Hainan Key Laboratory for Sustainable Utilization of Tropical Bioresources, College of Tropical Crops, Hainan University, Haikou, 570228, China.
School of Integrative Plant Science, Section of Plant Biology and the L.H. Bailey Hortorium, Cornell University, Ithaca, NY, 14850, USA.
BMC Ecol Evol. 2021 May 28;21(1):103. doi: 10.1186/s12862-021-01827-4.
The Styracaceae are a woody, dicotyledonous family containing 12 genera and an estimated 160 species. Recent studies have shown that Styrax and Sinojackia are monophyletic, Alniphyllum and Bruinsmia cluster into a clade with an approximately 20-kb inversion in the Large Single-Copy (LSC) region. Halesia and Pterostyrax are not supported as monophyletic, while Melliodendron and Changiostyrax always form sister clades. Perkinsiodendron and Changiostyrax are newly established genera of Styracaceae. However, the phylogenetic relationship of Styracaceae at the generic level needs further research.
We collected 28 complete plastomes of Styracaceae, including 12 sequences newly reported here and 16 publicly available sequences, comprising 11 of the 12 genera of Styracaceae. All species possessed the typical quadripartite structure of angiosperm plastomes, with sequence differences being minor, except for a large 20-kb (14 genes) inversion found in Alniphyllum and Bruinsmia. Seven coding sequences (rps4, rpl23, accD, rpoC1, psaA, rpoA and ndhH) were identified to possess positively selected sites. Phylogenetic reconstructions based on seven data sets (i.e., LSC, SSC, IR, Coding, Non-coding, combination of LSC + SSC and concatenation of LSC + SSC + one IR) produced similar topologies. In our analyses, all genera were strongly supported as monophyletic. Styrax was sister to the remaining genera. Alniphyllum and Bruinsmia form a clade. Halesia diptera does not cluster with Perkinsiodendron, while Perkinsiodendron and Rehderodendron form a clade. Changiostyrax is sister to a clade of Pterostyrax and Sinojackia.
Overall, our results demonstrate the power of plastid phylogenomics in improving estimates of phylogenetic relationships among genera. This study also provides insight into plastome evolution across Styracaceae.
安息香科是一个木质的、双子叶植物科，包含 12 个属和大约 160 个种。最近的研究表明，安息香属和四合木属是单系的，杨桐属和伯乐树属在大单一拷贝（LSC）区有一个大约 20kb 的倒位。秤锤树属和珙桐属不支持单系，而领春木属和长果安息香属总是形成姐妹群。伯乐树属和长果安息香属是安息香科的新建立的属。然而，安息香科在属水平上的系统发育关系需要进一步研究。
我们收集了 28 个完整的安息香科质体基因组，包括 12 个新报告的序列和 16 个公开可用的序列，包括安息香科的 12 个属中的 11 个属。所有物种都具有被子植物质体基因组的典型四分体结构，序列差异较小，除了在杨桐属和伯乐树属中发现一个大约 20kb（14 个基因）的倒位。鉴定出 7 个编码序列（rps4、rpl23、accD、rpoC1、psaA、rpoA 和 ndhH）具有正选择位点。基于 7 个数据集（即 LSC、SSC、IR、编码、非编码、LSC+SSC 组合和 LSC+SSC+一个 IR 的串联）的系统发育重建产生了相似的拓扑结构。在我们的分析中，所有属都被强烈支持为单系。安息香属是其余属的姐妹群。杨桐属和伯乐树属形成一个分支。秤锤树属二倍体不与伯乐树属聚类，而伯乐树属和珙桐属形成一个分支。长果安息香属与珙桐属和四合木属形成一个姐妹群。
总的来说，我们的结果表明质体基因组学在提高属间系统发育关系估计方面的强大功能。本研究还为安息香科的质体进化提供了见解。
