分子证据支持蓝药蓼和大铜钱叶蓼归入冰岛蓼属

Transferring of Polygonum cyanandrum and P. forrestii to Koenigia according to molecular evidence

蓝药蓼Polygonum cyanandrumDiels和大铜钱叶蓼P.forrestii Diels是否应归于冰岛蓼属Koenigia至今未得到很好的解决。本文利用叶绿体DNA的atpB-rbcL序列来评价这两个物种的亲缘关系和属的归属。对这两个物种以及相关代表种的atpB-rbcL序列分析发现,该片段的长度有较大的变异,从753bp到902bp;存在丰富的系统发育变异位点。系统发育分析表明:蓝药蓼和大铜钱叶蓼与冰岛蓼K.islandica聚为支持率较高的分支。而蓼属Polygonum代表种和其他属的代表种组成另外的分支,表明这两个种应置于冰岛蓼属。这一结果与花粉和染色体证据相吻合。根据这些证据以及形态学特征,还对冰岛蓼属与蓼属的范围与界定进行了讨论。

It has been debated whether two Polygonum species, P cyanandrum Diels and P forrestii Diels, should be transferred to Koenigia. In the present paper, nucleotide variations of the chloroplast atpB-rbcL noncoding spacer were examined for these two species and related representatives from the Polygonaceae. The atpB-rbcL spacer region varies among sampled species with a range from 753 to 902 bp, and the great variation in this region provides enough information for evaluating the phylogenetic relationships of the two investigated species. In contrast to the view that these two species belong to Polygonum, our phylogenetic analyses based on these molecular data showed that P cyanandrum and P forrestii were nested within a well supported clade including Koenigia islandica; the other three Polygonum species grouped with species of different genera. These results suggest that the two species should be transferred to Koenigia from Polygonum, and that phylogenetic relationships among Polygonum and related genera need to be further investigated with increased taxon sampling and gene markers. The resulting phylogeny is consistent with the previous suggestions based on pollen and chromosome investigations. The generic circumscription between Koenigia and Polygonum is also discussed in light of these results in combination with gross morphology.