Phylogenetic relationships of golden camellias (sect.Chrysantha,Camellia)in China: evidence from ITS sequences of nuclear ribosomal DNA
Phylogenetic relationships of golden camellias (sect.Chrysantha,Camellia)in China: evidence from ITS sequences of nuclear ribosomal DNA
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作者：
Tang Shao-qing
【摘要】：金花茶属于山茶科(Camellia)山茶属,分布于中国南部和越南北部的狭小地区,是著名的观赏植物和商业栽培的有用遗传资源,但近十年来其系统发育关系一直存在争议。本文通过对PCR扩增DNA片段直接测序，确定了中国菊科22个分类单元的核糖体DNA内转录间隔区（ITS）的核苷酸序列，以及作为外类群的中国菊科C.sinensis。中国金花科ITS1和ITS2区域总长度为476~496个碱基对(bp),22个分类单元中GC含量均超过70%。采用木村二参数模型估计序列分歧，并采用最大简约法（MP）、邻接法（NJ）和最大似然法（ML）进行系统发育分析。 ITS数据表明(1)C.longruiensis、C.longgangensis、C.ptilosperma、C.flavida、C.impressinervis和C.grandis亲缘关系较近；(2)C.parvipeta、C.multipetala、C.chrysanthoides、C.micriantha、C.xiashiensis和C.longzhouensis亲缘关系较近。
Golden camellias,belonging to the genus Camellia(Theaceae)and distributed in a narrow region of southern China and northern Vietnam,are very famous ornamental plants and useful genetic resources for commercial cultivation,but their phylogenetic relationships have been controversial during the recent decade. In this paper,the nucleotide sequences of the internal transcribed spacer(ITS)of nuclear ribosomal DNA in 22 taxa of the sect.Chrysantha in China and C.sinensis of the sect.Thea as an outgroup were determined by direct dequencing of PCR-amplified DNA fragments. The total length of the ITS1 and ITS2 regions of the sect.Chrysantha in China ranged from 476 to 496 base pairs(bp),and the GC content was over 70% in the 22 taxa. Sequence divergences were estimated using Kimura two-parameter model,and the phylogenetic analysis were performed using the maximum parsimony(MP),the neighbor-joining(NJ),and the maximum likelihood(ML)methods. The ITS data suggest (1)C.longruiensis,C.longgangensis,C.ptilosperma,C.flavida,C.impressinervis and C.grandis are closely related;(2)C.parvipeta,C.multipetala,C.chrysanthoides,C.micriantha,C.xiashiensis,and C.longzhouensis have closed relationship.