基于叶绿体psaA和psbA基因的中国熊野藻属植物系统发育分析

以中国产熊野藻属Kumanoa的两个种, 绞扭熊野藻K. intorta (=绞扭串珠藻Batrachospermum intortum), 弯形熊野藻K. curvata (=弯形串珠藻B. curvatum)和其他6种淡水红藻为实验材料, 对其psaA和psbA基因进行扩增和测序, 并与GenBank中相近序列进行比对分析, 以贝叶斯法、最大似然法和邻接法分别构建了单基因和联合基因系统发育树. 结果表明, 3种方法构建的系统树具有相似的拓扑结构, 反映的系统发育关系基本一致, 熊野藻属中的两个种聚为一支, 与串珠藻属相分离, 支持该属的建立; 中国产的熊野藻属分子学研究结果与来自南美洲及澳洲的该属植物结果一致, 说明该属的建立具有广泛的地理适用性. 系统发育树聚类结果也明确反映了熊野藻属与串珠藻属较近的亲缘关系, 根据果胞枝形态特点, 推测熊野藻属进化地位晚于串珠藻属植物, 而早于顶丝藻目和红索藻目. 此外, 胶串珠藻与其他串珠藻组植物分离, 支持将其单独分组, 红索藻目植物与串珠藻目植物分离, 支持红索藻目的建立. 同时也表明psaA和psbA基因用于淡水红藻分析, 能够较好地反映其系统发育关系.  

Phylogenetic relationship of genus Kumanoa based on chloroplast Psaa and psba genes

Kumanoa intorta (former Batrachospermum intortum) and K. curvata (former B. curvatum) are two species of genus Kumanoa originally from China. In this study we amplified and sequenced the chloroplast psaA and psbA genes of these two species and of other six freshwater Rhodophyta species. We aligned their sequences with related groups from GenBank, and constructed phylogenetic trees of both single gene and combined genes by using the methods of Bayesian analysis, maximum likelihood and neighbor-joining. The trees generated with three different methods showed similar topologies and thus inferred consistent phylogenetic relationships. The two species from genus Kumanoa could form one clade with high supportive values but should be separated from genus Batrachospermum. The analysis above supported our report about a new genus Kumanoa. The molecular biological study of Kumanoa species originally from China revealed similar results with those originally from South America and Australia, indicating wide geographical areas of this genus. The phylogenetic tree demonstrated a close relationship between genus Kumanoa and Batrachospermum. According to the characteristics of the carpogonial branch, we deducted that the evolution of genus Kumanoa was later than that of Batrachospermum, but earlier than that of Acrochaetiales and Thoreales. B. gelatinosum should be separated from other section Batrachospermum species and be classified as an independent section. The construction of the order Thoreales could be supported by the fact that Thoreales and Batrachospermales should be separated. Furthermore, our study suggested that psaA and psbA genes could be used as molecular markers in the study of the phylogenetic relationships of Rhodophyta.