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【目的】从分子水平上揭示我国枣树干腐病菌群体的遗传特点,探究其遗传变异的规律。【方法】采用正交实验设计的方法,对影响ISSR-PCR扩增的4个因素进行研究。采用ISSR分子标记,对161株供试病原菌进行PCR扩增,通过Pop Gene和Arlequin软件对其群体遗传多样性和遗传分化情况进行分析。【结果】从40条ISSR引物中筛选到10条扩增多态性良好的引物,建立了适合枣树干腐病菌ISSR-PCR扩增的体系。采用该体系共在132个位点扩增出条带,其中多态性位点129个,多态性位点百分率为97.93%。Pop Gene结果显示,在物种水平上,供试病原菌的基因多样性指数和Shannon信息指数分别为0.256 3和0.397 8。分子方差分析表明,不同地理种群间的遗传变异占总变异量的7.94%,不同地理种群内的各自然种群间的遗传变异占总变异量的24.46%,自然种群内各分离株的遗传变异占总变异量的67.58%。聚类分析结果表明,在遗传相似系数为0.19时,可将9个病原菌自然种群划分为6个不同的聚类群。【结论】我国枣树干腐病菌(B.dothidea)群体具有丰富的遗传多样性,群体内多样性大于群体间多样性。自然种群内各分离株的遗传变异是我国枣树干腐病菌遗传变异的主要来源。我国枣树干腐病菌的各自然种群之间的遗传亲缘关系与其地理来源无明显相关性。
【Objective】 To reveal the genetic characteristics of juvenile dry-rot population in jujube in China at molecular level and to explore the law of its genetic variation. 【Method】 Four factors influencing ISSR-PCR amplification were studied by orthogonal experiment design. ISSR molecular markers were used to amplify 161 tested pathogenic bacteria and their population genetic diversity and genetic differentiation were analyzed by Pop Gene and Arlequin software. 【Result】 Ten primers were screened from 40 ISSR primers for amplifying ISSR-PCR. Using this system, a total of 132 bands were amplified, of which 129 were polymorphic and the percentage of polymorphic loci was 97.93%. Pop Gene results showed that the genetic diversity index and Shannon information index of tested pathogens were 0.256 3 and 0.397 8 respectively at the species level. Molecular variance analysis showed that the genetic variation among different geographical populations accounted for 7.94% of the total variation, and the genetic variation among the natural populations within different geographic populations accounted for 24.46% of the total variation. The genetic variation among the isolates within the natural population accounted for The total variation of 67.58%. Cluster analysis showed that at the genetic similarity coefficient of 0.19, nine natural populations of pathogenic bacteria could be divided into six different clusters. 【Conclusion】 B.dothidea populations in China are rich in genetic diversity, with greater diversity within populations than among populations. The genetic variation of all the isolates in the natural population is the main source of genetic variation of the Chinese jujube tree rot pathogen. The genetic relationship between the natural populations of the Chinese jujube stem rot pathogens had no significant correlation with their geographical origins.