濒危植物太行菊与长裂太行菊的ITS序列分析

ITS Sequence Analysis of Opisthopappus taihangensis and O. longilobus

对太行菊属(Opisthopappus)的太行菊(O.taihangensis)和长裂太行菊(O.longilobus)13个种群的核糖体DNA ITS进行测序,分析不同种、不同种群间的ITS序列差异。结果表明:排序后的ITS序列总长度为682 bp,含有15个简约信息位点;根据ITS序列差异共确定出18种单倍型,太行菊和长裂太行菊种群均表现出高的单倍型多样性和核苷酸多样性;两个种均有独有的单倍型,又有共有单倍型;聚类分析表明18种单倍型形成明显两支,Hn1和Hn8分别位于两支的中心为祖先单倍型。ITS序列将太行菊和长裂太行菊13个种群聚类成一个单源支系,但长裂太行菊中两个种群(林虑山LLS和石板岩SBY)与太行菊种群聚为一支,显示出两种之间存在着基因交流或杂交。在进化过程中,长裂太行菊可能经历了长距离侵殖,太行菊在太行山隆升之前经历了种群的扩张,随着太行山的隆升逐渐形成现今的分布格局。

The ITS of ribosomal DNA was sequenced to investigate the difference between ITS sequences for 13 populations of Opisthopappus taihangensis(8 populations)and O. longilobus(5 populations)of Opisthopappus. The results indicated that the total length of ITS was 682 bp containing 15 parsimony informative sites. Eighteen nr DNA haplotypes were identified. High haplotype diversity and nucleotide diversity had occurred into O. taihangensis(hd = 0.558,πd = 0.00158)and O. longilobus populations(hd = 0.908,πd = 0.00537). Some haplotypes were unique ones for O. taihangensis and O. longilobus respectively,some were shared by this two species. All indentified haplotypes clustered into two lineages,Hn8 might be an ancestral haplotype for the lineageⅠ,Hn1 was the predominant and widespread one in the cladeⅡ. The all studied populations of O. taihangensis and O. longilobus was gathered a monophyletic clade. Five O. longilobus populations were not gathered together,LLS and SBY of O. longilobus were gathered together with all eight O. taihangensis populations which indicated exchange of genes or interspecific hybridization occurred between O. taihangensis and O. longilobus. During the process of evolution,long-distance dispersal and colonization may be a major historical event for O. longilobus;A pattern of population expansion and re-colonization was observed in O. taihangensis before the uplift of Taihang Mountains.