Wang Yue, Xu Jianping
Department of Biology, McMaster University, Hamilton, ON, Canada.
Institute of Bast Fiber Crops and Center of Southern Economic Crops, Chinese Academy of Agricultural Sciences, Changsha, China.
Front Microbiol. 2020 Apr 21;11:706. doi: 10.3389/fmicb.2020.00706. eCollection 2020.
The complex consists of at least seven evolutionary divergent lineages and causes ∼200,000 fatal human infections each year worldwide. The dominant lineage is which consists of three haploid clades VNI, VNII, and VNB, their haploid hybrids, and various diploids derived from intra- and inter-clade mating events. In this study, we analyzed the mitogenomes of 184 strains of . Our analyses revealed that all 184 mitogenomes contained the same 15 protein-coding genes in the same gene order. However, their mitogenome sizes varied between 24,740 and 31,327 bp, primarily due to differences in the number and size of mitochondrial introns. Twelve nucleotide sites within five mitochondrial genes were found to contain introns in at least one of the 184 strains, ranging from 2 to 7 introns within each mitogenome. The concatenated mitochondrial exon sequences of the 15 protein-coding genes and two rRNA genes showed that VNI, VNII, and VNB strains were separated into distinct clades or sub-clades, largely consistent with results based on nuclear genome SNPs. However, several novel findings were observed. First, one strain of the VNB clade contained mitogenome exon sequences identical to the main VNI mitogenome type but was distant to other VNB mitogenomes. Second, hybrids among clades VNI, VNII, and VNB identified based on their nuclear genome SNPs contained mitogenomes from different clades, with evidence of their mitogenomes inherited from either the or the parents. Third, the eight diploid VNB () × VNIV () hybrids contained recombinant mitogenomes. Fourth, analyses of intron distribution and the paired exon-intron phylogenies for each of the 12 exon-intron pairs suggested frequent gains and losses of mitochondrial introns during the evolution of . The combined mitogenome exon-based phylogeny and intron distributions suggested that clades VNI, VNII and VNB could be further divided into sub-clades. Together, our results revealed a dynamic evolution of mitochondrial genomes in this important human fungal pathogen.
该复合体由至少七个进化上不同的谱系组成，在全球范围内每年导致约20万例致命的人类感染。主要谱系是 ，它由三个单倍体分支VNI、VNII和VNB、它们的单倍体杂种以及源自分支内和分支间交配事件的各种二倍体组成。在本研究中，我们分析了184株 的线粒体基因组。我们的分析表明，所有184个线粒体基因组都以相同的基因顺序包含相同的15个蛋白质编码基因。然而，它们的线粒体基因组大小在24,740至31,327 bp之间变化，主要是由于线粒体内含子的数量和大小不同。在五个线粒体基因中的12个核苷酸位点被发现至少在184个菌株中的一个中含有内含子，每个线粒体基因组中内含子的数量从2到7个不等。15个蛋白质编码基因和两个rRNA基因的串联线粒体外显子序列表明，VNI、VNII和VNB菌株被分为不同的分支或亚分支，这在很大程度上与基于核基因组SNP的结果一致。然而，观察到了几个新发现。首先，一株VNB分支的菌株包含与主要VNI线粒体基因组类型相同的线粒体基因组外显子序列，但与其他VNB线粒体基因组距离较远。其次，基于核基因组SNP鉴定的VNI、VNII和VNB分支之间的杂种包含来自不同分支的线粒体基因组，有证据表明它们的线粒体基因组是从 或 亲本遗传而来的。第三，八个二倍体VNB（ ）×VNIV（ ）杂种包含重组线粒体基因组。第四，对12个外显子-内含子对中每一对的内含子分布和配对外显子-内含子系统发育分析表明，在 的进化过程中线粒体内含子频繁获得和丢失。基于线粒体基因组外显子的系统发育和内含子分布的综合分析表明，VNI、VNII和VNB分支可以进一步分为亚分支。总之，我们的结果揭示了这种重要的人类真菌病原体中线粒体基因组的动态进化。
