亚欧美栗疫病菌群体的遗传多样性

从 12 0个随机引物中筛选出条带清晰、主带明显、重复性好的 9个引物 ,对来自不同地域和寄主的 7个群体的 14 2个栗疫病菌菌株进行 RAPD分析。 9个引物共扩增出条带 12 4条 ,其中多态性条带 111条 ,多态性比率为 89.5 2 %。利用 Popgen3.2软件对供试群体进行遗传多样性分析和 UPGMA聚类。结果表明 ,中国地区 4个群体间的遗传相似性较大 ,与美国、意大利和日本群体间的相似性较小 ;美国和意大利群体间的遗传相似性较大 ,且它们与日本群体间的相似性大于与中国群体间的相似性。病原菌群体的遗传变异率为 0 .2 35 1,其中在地区水平上 ,82 .34%由群体内的变异引起 ,17.6 6 %由群体间的差异引起 ,群体间的基因流动值为 2 .3311;而在寄主水平上 ,则 79.4 2 %由群体内的变异引起 ,2 0 .5 8%由群体间的差异引起 ,群体间的基因流动值为 1.92 97

Genetic diversity of Cryphonectria parasitica populations in Asia, Europe and North America

To study the population structure of the chestnut blight fungus Cryphonectria parasitica, a total of 142 isolates representing seven geological regions including China, Japan, Italy, and the United States were subject to random amplified polymorphic DNAs (RAPDs) analysis. Among the 120 random primers tested, nine were found to generate distinct DNA fragments. Our studies have shown that 89.52% of 124 RAPD fragments were polymorphic and the Jianyang population of China was the most polymorphic (66.94%), whereas the Japanese population was the least polymorphic (37.1%). When analyzed at the host level, gene diversity of total populations (H_T) was estimated at 0.1887. However, the gene diversity occurred mainly within populations (79.42%), not between populations (20.58%). The estimated average gene flow (N_m) between populations was 1.9297 and the ratio of polymorphic RAPD fragments obtained from the populations that have Castanea crenata as the host was the highest (72.58%). Additionally, the gene diversity (H) of the population isolated from C. henryi was highest at 0.2263, whereas the ratio of polymorphic RAPD fragments and gene diversity (H) of the population from C. sativa were among the lowest. Furthermore, the gene diversity of the total populations (H_T) was 0.2351 and that within populations (H_s) was 0.1936 at region level. 82.34% of gene diversity was attributable to the diversity within populations than between populations (17.66%, G_(st)=0.1766). Finally, the gene flow estimate between populations (N_m) was 2.3311, denoting that there was gene flow between populations. Our results conclude that the population gene diversities (H_T) are the greatest in China. The genetic similarities of RAPD frequencies among populations indicate that Chinese populations are similar to each other, but are distinct from populations of Japan, Italy, and the United States. Interestingly, there is less differentiation between Japanese and American populations and between Japanese and Italian populations than that between Japanese and Chinese populations despite the fact that Japan is geographically closer to China.