Abstract:

In order to explore the origin and evolution of tuber mustard（Brassica juncea var. tumida Tsen et Lee），we cloned and sequenced the Chs gene sequences of tuber mustard and its close relative species．As illustrated in the phylogenetic tree，the sequences from all Brassica taxa were separated into three well supported clades and nine sub-clades．Splits tree analysis indicated that there existed not only tree evolution，but also reticulate evolution among tuber mustard and its related plants．Median-joining（MJ）network analysis showed that B. rapa and B. nigra were the parental donors of A genome and B genome in allotetraploid B. juncea tumida，respectively．Tuber mustard，as a variety of B. juncea，was closely related to B. juncea var. utilis，indicating that B. juncea tumida might originate from B. juncea var. utilis．In addition，the single copy gene Chs could be efficiently applied to evaluate the phylogenetic relationships of tuber mustard its and related plants.

Key words: Tuber mustard, Chs gene, Origin and evolution, Molecular systematics

摘要：

为探讨我国茎瘤芥的起源、进化，克隆、测序了30 份茎瘤芥及其近缘种的Chs 基因序列，并构建系统发育树、系统发育网络及网状支系结构。结果表明：系统发育树将茎瘤芥及其近缘种Chs 基因序列分成3 个亚支，9 个支系。系统发育网络分析结果表明，茎瘤芥与其他芥菜变种之间不仅存在树状的进化关系，还大量存在非树状的进化史。网状支系分析结果表明，伊犁野生油菜可能是茎瘤芥A 基因组的供体，黑芥可能是茎瘤芥B 基因组的供体。茎瘤芥为芸薹属芥菜种的一个变
种，与薹芥的亲缘关系较近，可能是由薹芥进化而来。单拷贝的Chs 基因可作为一个理想的候选基因用于茎瘤芥及其近缘植物多倍体系统发育关系的研究。

关键词: 茎瘤芥, Chs 基因, 起源进化, 分子系统学