应用核DNA ITS序列探讨广义花楸属(Sorbus L.)属下系统关系

A Molecular Phylogeny of Sorbus(Rosaceae)Based on ITS Sequence

花楸属属内杂交和多倍化现象比较普遍,分类处理一直存在争议。选取核基因的ITS序列对花楸属(Sorbus L.)的46个种进行测序,并选取栒子属(Cotoneaster multiforus,Cotoneaster horizontalis)、白鹃梅属(Exochorda racemosa)、蔷薇属(Rosa hugonis)和樱属(Cerasus glandulosa)作为外类群,基于最大简约分析(Maximum parsimony analysis,MP),最大似然分析(Maximum likelihood analysis,ML)和贝叶斯推断(Bayesian inference,BI)对花楸属进行分子系统发育重建。结果表明:花楸属为自然的单系类群,并且得到很高的支持率;Aria、Micromeles和Sorbus,3个亚属各自不能形成单系,甚至单叶类群和复叶类群的分类学界限都不是很清楚,这说明目前的分子系统发育证据与花楸属属内的分类划分并不十分吻合。

The systematic circumscription of Sorbus has remained unresolved because of hybridization and polyploidy.To reconstruct the phylogeny of Sorbus,we sequenced the nuclear ribosomal DNA ITS region of 46 species of the genus and outgroups species Cotoneaster multiforus,Cotoneaster horizontalis,Exochorda racemosa,Rosa hugonis and Cerasus glandulosa.The phylogenetic relationships among 43 species of Sorbus were investigated by means of maximum parsimony（MP）,maximum likelihood（ML）and bayesian inference（BI）analyses.The results revealed that the genus Sorbus is monophyletic;Subg.Aria,Subg.Micromeles and Subg.Sorbus were not monophyletic,respectively;The circumscription between unifoliate group and multifoliate group is unclear.The results are not in accordance with the previous morphological classification.