Biotechnology and Nuclear Technology Research Institute, Sichuan Academy of Agricultural Sciences, Chengdu 610061, Sichuan, PR China; Key Laboratory of Bio-Resource and Eco-Environment of Ministry of Education, College of Life Sciences, Sichuan University, Chengdu 610065, Sichuan, PR China.
Biotechnology and Nuclear Technology Research Institute, Sichuan Academy of Agricultural Sciences, Chengdu 610061, Sichuan, PR China.
Int J Biol Macromol. 2019 Jan;121:249-260. doi: 10.1016/j.ijbiomac.2018.10.029. Epub 2018 Oct 9.
Lactarius is one of the most prominent genera of mushroom-forming fungi in the world. In the present study, complete mitochondrial genomes (mitogenomes) from six Lactarius species were sequenced and assembled. The six mitogenomes were all composed of circular DNA molecules, with total lengths ranging from 38,445 bp to 60,843 bp. The GC contents, GC skews, and AT skews of the mitogenomes varied among the six species. Mitogenomic synteny analysis revealed the presence of gene rearrangements among the mitogenomes. Among the 15 core protein coding genes (PCGs) within the mitogenomes, nad4L exhibited the least genetic distance among species, indicating a high degree of conservation. In addition, the Ka/Ks values for all 15 core PCGs were <1, suggesting that they were subject to purifying selection. Comparative analyses indicated that the increase of intron numbers and sizes contributed to the expansion of mitogenomes in Lactarius. Phylogenetic analyses based on three combined gene datasets yielded identical and well-supported (BPP ≥ 0.83) topologies, dividing the six Lactarius species into two groups. This study provides the first report of mitogenomes from Lactarius and promotes further understanding of the genetics, evolution, and phylogenetic relationships of this important ectomycorrhizal fungal genus.
乳菇属是世界上最主要的蕈菌类真菌属之一。在本研究中，我们对六个乳菇物种的完整线粒体基因组（mitogenomes）进行了测序和组装。这六个 mitogenomes 均由圆形 DNA 分子组成，总长度从 38445bp 到 60843bp 不等。六个物种的 mitogenomes 的 GC 含量、GC 偏斜和 AT 偏斜存在差异。线粒体基因组的协同分析显示，mitogenomes 之间存在基因重排。在 mitogenomes 内的 15 个核心蛋白编码基因（PCGs）中，nad4L 在物种间表现出最小的遗传距离，表明其高度保守。此外，所有 15 个核心 PCGs 的 Ka/Ks 值均<1，表明它们受到纯化选择的影响。比较分析表明，内含子数量和大小的增加导致了乳菇属 mitogenomes 的扩张。基于三个联合基因数据集的系统发育分析产生了相同的、支持度高（BPP≥0.83）的拓扑结构，将六个乳菇物种分为两组。本研究首次报道了乳菇属的 mitogenomes，促进了对这个重要的外生菌根真菌属的遗传学、进化和系统发育关系的进一步理解。
