Phylogenetic Study Of Eriocaulaceae In Monocotyledons Based On RbcL Sequences Analysis

So many same or similar morphological characters among Eriocaulaceae, Xyridaceae, Commelinaceae, Juncaceae and Poaceae ,meanwhile Eriocaulaceae has its own exclusive characters, make the taxonomy of Eriocaulaceae very difficult. And it's also difficult to ensure the relationship between Eriocaulaceae and the relatived families.In recent years, the fasting growing molecular systematics revitalized the plant systematics and have gained great achievement.While sometimes,the study about Eriocaulaceae based on molecule didn't consistent with those of classical taxonomy.In this study, 6 species from Eriocaulaceae, Xyridaceae, Commelinaceae, Juncaceae were collected as material. The controversive choloplast gene rbcL were used to sequencing analysis and construct phylogenetic trees. Fininally, combining to the morphological characters , the taxonomy of Eriocaulaceae and the relationship among these families were studied,which could prove the existing result both from morphological and molecular characters.Firstly the 6 rbcL sequences and some rbcL sequences of these families from Genbank were aligned using Clustal W version 1.7. Then using PAUP 4.0 10b software, Elymus trachycaulus and Pseudoroegneria spicata (Poaceae) and Carex nigra (Cyperaceae) as outgroups respectively, 3 striction consensus trees were constructed.The phylogenetic trees supported that Eriocaulaceae be treated as Eriocaulales because this family always been a nature independent group connected with other families. Eriocaulaceae grouped with Commelinaceae, which supported the close relationship and parallel evolution between the two families. Juncaceae was not close to Eriocaulaceae and more primitive. The relationship between Juncaceae and Cyperaceae was closer than that between Juncaceae and Poaceae. Among these families, Poaceae was the most primitive family and far from Eriocaulaceae. Also in Eriocaulaceae, Eriocaulon was supported to be more primitive.