基于SSU序列的串珠藻目植物系统发育分析

通过18S rDNA基因(SSU)序列,构建了串珠藻目植物的系统发育关系.结果显示:SSU基因序列片段长度为1 871 bp,核苷酸变异位点有709个,占序列长度的38％；其中简约信息位点有169个,占序列长度的9％.用最大似然法、邻接法和贝叶斯法构建的系统树拓扑结构基本一致,都显示红索藻目的2个属独立于串珠藻目成单独分支,支持红索藻目的建立；胶串珠藻独立于其他串珠藻组植物,支持将其单独分组；数据同时支持将扭曲组和杂生组合并,建立Kumanoa属；但多芒组、绿色组、沼生组等因分子序列数据涉及的种类较少,其系统关系的确定还需要更多的证据.

Phylogeny of Batrachospermales (Florideophyceae,Rhodophyta) Inferred from Small-Subunit rDNA Gene Sequences

Batrachospermales is an order belonging to Florideophceae,Rhodophyta.It distributes all over the world.China and its adjacent regions are the distribution center.The small-subunit rDNA gene (SSU) sequences from species of Batrachospermales and their relative lineages were used to reconstruct the phylogenetic trees by using the PAUP^* 4.0b10 and MrBayes 3.1.2 software,which contained 12 samples collected from China and 28 species abroad obtained from GenBank.The results showed that the SSU region sequence was 1 871 bp with 709 variation sites (38%) and 169 parsimony informative sites (9%).The phylogenetic relationships were inferred using the maximum-likelihood,neighbor-joining,and Bayesian analysis,and three methods produced trees with largely congruent topology.All phylogenetic trees topology got a similar placement of Thoreales,which formed a monophyletic group with high bootstrap support.According to the Bayesian analysis,the conclusion supported that the Thoreales should be classified as a separate order.Three trees all revealed that Batrachospermum gelatinosum is separated from other members of Sect.Batrachospermum and should be classified as a separate Section.The genus Kumanoa should be admitted based on Sect.Contorta and Sect.Hybrida.