Genetic Diversity And Population Genetics Of Termitomyces Fungi From Yunnan

Due to its high diversity of landform, climate, vegetation and ecological type, Yunnan province China has extraordinarily high biodiversity of macrofungi species, including many edible mushrooms with important economic values. Termitomyces fungi, called "Jizongjun" in Chinese, are well known for their symbiotic lifestyle with termites (macrotermitinae) and chicken-like tasty. They originated from Africa and were only transmited into Asia. Up to now, they still can’t be artificially cultivated. Chinese Termitomyces fungi are mainly distributed in Yunnan province, and "Jizongjun" is one of the most important edible mushrooms in Yunnan. However, the pursuit of excessive profits and uncontrolled harvesting practices threaten the natural habitats of the wild populations of "Jizong" in recent years. Understanding genetic diversty and population structure is important for developing sustainable utilization and effective conservation and artificial cultivation of "Jizongjun" in Yunnan.380samples of "Jizongjun" fruitbody were collected from Yunnan. Firstly, we reconstructded phylogenetic relationship and identified phylogenetic species using ribosomal DNA internal transcribed spacer (ITS) and other four single copy genes (RPB2, TEF, Lacc,12s). Secondly, population genetics of one phylogenetic species with the most samples was conducted. The results are as follows:(1) All of the samples were successfully amplified and sequenced using the ITS4and ITS5primer pair.6closely related species (used as reference strains) from Asia and Africa were retrieved from GenBank through comparisons with our sequences. The total380ITS sequences were aligned to a534nucleotides long alignment after aligning by MAFFT version5and selecting conserved blocks by Gblocks.110unique sequence types (genotypes) were identified from the ITS alignment. We used the set composed by110ITS genotype sequences and20reference sequences to reconstruct phylogeny. The phylogenetic tree identified12branches, in which5branches only included our samples,5branches included our samples and reference strains,2branches only included reference sequences.(2) We selected60isolates for genealogical concordance phylogenetic species recognition. We got58RPB2sequences,60TEF sequences,49Lacc sequences,6012s sequences. The phylogenetic tree of RPB2was consistent with the tree of ITS. But the trees for other gene fragments were just partially consistent with ITS’s. The phylogenetic tree of concatenated sequences yielded identical tree topologies and the identified same10branches that were consistent with phylogenetic tree of ITS.(3) Through comparing intra-specific and inter-specific variation of ITS sequences of the six species chosen as references,1.8%was accepted as the highest value of intra-specific variation and2%accepted as the lowest value of inter-specific variation. Taking this value as a threshold, our strains included7new phylogenetic species and3known species.(4) Among the10phylogenetic species, a species with267samples was selected to analyze its population structure and reproductive mode. Finally, we got an available multilocus sequence data for229out of267strains of18populations. The results of population structure revealed that frequent gene flow exist among geographic populations. The results of recombination revealed that significant linkage disequilibrium exist among different gene fragments. Termites may play an important role in the formation of population structure and reproductive mode in natural population of Termitomyces fungi.