基于SSR序列的江西省不同生态地区稻瘟病菌遗传多样性分析

为明确江西省稻瘟病菌Magnaporthe oryzae群体遗传结构及其多样性水平,选用13对SSR引物对分离自5个不同生态地理县(市)水稻穗颈瘟标样的稻瘟病菌单孢菌株的全基因组进行PCR扩增,利用最长距离法和POPGENE 32生物学软件对其进行聚类分析和群体遗传多样性分析。结果显示,共分离获得189株稻瘟病菌菌株,13对SSR引物对其均能扩增出1条大小相同且清晰的条带,多态性位点百分率高达100.00%。供试189株稻瘟病菌菌株在相似系数为0.74时可划分为15个遗传宗谱,其中宗谱JXL01包含71株菌株,占总菌株数的37.57%,为优势宗谱;宗谱JXL02、JXL14为亚优势宗谱,分别包含31、26株菌株,占总菌株数的16.40%和13.76%;宗谱JXL03、JXL08、JXL10为次要宗谱,包含10～17株菌株;其它9个宗谱为小宗谱,包含菌株都在5株以下。在群体水平上,来源于不同生态型地区的5个稻瘟病菌群体的Nei’s基因多样性指数为0.375,Shannon信息指数为0.558,具有丰富的遗传多样性,且群体间差异较大;这5个种群基于非加权配对平均法大多聚为一类,种群遗传谱系与地理区域分布呈一定相关性,群体遗传多样性均值为0.373,存在一定的遗传分化,且群体内多样性大于群体间多样性,总遗传变异的64.56%存在于群体内。表明江西省稻瘟病菌群体结构既包含明显的优势宗谱,又存在复杂多变的特异性小宗谱,遗传多样性丰富,且与地理分布有一定的相关性。

Genetic diversity analysis of rice blast fungus in different ecological regions of Jiangxi Province in China based on SSR

In order to clarify the genetic structure and diversity level of Magnaporthe oryzae populations in Jiangxi Province, 13 pairs of SSR primers were used to cluster analysis and population genetic diversity analysis of M. oryzae from five different ecological counties (cities) based on complete linkage method by biological software of POPGEN 32. The results showed that total 189 strains were separated, the specific products could be amplified clearly with all primer pairs, and the polymorphic loci was 100.00%. The 189 tested strains were divided into 15 genetic lineages at a similarity coefficient of 0.74. Among them, JXL01 was the dominant lineages, which contained 71 strains, accounting for 37.57% of the total strains. JXL02 and JXL14 were sub-dominant lineages containing 31 and 26 strains with the percentage of 16.40% and 13.76% respectively. JXL03, JXL08 and JXL10 were secondary lineages, containing the strain from ten to 17. The other nine lineages were minor lineages and contained fewer than five strains. At the group level, the Nei''s genetic diversity index and Shannon''s information index of five populations were 0.375 and 0.558, which indicated the existence of rich genetic diversity in M. oryzae populations from different geographic regions. Most populations from the above five regions were clustered into one group, which meant that the genetic lineages of the populations from different areas were related to their geographic distributions. And meanwhile, certain genetic differentiation existed in the same M. oryzae population (total heterozygosit was 0.373). The genetic diversity of within-population was higher than that of among-population, and 64.56% of the total heritable variation in within-population. Overall, populations of M. oryzae in Jiangxi Province were rich in genetic diversity with both dominant and variable minor lineage, and it exists in certain correlation with geographical distribution.