外生菌根真菌土生空团菌种群遗传多样性与结构研究

土生空团菌Cenococcum geophilum是生态系统中广泛分布的外生菌根真菌,具有丰富的遗传多样性和重要的生态功能。为揭示土生空团菌的种群遗传多样性和结构,本研究对采集自中国10个森林地点的桦木科Betulaceae、壳斗科Fagaceae和松科Pinaceae植物根系219份样品高通量测序的土生空团菌ITS2序列进行分析。结果表明4 380条土生空团菌ITS2序列共划分为137个单倍型（Hap_1-Hap_137）,其中Hap_1是3科植物的优势单倍型并分布于所有地点,有48个单倍型分布于少数几个地点,但有88个单倍型仅分布于单个地点。非参数（Kruskal-Wallis）检验结果表明地点对土生空团菌单倍型的丰度和多样性具有显著影响,而宿主植物科对其无显著影响。分子方差分析（AMOVA）结果显示土生空团菌在10个地理种群间和3个植物科种群间的遗传分化均不明显,而遗传分化主要来自于种群内的个体差异。基于K-2P遗传距离的邻接法（NJ）树显示10个地理种群可以划分为3支,壳斗科土生空团菌种群的遗传距离比桦木科和松科远。土生空团菌单倍型组成在不同地点间和不同植物科间均有明显差异,有些土生空团菌单倍型具有地点和植物科的偏好性。研究结果为进一步揭示土生空团菌遗传多样性的生态功能提供科学依据。

Population genetic diversity and structure of ectomycorrhizal fungus Cenococcum geophilum

Cenococcum geophilum, as one of the common ectomycorrhizal fungi, is widely distributed in various ecosystems and has highly genetic diversity and important ecological function. The population genetic diversity and structure of C. geophilum were analyzed based on internal transcribed spacer 2 (ITS2) sequences of 219 root samples collected from the plants of Betulaceae, Fagaceae and Pinaceae in 10 Chinese forest sites, using high-throughput sequencing techniques. In total, 137 haplotypes (Hap_1-Hap_137) were obtained from 4 380 ITS2 sequences of C. geophilum. Of these haplotypes, Hap_1 was dominant in the plants of Betulaceae, Fagaceae and Pinaceae and occurred in all sampling sites; 48 haplotypes distributed in a few sites, and 88 haplotypes occurred only in one site. Kruskal-Wallis test showed that not host plant family but sampling site significantly affected the haplotype richness and diversity of C. geophilum. The analysis of molecular variance (AMOVA) showed that genetic differentiation was evident within each geographical population and population in each host plant family. The neighbor-joining tree based on K-2P genetic distance showed that 10 geographical populations of C. geophilum were divided into 3 groups, and genetically C. geophilum population in Fagaceae was distant from population in Betulaceae and Pinaceae. The haplotype composition of C. geophilum was conspicuously different in the 10 sampling sites and 3 plant families, and some common haplotypes showed remarkably strong preferences for site and plant family. Further revealing the ecological function of the genetic diversity of C. geophilum is needed.