地黄属种间亲缘关系研究

对地黄属6个物种进行了形态解剖学观察、染色体计数、核核糖体内转录间隔区(ITS)序列分析.结果表明,茎的高度、幼叶形态、花萼和花冠形态及颜色、种子千粒重和大小、外种皮网壁厚度、外种皮内侧网纹直径等均是该属内分类的可靠依据.高地黄与裂叶地黄在外部形态及解剖结构的各个方面均极为近似,地黄与茄叶地黄间也存在较大的相似性.茄叶地黄、高地黄、湖北地黄、天目地黄的染色体数目,分别为n=28、14、14、14,确认地黄和茄叶地黄为属内四倍体物种,其余种均为二倍体.ITS测序分析显示,地黄属为单系起源,天目地黄与湖北地黄、高地黄与裂叶地黄、地黄与茄叶地黄构成属内3个分支,与形态学及细胞学研究结果一致.研究认为,天目地黄与湖北地黄有较近的亲缘关系;高地黄和裂叶地黄应为同一物种;地黄与茄叶地黄是属内进化水平最高的类群.

Systematic Relationships among Rehmannia (Scrophulariaceae) Species

Morpho-anatomical and cytological studies,molecular analysis were performed on all the six species of Rehmannia.The results showed that the characters of morphology have more taxonomic significance than that of anatomy,such as height of stem,shape of young leaves,shape as well as color of calyx and corolla,1000-seed weight and size of seed,thickness of radial wall of reticulate cells on episperm,and diameter of veins at tangent wall of episperm cells.Shape and anatomic structures extremely resemble between R.elata and R.piasezkii,and the similarity between R.glutinosa and R.solanifolia is also remarkable.Cytological study showed that the chromosome numbers of R.solanifolia,R.elata,R.henryi and R.chingii is n=28,14,14,14 respectively,which confirmed the identity of tetraplonts of R.glutinosa and R.solanifolia,and the rest species diplonts.ITS sequencing indicated that Rehmannia is monophyletic,with R.henryi and R.chingii,R.elata and R.piasezkii,R.glutinosa and R.solanifolia constituting three clades,which coincides with the results of morphology and cytology.Accordingly,R.henryi and R.chingii have closer systematic relationship;R.elata and R.piasezkii are considered to be conspecific;R.glutinosa and R.solanifolia are the advanced groups in Rehmannia.