Ma Chuan, Hu Ruoyang, Costa Cecilia, Li Jianke
Institute of Apicultural Research, Chinese Academy of Agricultural Sciences, Beijing, China.
CREA Research Centre for Agriculture and Environment, Bologna, Italy.
Front Genet. 2022 Feb 9;13:835967. doi: 10.3389/fgene.2022.835967. eCollection 2022.
Mitochondrial genomes (mitogenomes) are involved in cellular energy metabolism and have been shown to undergo adaptive evolution in organisms with increased energy-consuming activities. The genetically selected high royal jelly-producing bees (RJBs, ) in China can produce 10 times more royal jelly, a highly nutritional and functional food, relative to unselected Italian bees (ITBs). To test for potential adaptive evolution of RJB mitochondrial genes, we sequenced mitogenomes from 100 RJBs and 30 ITBs. Haplotype network and phylogenetic analysis indicate that RJBs and ITBs are not reciprocally monophyletic but mainly divided into the RJB- and ITB-dominant sublineages. The RJB-dominant sublineage proportion is 6-fold higher in RJBs (84/100) than in ITBs (4/30), which is mainly attributable to genetic drift rather than positive selection. The RJB-dominant sublineage exhibits a low genetic diversity due to purifying selection. Moreover, mitogenome abundance is not significantly different between RJBs and ITBs, thereby rejecting the association between mitogenome copy number and royal jelly-producing performance. Our findings demonstrate low genetic diversity levels of RJB mitogenomes and reveal genetic drift and purifying selection as potential forces driving RJB mitogenome evolution.
线粒体基因组（mitogenomes）参与细胞能量代谢，并且已证实在能量消耗活动增加的生物体中会经历适应性进化。在中国，经过基因筛选的高产蜂王浆蜜蜂（RJBs）相较于未经过筛选的意大利蜜蜂（ITBs），能生产出营养丰富且具有多种功能的蜂王浆，产量高出10倍。为了测试RJB线粒体基因的潜在适应性进化，我们对100只RJB和30只ITB的线粒体基因组进行了测序。单倍型网络和系统发育分析表明，RJB和ITB并非相互单系的，而是主要分为以RJB为主和以ITB为主的亚谱系。以RJB为主的亚谱系在RJB中的比例（84/100）比在ITB中的比例（4/30）高6倍，这主要归因于遗传漂变而非正选择。由于纯化选择，以RJB为主的亚谱系表现出较低的遗传多样性。此外，RJB和ITB之间的线粒体基因组丰度没有显著差异，因此否定了线粒体基因组拷贝数与蜂王浆生产性能之间的关联。我们的研究结果表明RJB线粒体基因组的遗传多样性水平较低，并揭示了遗传漂变和纯化选择是驱动RJB线粒体基因组进化的潜在因素。
