中国落叶松-杨栅锈菌遗传多样性研究

采用SSR分子标记技术对采自全国19个地区、不同年份的落叶松-杨栅锈菌Melampsora larici-populina(简称MLP)36个单孢子堆菌系的遗传多样性和种群遗传结构进行了研究。用5对SSR多态性引物共检测到62个观察等位基因(Na),有效等位基因数(Ne)为5.42-9.82,平均有效等位基因数为7.05。供试MLP样本在5个SSR位点上的多态性信息量(PIC)变化范围为0.64-0.89,平均值0.79。平均观察杂合度(Ho)、平均期望杂合度(He)分别为0.36和0.86,不同位点的Shannon’s信息指数(I)平均值为2.12。结果显示,中国MLP菌系具有丰富的遗传多样性。各MLP菌系群体间遗传分化系数(Fst)变化范围为0.22-0.39,平均值0.344,基因流(Nm)平均值为0.48,显示遗传变异主要出现在MLP菌系群内部(65.60%),尤其以采自天然林的菌系群最为明显,但各菌系群之间也存在着明显的遗传分化(34.40%)。在菌系地理群体水平上,Shannon’s信息指数、Nei’s遗传多样性指数(Nei’s)平均值分别为1.02和0.56,平均多态性位点数(Np)和多态位点百分率(PPL)分别为4.54和90.77%,反映出MLP地理群之间的遗传多样性较菌系群内部的遗传多样性低。依据菌系地理群之间的遗传距离(0.24-2.99),将供试的13个中国落叶松-杨栅锈菌菌系群分为4个类群:菌群Ⅰ由北京延庆、太白山厚畛子、秦岭火地塘和四川宝兴诸菌系组成;菌群Ⅱ由吉林长春、黑龙江哈尔滨与肇东、甘肃临夏和青海诸菌系组成;菌群Ⅲ由内蒙古呼和浩特、陕西周至和杨凌的菌系组成;菌群Ⅳ由陕西宝鸡天台山和太白山上白云菌系组成。

Genetic diversity of poplar rust fungus Melampsora larici-populina in China

Melampsora larici-populina(abbr.MLP) is a heteroecious fungal pathogen causing foliar rust on Populus and Larix species.The genetic diversity of 36 isolates of MLP,collected from 19 locations of eight provinces in China in different years,was investigated by simple sequence repeat(SSR) analysis.A total of 62 alleles for five SSR loci were detected from 91 samples within 36 isolates of MLP,and the effective number of alleles(Ne) ranged from 5.42 to 9.82,with an average of 7.05.The polymorphism information content(PIC) for five loci ranged from 0.64 to 0.89,with an average of 0.79.The average values of observed heterozygosity(Ho) and expected heterozygosity(He) were 0.36 and 0.86,respectively,and Shannon's information index(I) varied from 1.88 to 2.52,with an average of 2.12.These results showed that all the test MLP isolates were very rich in genetic diversity.The coefficient of gene differentiation among isolate populations(Fst) varied from 0.22 to 0.39,with an average of 0.344,and the average value of gene flow(Nm) was 0.48,which revealed that the genetic diversity appeared mainly within isolate populations(65.60%),specially between isolate populations of MLP from natural forest areas,but also showed distinct differentiation of genetics among isolate populations(34.40%).At geographical population level,the average I and Nei's gene diversity(Nei's) were 1.02 and 0.56,respectively,and average values of polymorphic loci(Np) and percentage of polymorphic loci(PPL) were 4.54 and 90.77%,respectively,implying that the genetic diversity among geographical populations was relatively lower than that within isolate populations of MLP.Based on Nei's genetic distance,ranging from 0.24 to 2.99,13 geographical populations of MLP isolates from different regions in China could be initially grouped into four clusters:cluster I included isolates By,Th,HD and Sb,cluster II included isolates Cj,HZ,Gl and Qh,cluster III included isolates Nm,Wh and Yl,and cluster Ⅳcomprised Ts and Tt.