基于叶绿体基因组的蔷薇科水榆属系统发育分析及分类处理

Phylogenetic analysis and taxonomic treatment of Micromeles (Rosaceae) based on chloroplast genomes

关键词:  蔷薇科，水榆属，叶绿体基因组，系统发育，分类处理

Key words:  Rosaceae, Micromeles, chloroplast genome, phylogeny, taxonomic treatment

摘要:

水榆属（Micromeles Decne.）隶属于蔷薇科（Rosaceae），具有单叶及果期萼片脱落的显著特征，广泛分布于亚洲地区，全世界约有33种，我国约有28种。为明确水榆属分类地位，该研究运用高通量测序技术，新测18个水榆属物种叶绿体基因组序列，并结合NCBI已发表数据，共135份（代表134个物种），以最大似然法和贝叶斯推断法构建水榆属叶绿体基因组系统发育树，并结合历史研究，界定水榆属的分类地位。结果表明：（1）传统意义上的水榆属（单叶，果期萼片脱落）不是单系，与白花楸属（Aria (Pers.) Host）（单叶、果期萼片宿存）亚洲分布种类聚为一支，并与狭义花楸属（羽状复叶）形成姐妹群。（2）白花楸属欧洲分布的种类与红花楸属（Chamaemespilus Medik.）和驱疝木属（Torminalis Medik.）聚为一支，该分支与枫棠属（Eriolobus (DC.) M. Roem.）亲缘关系近。（3）系统发育研究结果支持将白花楸属亚洲分布种归入水榆属，而欧洲的部分物种应继续保持在白花楸属内。（4）基于系统发育结果和参考文献，本文支持扩大范围的水榆属为单系、且独立的属，并对其物种范围进行了界定，共包含59个物种，其中包含4个新组合名称：Micromeles chengii (C. J. Qi) Meng Li & C. F. Tian, comb. nov.、Micromeles eleonorae (Aldosoro et al.) Meng Li & C. F. Tian, comb. nov.、Micromeles kohimensis (Watt ex C. B. Clarke) Meng Li & C. F. Tian, comb. nov.、Micromeles verticillata (Merr.) Meng Li & C. F. Tian, comb. nov.。该研究为蔷薇科苹果族的系统演化提供了重要的依据。

Abstract:

The genus Micromeles Decne. belongs to Rosaceae, and characterized by simple leaves and without persistent sepals when fruiting. Micromeles is widely distributed in Asia, with approximately 33 species recognized globally and 28 species occurring in China. To clarify the classification status of Micromeles, this study sequenced 18 chloroplast genomes of Micromeles using high-throughput sequencing and integrated these new data with publicly available sequences. This yielded a final dataset of 135 chloroplast genomes representing 134 species. Based on this dataset, the chloroplast genome phylogenetic tree of Micromeles was constructed via maximum likelihood and bayesian inference. The results were as follows: (1) Micromeles in traditional sense (simple leaves, fruits without persistent sepals) is non-monophyletic, but clustered into a clade with Asian-distributed Aria (Pers.) Host (simple leaves, fruits with persistent sepals) and formed a sister group with Sorbus s.s. (2) The European-distributed species of Aria, Chamaemespilus Medik. and Torminalis Medik. were clustered together and more closely related to Eriolobus (DC.) M. Roem. (3) Phylogenetic study results support incorporating the Asian-distributed species of the genus Aria into the genus Micromeles. In contrast, the European-distributed species featuring persistent sepals should be retained within Aria. (4) We re-delimited the genus Micromeles based on our plastome phylogenomics and findings from literature references. Then, made taxonomic treatment for Micromeles in Asia, and confirmed that this genus contains 59 species, including 4 new combinations (Micromeles chengii (C.J. Qi) Meng Li & C. F. Tian, comb. nov.、Micromeles eleonorae (Aldosoro & al.) Meng Li & C.F. Tian, comb. nov.、Micromeles kohimensis (Watt ex C.B. Clarke) Meng Li & C. F. Tian, comb. nov.、Micromeles verticillata (Merr.) Meng Li & C. F. Tian, comb. nov.). This research provides significant evidence for the systematics and evolution of the Maleae in Rosaceae.