In the majority of sexual eukaryotes, the mitochondrial genomes are inherited uniparentally. As a result, individual organisms are homoplasmic, containing mitochondrial DNA (mtDNA) from a single parent. Here we analyzed the mitochondrial genotypes in Clade I of the gourmet mushroom Thelephora ganbajun from its broad geographic distribution range. A total of 299 isolates from 28 geographic locations were sequenced at three mitochondrial loci: the mitochondrial small ribosomal RNA gene, and the cytochrome c oxidase subunits I (COX1) and III (COX3) genes. Quantitative PCR analyses showed that the strains had about 60-160 copies of mitochondrial genomes per cell. Interestingly, while no evidence of heteroplasmy was found at the 12S rRNA gene, 262 of the 299 isolates had clear evidence of heterogeneity at either the COX1 (261 isolates) or COX3 (12 isolates) gene fragments. The COX1 heteroplasmy was characterized by two types of introns residing at different sites of the same region and at different frequencies among the isolates. Allelic association analyses of the observed mitochondrial polymorphic nucleotide sites suggest that mtDNA recombination is common in natural populations of this fungus. Our results contrast the prevailing view that heteroplasmy, if exists, is only transient in basidiomycete fungi.
[1]Yunnan Univ, State Key Lab Conservat & Utilizat Bioresources Y, Kunming, Yunnan, Peoples R China.
[2]Kunming Med Univ, Affiliated Hosp 2, Dept Key Lab, 374 Dian Mian Rd, Kunming 650101, Yunnan, Peoples R China.
[3]Yunnan Inst Trop Crop Res, Jinghong 666100, Yunnan, Peoples R China.
[4]Guizhou Prov Ctr Dis Control & Prevent, Inst Communicable Dis Control & Prevent, Guiyang 550004, Guizhou, Peoples R China.
[5]Hainan Med Coll, Publ Res Lab, Haikou 570000, Hainan, Peoples R China.
[6]Hainan Med Coll, Inst Trop Dis Res, Haikou 570000, Hainan, Peoples R China.
[7]McMaster Univ, Dept Biol, Hamilton, ON L85 4K1, Canada.
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