The complete mitochondrial genomes of the nematode-trapping fungus Arthrobotrys oligospora.

Arthrobotrys oligospora is a potential candidate of biocontrol agents against plant and animal parasitic nematodes. In this study, the complete mitochondrial genome of A.oligospora was sequenced. This mitogenome is a circular molecule of 160,613 bp in length. Gene annotation showed that 44 putative protein-coding genes and 24 tRNAs, all located on the same strand. The evolutionary relationships between A. oligospora and other representative ascomycetes were revealed based on sequences at the 14 concatenated mitochondrial protein-coding genes.

The complete mitochondrial genome of the nematode-trapping fungus Dactylellina haptotyla.

The complete mitochondrial genome of Dactylellina haptotyla was studied in this study. This mitogenome is a closed circular molecule of 146,101 bp in length with a GC content of 22.92%, including 14 protein-coding genes, 26 transfer RNA genes, 2 ribosomal RNA genes. Phylogenetic analyses based on sequences at the 14 concatenated mitochondrial protein-coding genes showed that D. haptotyla was closely related to Pyronema omphalodes.

Frequent heteroplasmy and recombination in the mitochondrial genomes of the basidiomycete mushroom Thelephora ganbajun.

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.

The complete mitochondrial genome of the edible Basidiomycete mushroom Phlebopus Portentosus.

The complete mitochondrial genome of Phlebopus portentosus was determined using Illumina sequencing. The circular genome is 42,963 bp in length with GC content of 21.37%. It contains 14 putative protein-coding genes, the ribosomal RNA subunits and 23 tRNAs, all located on the same strand. The evolutionary relationships between P. portentosus and other 23 representative basidiomycete species were revealed based on sequences at the 14 concatenated mitochondrial protein-coding genes.

Evidence for Inbreeding and Genetic Differentiation among Geographic Populations of the Saprophytic Mushroom Trogia venenata from Southwestern China.

During the past 40 years, more than 400 Sudden Unexplained Deaths (SUDs) have occurred in Yunnan, southwestern China. Epidemiological and toxicological analyses suggested that a newly discovered mushroom called Trogia venenata was the leading culprit for SUDs. At present, relatively little is known about the genetics and natural history of this mushroom. In this study, we analyzed the sequence variation at four DNA fragments among 232 fruiting bodies of T. venenata collected from seven locations. Our ITS sequence analyses confirmed that all the isolates belonged to the same species. The widespread presence of sequence heterozygosity within many strains at each of three protein-coding genes suggested that the fruiting bodies were diploid, dikaryotic or heterokaryotic. Within individual geographic populations, we found significant deviations of genotype frequencies from Hardy-Weinberg expectations, with the overall observed heterozygosity lower than that expected under random mating, consistent with prevalent inbreeding within local populations. The geographic populations were overall genetically differentiated. Interestingly, while a positive correlation was found between population genetic distance and geographic distance, there was little correlation between genetic distance and barium concentration difference for the geographic populations. Our results suggest frequent inbreeding, geographic structuring, and limited gene flow among geographic populations of T. venenata from southwestern China.

Orbilia tianmushanensis sp. nov., a new member of the O. luteorubella group with an unusual asexual morph.

A new species of Orbilia related to O. luteorubella is described mainly based on morphological characters of its asexual morph and molecular data. The sexual morph does not significantly differ from O. luteorubella, whereas the asexual morph obtained from its ascospore isolate resembles members of the non-predacious genus Dactylella, because it has fusiform phragmoconidia borne singly at the apex of conidiophores. Phylogenetic analysis showed that this strain clustered with a clade that included available strains of the O. luteorubella aggregate and was distant from all analysed Dactylella species. Within this clade, the new strain fell between species with filiform conidia and those of a Pseudotripoconidium anamorph. By combining morphological and phylogenetic analyses, we conclude that our isolate belongs to a new taxon. Pleomorphism of the new taxon is described and discussed.