国产驴蹄草的细胞地理学研究

为探讨国产毛茛科(Ranunculaceae)驴蹄草属(Caltha)两种植物的演化,该文利用传统染色体压片技术和流式细胞术,并结合前人染色体研究结果,对我国驴蹄草23个居群和花葶驴蹄草10个居群进行了细胞学研究。结果表明:驴蹄草是由四倍体(2n=4x=32)、六倍体(2n=6x=48)和八倍体(2n=8x=64)构成的多倍体复合群,花葶驴蹄草具有四倍体(2n=4x=32)和八倍体(2n=8x=64)两种倍性水平。驴蹄草和花葶驴蹄草均是四倍体较为常见,目前尚未见有二倍体报道。由于驴蹄草和花葶驴蹄草大部分居群采自中国青藏高原地区,可能在冰期时存在古二倍体,其适应性较弱,逐渐被其他的倍性取代,这是由于不同细胞型对环境适应性的结果。驴蹄草可能存在两条进化路线:一条是从甘肃到达云南;另一条是从西藏到达云南。前期分子系统学研究显示花葶驴蹄草与驴蹄草的亲缘关系较近,该研究结果中花葶驴蹄草染色体比驴蹄草要小,花葶驴蹄草可能比驴蹄草相对进化。目前花葶驴蹄草只有10个居群,还需进一步增加居群量来解析其演化路线。

Cytogeography of Caltha palustris (Ranunculaceae)from China

Twenty-three Caltha palustris accessions and ten C. scaposa accessions have been cytologically investigated using the traditional chromosome tableting technique and flow cytometry(FCM), in order to investigate the evolution of C. palustris and C. scaposa in Caltha of Ranunculaceae. C. palustris was found to be a polyploid complex, which contained tetraploids(2n=4x=32), hexaploids(2n=6x=48), and octoploids(2n=8x=64), and C. scaposa were tetraploids(2n=4x=32)and octoploids(2n=8x=64). Tetraploids were common in C. palustris and C. scaposa, however, any diploids were hardly discovered. This finding may be explained by cytotype adaptive differences to the underlying heterogeneity of environmental factors. Most accessions of C. palustris and C. scaposa were from extreme habitats, such as the alpine mountains in the Qinghai-Tibetan Plateau. Ancestral diploids may have existed in this region during glacial periods and colonized most regions at the end of the glaciation cycles. However, individuals with other ploidy levels may gradually replace diploids, because of their increased fitness in changing environment. Moreover, there were two possible evolutionary colonization routes: one from Gansu to Yunnan, and the other from Tibet to Yunnan of China. Molecular phylogeny have shown that C. scaposa is closely related to C. palustris, the chromosome size of C. scaposa is smaller than that of C. palustris, C. scaposa may be a relatively derived evolutionary taxon. More samples need to be analyzed in the future to better elucidate C. scaposa cytogeography because of only ten accessions.