松乳菇ITS序列比较及其在乳菇属中的系统发育分析

Comparison of Lactarius deliciosus ITS Sequences and Phylogenetic Analysis of the Genus Lactarius

提取江苏、云南、江西、湖南、广西、安徽、湖北地区的松乳菇(Lactarius deliciosus)、红汁乳菇(L.hatsudake)、橙色乳菇(L.akahatsu)和鲑色乳菇(L.salmonicolor)共25个子实体样本的基因组DNA,扩增ITS序列,对GenBank下载和本次及以前测序的松乳菇ITS序列的碱基组成、变异位点及碱基替换类型进行分析,从GenBank下载乳菇属其它8个种,构建乳菇系统发育树。结果显示:松乳菇ITS序列共有20 bp长度的变化,碱基C、T含量大于G、A含量。变异位点ITS共有99个(ITS1 58个、5.8S 4个、ITS2 37个),其中主要是T与C的转换,转换与颠换位点数分别为8和5。ITS1、5.8S、ITS2中转换与颠换的比值R分别为2.34、1.95、1.12。基于ITS序列计算不同地区松乳菇间的遗传距离,江西与意大利、西班牙,法国与西班牙序列间的遗传距离最大为0.012,云南和法国序列间遗传距离为0,是同源序列。系统发育树显示:松乳菇和红汁乳菇、橙色乳菇亲缘关系较近。

ITS sequences were amplified by PCR using genomic DNA extracted from fruit bodies of Lactarius deliciosus , L . hatsudake , L . akahatsu and L . salmonicolor originating from different geographical regions for the purpose of comparing ITS variation and analyzing phylogeny in the genus Lactarius. Base compositions, variable sites and base substitution types of L. deliciosus ITS sequences were determined and a phylogenetic tree was constructed. Maximal variation among all the L. deliciosus sequences was 20 bp, and the percentage of C/T was higher compared with A/G. ITS sequences contained 99 variable sites （TS1.. 58; 5.8S：4; ITS2..37）, eight transitional and five transversional sites, and the transition between T and C was the main variant type. R values for 1TS1, 5.8S and ITS2 were 2.34, 1.95 and 1.12, respectively. Genetic distances between L. deliciosus samples from different regions were calculated based on the ITS sequences; the maximal genetic distance （0. 012） was recorded between samples from Jiangxi and Italy, Jiangxi and Spain, and France and Spain. The minimal genetic distance （zero） was recorded between samples from Yunnan and France, the ITS sequences of which were homologous. Phylogenetic analysis revealed a close relationship between L. deliciosus, L. hatsudake and L. akahatsu.