纽芬兰鸡油菌群体遗传多样性的主要影响因素分析

Analyses of genetic diversity reveal major forces impacting a local population of the gourmet mushroom Cantharellus enelensis

纽芬兰鸡油菌是北美东部一种深受欢迎的美味食用菌。火烧山,位于加拿大格罗莫恩国家公园中心、三面环水,该地纽芬兰鸡油菌的持续出菇时间至少可追溯至20世纪60年代且未见于周边地区。研究该持续存在的孤立种群,对于资源保护和开发具有重要意义。本研究在火烧山共采集纽芬兰鸡油菌子实体109个,包括间距100 m以上的6个局域群体共81个个体以及5 d后随机采集的28个个体。基于微卫星标记的基因分型结果显示,3个位点上分别有3、5和2个等位基因,而每个局域群体的各位点均被1到2个等位基因主导;共有多位点基因型29个。每个局域群体和总样本中的基因型频率总体上符合哈迪-温伯格平衡。虽然总样本中存在显著的遗传分化,但克隆校正后未检测到差异。比较间隔5d的两次取样,等位基因和基因型频率存在微小差异。此外,与纽芬兰岛另外两地(分别相距约200 km和600 km)和安大略省哈密尔顿市一地(约2000 km外)共3个地区群体样本进行了比较。结果表明,突变、有性生殖、基因流、选择和遗传漂变都对纽芬兰鸡油菌种群的遗传多样性产生了影响。

Cantharellus enelensis is a popular edible mushroom in eastern North America.Burnt Hill(BH),a small hill surrounded by water on three sides in the heart of Gros Morne National Park of Canada,has been consistently producing fruiting bodies of C.enelensis since at least the 1960s.In contrast,the surrounding areas are not known to produce any fruiting body of this species.Understanding how such an isolated population persists has significant conservation and economic importance.In this study,we obtained and analyzed the genotypes of 109 fruiting bodies from BH,among which,81 were collected from six patches separated by more than 100 m from each other and the remaining 28 were randomly collected five days later throughout the hill.Genotyping based on microsatellite markers revealed three,five and two alleles at the three loci respectively,with each local patch dominated by one to two alleles at each locus.The three markers revealed 29 multilocus genotypes(MLGs)among the 109 fruiting bodies.The genotype frequencies at each local patch population and in the total sample were overall consistent with Hardy-Weinberg equilibrium.Among the six local patches,while the total samples showed statistically significant genetic differentiation,no difference was observed among the clone-corrected samples.Comparisons between samples from the two time points separated by five days revealed minor differences in allele and genotype frequencies.In addition,we compared the BH population with those at two other sites in Newfoundland(~200 km and~600 km away)and one site in Hamilton,Ontario(~2000 km away)to identify potentially unique alleles and genotypes at BH.Together,our analyses demonstrated that mutation,sexual reproduction,gene flow,selection,and genetic drift have all contributed to the genetic diversity within this local chantarelle population.