Liu Xinrui, Wu Xiaoping, Tan Hao, Xie Baogui, Deng Youjin
College of Life Science, Fujian Agriculture and Forestry University, Fuzhou, Fujian 350002, China.
Mushroom Research Center, Soil and Fertilizer Institute, Sichuan Academy of Agricultural Sciences, Chengdu 610000, China.
Comput Struct Biotechnol J. 2020 Sep 2;18:2424-2437. doi: 10.1016/j.csbj.2020.08.022. eCollection 2020.
Genomic structure and content of mitochondrial DNA contain essential information regarding the evolution of this gourmet mushroom. In this study, eight isolates of were sequenced and assembled into complete mitochondrial genomes. The mtDNA of the isolate Ag0067 contained two genotypes, both of which were quadripartite architecture consisting of two identical inverted repeats, separated by a small single-copy region and a large single-copy region. The only difference was opposite directions of the small single-copy region. The mtDNAs ranged from 116,329 bp to 134,035 bp, harboring two large identical inverted repeats. Genes of plasmid-origin were present in regions flanked by inverted repeat ID2. Most of the core genes evolved at a relatively low rate, whereas five tRNA genes located in corresponding regions of Ag0002:1-14000 and Ag0002:50001-61000 showed higher diversity. A long fragment inversion (10 Kb) was suggested to have occurred during the differentiation of two main clades, leading to two different gene orders. The number and distribution of the introns varied greatly among the mtDNAs. Fast invasion of short insertions likely resulted in the diversity of introns as well as other non-coding regions, increasing the variation of the mtDNAs. We raised a model about the evolution of the large repeats to explain the unusual features of mtDNAs. This study constructed quadripartite architecture of mtDNAs analogous to chloroplast DNA, proposed an interconversion model of the divergent mitochondrial genotypes with large inverted repeats. The findings could increase our knowledge of fungal evolution.
线粒体DNA的基因组结构和内容包含了有关这种美味蘑菇进化的重要信息。在本研究中，对八个分离株进行了测序并组装成完整的线粒体基因组。分离株Ag0067的线粒体DNA包含两种基因型，两者均为四分体结构，由两个相同的反向重复序列组成，中间被一个小单拷贝区域和一个大单拷贝区域隔开。唯一的区别是小单拷贝区域的方向相反。线粒体DNA的长度在116,329 bp至134,035 bp之间，含有两个大的相同反向重复序列。质粒起源的基因存在于反向重复序列ID2侧翼的区域。大多数核心基因的进化速度相对较低，而位于Ag0002:1-14000和Ag0002:50001-61000相应区域的五个tRNA基因显示出更高的多样性。在两个主要分支的分化过程中，可能发生了一个长片段倒位（10 Kb），导致了两种不同的基因顺序。内含子的数量和分布在这些线粒体DNA之间差异很大。短插入片段的快速侵入可能导致了内含子以及其他非编码区域的多样性，增加了线粒体DNA的变异。我们提出了一个关于大重复序列进化的模型来解释这些线粒体DNA的异常特征。本研究构建了类似于叶绿体DNA的四分体结构的线粒体DNA，提出了具有大反向重复序列的不同线粒体基因型的相互转换模型。这些发现可以增加我们对真菌进化的了解。
