中国槭属植物的分类和系统发育研究

槭属(Acer Linn.)是槭树科(Aceraceae)中物种形态高度分化和分类处理十分困难的一个属。该属的系统发育、属下分类系统以及部分种的系统位置仍未明确。测定了槭属11个组47种植物53份样品的nrDNA ITS和cpDNA序列(matk、rbcL、trnH-psbA和trnL-trnF),并从Gen Bank下载9个组14个种的35条序列,构建了中国分布槭属的分子系统发育树,并对槭属组下分类系统以及部分争议种的分类地位进行了验证。结果发现:前人将鸡爪槭组、小果槭组和全缘叶槭组中的羽脉槭系合并为一个组是合理的;(2)中国槭属有3条进化支系,其中鸡爪槭组、尖齿槭组、穗状槭组、蔹叶槭组和梣叶槭组处于一条进化支系,槭组、茶条槭组、扁果槭组、全缘叶槭组、三小叶槭组和五小叶槭组处于第2条进化支系,桐状槭组、大花槭组和坚果槭组处于第3条进化支系;(3)槭属的性别分化、花序类型、花序着生方式、单复叶类型以及单叶的分裂数可以作为槭属系统发育研究的重要形态指标;(4)通过ITS条形码构建的系统关系,滇藏槭与传统形态分类不相符合;(5)支持将橄榄槭修订为秀丽槭,而锐齿槭、羊角槭、多果槭和昌化槭等的系统位置仍需进一步探讨。

Studies on the Taxonomy and Molecular Phylogeny of Acer in China

Acer Linn.,a highly diversified genus with more than 200 species in the Aceraceae,has been an very difficult group in both taxonomical and phylogenetic studies.The infrageneric phylogeny,classification and systematic positions of some species remain unclear for this genus.The main objective of this study was to examine infrageneric relationships of Acer as inferred from molecular evidence against the traditional classification on the basis of the morphological characteristics.In addition,we intended to investigate the systematic position of some controversial species,as well as to reconstruct phylogeny of this genus.In this study,the nuclear ribosomal ITS region and four chloroplast regions (matk,rbcL,trnH-psbA and trnL-trnF) were sequenced or downloaded for 61 species in Acer,representing the 15 sections in Fang'system (1981).It was indicated that the revisions of Sect.Palmata,Sect.Microcarpa and Sect.Integrifolia in Xu'system (2008) were correct,which were supported by the species clusters.Based on cluster analysis and morphological data,three evolutionary branches of Acer were inferred.Sect.Palmata,Sect.Arguta,Sect.Spicata,Sect.Cissifolia and Sect.Negundo belong to the same evolutionary branch,Sect.Acer,Sect.Ginnala,Sect.Hyptiocarpa,Sect.Integrifolia,Sect.Trifoliata and Sect.Pentaphylla were located in another evolutionary branch,and Sect.Platanoidea,Sect.Macrantha and Sect.Lithocarpa were clustered in the third evolutionary branch.In addition,some morphological indicators,such as sexuality,inflorescence type,leaf shape,and leaflets number were proved important for studying infrageneric phylogeny of this genus.Our results also demonstrated that A.olivaceum should be better treated as a synonym of A.elegantulum,while the systematic positions of A.wardii,A.hookeri,A.yangjuechi,A.prolificum,and A.changhuaense require further study.