Abstract
In the present study, we assembled and compared two mitogenomes from the Rhizopogon genus. The two mitogenomes of R. salebrosus and R. vinicolor comprised circular DNA molecules, with the sizes of 66,704 bp and 77,109 bp, respectively. Comparative mitogenome analysis indicated that the length and base composition of protein coding genes (PCGs), rRNA genes and tRNA genes varied between the two species. Large fragments aligned between the mitochondrial and nuclear genomes of both R. salebrosus (43.41 kb) and R. vinicolor (12.83 kb) indicated that genetic transfer between mitochondrial and nuclear genomes has occurred over evolutionary time of Rhizopogon species. Intronic regions were found to be the main factors contributing to mitogenome expansion in R. vinicolor. Variations in the number and type of introns in the two mitogenomes indicated that frequent intron loss/gain events occurred during the evolution of Rhizopogon species. Phylogenetic analyses based on Bayesian inference (BI) and Maximum likelihood (ML) methods using a combined mitochondrial gene set yielded identical and well-supported tree topologies, wherein Rhizopogon species showed close relationships with Agaricales species. This is the first study of mitogenomes within the genus Rhizopogon, and it provides a basis for understanding the evolution and differentiation of mitogenomes from the ectomycorrhizal fungal genus.
Highlights
The genus Rhizopogon, (Boletales, Basidiomycota), is an important ectomycorrhizal fungal group, which was widely distributed in Europe and North America [1,2,3,4,5]
Int.TJ.hMeol.cSocmi. 2p01le9,t2e0,mx FitOoRgPeEnEoRmREeVsIEoWf R. salebrosus and R. vinicolor were composed of circula3rofD16NA molecules, with the total size of 66,704 bp and77,109 bp, respectively (Figure 1)
We found that mitogenomes of the two Rhizopogon species were of medium size, smaller than those of Phlebia radiate [30,39], A. bisporus [30] and Lentinula edodes [40], and larger than those of Coprinopsis cinerea [41] and Schizophyllum commune [42], which all belonged to the Agaricomycotina
Summary
The genus Rhizopogon, (Boletales, Basidiomycota), is an important ectomycorrhizal fungal group, which was widely distributed in Europe and North America [1,2,3,4,5]. No mitochondrial genomes have been assembled from sequence data in the genus, which limits our understanding of this important ectomycorrhizal fungal group. Mitochondria are the main chemical energy suppliers for aerobic, free-living eukaryotes, and play an important role in growth, development, aging and stress resistance [14,15] Mitochondria contain their own genomes, commonly known as the "second genome" of eukaryotes [16], and hereafter referred to as mitogenomes. Previous studies found that mitogenomes of fungi differed greatly in genome size, content of repeat sequence, gene arrangement, and genome organization [25,26,27]. The mitogenomes of the two Rhizopogon species in this study further our understanding of the genetics, taxonomy, and evolutionary biology of the ectomycorrhizal fungi, and other related fungal species
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