中国南方地区松乳菇遗传多样性分析

郭亮   刘君昂  周国英  李河

摘  要：松乳菇Lactarius deliciosus是一种对松树的生长具有重大意义的外生菌根真菌，具有很高的经济价值，因无法人工培育，过度的人工采摘造成产地生态的严重破坏。比较中国南方3个省9个不同地区的68个松乳菇的rDNA ITS区碱基序列的差异，以期研究各不同群体的ITS单倍体型多样性，不同地区群体之间的遗传关系，以及遗传分化与地理隔离的关系。遗传分析发现，得到的68个松乳菇样品的ITS序列可认定为7种单倍体型，这些单倍体型聚集为2个不同的系统进化群体，表现出两种不同的系统进化方向。7种单倍体型中，两个主要的单倍体型（Haplotype3和Haplotype6）分别含有34和26个样品，且基本上每个样品采集地都有分布。AMOVA测试中，观察到的总的单倍体型变异频率主要体现在不同地理种群的个体内（84%）。剩下的16%属于不同地理种群间的变异，PhiPT的显著性分析结果p＜0.01。Mantel测试显示地理距离与遗传差异FST值没有显著的线性关系（p=0.32）。研究结果说明松乳菇自然种群间有一定程度的基因漂流发生。群体遗传分析还发现在松乳菇自然种群中存在显著遗传分化，但遗传分化程度与地理距离没有显著的线性关系。

关键词：外生菌根真菌，遗传多样性，遗传分化，基因漂移

Mycosystema

Genetic diversity of Lactarius deliciosus from South China

GUO Liang   LIU Jun-Ang   ZHOU Guo-Ying   LI He

Abstract: Lactarius deliciosus is an ectomycorrhizal mushroom that forms symbiotic associations with species of Pinus and plays an important ecological role in natural forest ecosystems in many parts of the world. It is also an economically important gourmet mushroom. Because no artificial cultivation is available, natural populations of this species are under increasing threats, primarily from habitat disturbance and destruction. We analyzed 68 samples of L. deliciosus from South China using ITS sequences. By comparing the difference of ITS sequences, the haplotype diversity within each population, the relationships among local populations, the relationship between the level of genetic differentiation and geographical separation, and the contributions of local and regional geographical separations to the overall ITS haplotype variation were analysed. Our genetic analysis identified a total of 7 ITS haplotypes and these haplotypes were clustered into two distinct phylogenetic groups, and revealed two different phylogenetic directions. Among the 7 ITS haplotypes, the two major haplotypes (Haplotype3 and Haplotype6) contained 34 and 26 specimens respectively, and distributed in all of the 9 sites. AMOVA test showed that there was significant genetic differentiation at both among local populations (－16%) and within local populations (－84%) levels, and p<0.01 for PhiPT. The Mantel test identified that the extent of genetic differentiation was statistically insignificant correlated with geographical distance (p=0.32). Our study revealed significant genetic divergence within L. deliciosus and detectable gene flow among geographical populations of this ectomycorrhizal mushroom, but the extent of genetic differentiation were insignificant correlated with geographical distance.

Key words: ectomycorrhizal fungi, genetic diversity, genetic divergence, gene flow