gyrB sequence primer are used to PCR amplified and sequencing the collected strains. The genetic differentiation of CBCD form different regions and different host plants in Hunan area was analysised. Then some strains with obivious difference according to the genetic distance were choosen, their resistance to2main fungicide was tested. Finally experimental results are following.1. Collected CBCD injected plants tissue in Hongjiang, Shuangfeng, Hengnan, Shimen, Lingling, Yongxing, Pingjiang, Chaling of Hunan. By isolated and indentificated by specific primer, ensured22reliable and representative CBCD strains.2. Amplificated their16S rRNA and gyrB sequences, sequencing and clustering analyse them with Unweighted Pair Group Method with Arithmatic mean, UPGMA. It shows that the isolated strains can be classified to3groups by16S rRNA sequencing when genetic distance is0.0045. However, by gyrB sequence analysis, Those strains turn to groups individually expect two form Chaling when genetic distance is0.0045.The sensitivity of gyrB sequence analysis is higher than16S rRNA’s. which can not only tell the difference of close exogenous strains, but also further classificate strains belong to one class from different sources.3. Selected7strains with different genetic distance gotten in above experiment, tested their sensitivity to common copper fungicide:Thiodiazole copper and Kocide, by mean of inhibition zone and enumeration of colonies on agar media. The result shows that both fungicide have certain inhibition to all7strains, but the degree of inhibition is little different between each other. The average EC50of Thiodiazole copper to7strains is37.36μg/ml(Max:44.64μg/ml, Min:34.20μg/ml), while Kocide’s is91.55μg/ml(Max:108.72μg/ml, Min:77.92μg/ml). There are no obivious resistance of7strains to both fungicides, neither high resistance mutant. |
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