Molecular Phylogenetics Of Batrachospermum Roth(Rhodophyta) Of China

The means of molecular biology, morphology, taxonomy, bioinformatics and statistics were used to determine the morphological character, flora, molecular systematic and phylogeny of Batrachospermum Roth in China. Morphological and floristics studies were made among30taxa of Batrachospermum in China. Multilocus molecular data from one nuclear gene (the ribosomal SSU), one chloroplast gene (rbcL), and two mitochondrial genes (COI, cox2-3spacer) were used to determine the phylogenetic placement of these taxa in Batrachospermum. Meanwhile, the studies on four endemic species and Batrachospermum arcuatum were also undertake to determine there phylogenetic relationship.The studies on taxonomy and flora of Batrachospermum in China were made. Morphological studies show that Batrachospermum arcuatum specimens for4streams were monoecious; while for3streams were dioecious. The descriptions of other taxa are accord with the previous report. Thirty species (including varieties) of Batrachospermum were reported in China, which distributed in20provinces. The analysis of flora shows that there are8areal types of Batrachospermum, among which the endemic to China is predominant, including15species and accounting for48.3%. The temperature distribution of Batrachospermum is obvious and the number of the species takes82.8%totally. Batrachospermum is rich in East China, Central China and Southwest China; and rare in Northwest China, North China and Northeast China. Endemic species are distributed mainly in East China.Multilocus molecular data were used to determine the phylogenetic relationship of taxa in genus Batrachospermum. The placement of the6taxa we collected in the phylogenetic trees was similar and the results accord with the morphological observation.The results based on rbcL sequence suggested that the placement of Thoreales was similar in each phylogenetic tree and formed a monophyletic group with high bootstrap support. Section Hybrida and section Contorta had a relatively small sequence divergence. The results of this work suggested combining section Hybrida as section Contorta. B. gelatinosum is the type of paraphyletic genus Batrachospermum. However, most of the species currently included in the section Batrachospermum are in a well-supported clade distant to B. gelatinosum. The same result was got with other sequence data. The results of phylogenetic relationship within Batrachospermum species based on SSU sequences showed that the taxonomic relationships of section Aristata, section Virescentia, section Turfosa and section Contorta had not been satisfactorily resolved. The results based on COI sequence showed that there was a good support for a clade of section Contorta species, which was apart from most Batrachospermum taxa. So we agreed with the proposal that taxa formerly in Batrachospermum sections Contorta and Hybrida were elevated into a new genus Kumanoa. The results based on cox2-3spacer sequence showed that Batrachospermum torsivum was sister to section Batrachospermum taxa, morphologically very distant entities. But only cox2-3spacer sequence of B. torsivum was got, and more sequence data were needed to solve this problem.Four endemic Batrachospermum species in China, B. hongdongense, B. longipedicellatum, B. curvatum and B. intortum, were analyzed with multilocus data in order to assess their phylogenetic placement. Multilocus molecular data from one nuclear gene (the ribosomal SSU), one chloroplast gene (rbcL), and two mitochondrial genes (COI, cox2-3spacer) as well as morphological study were used to determine the phylogenetic relationships of these endemic species within the Batrachospermales. B. hongdongense and B. longipedicellatum had previously been placed in Batrachospermum section Batrachospermum, but based on the data from this study should be transferred into section Helminthoidea. B. curvatum and B. intortum clearly belong to the newly established genus Kumanoa.Batrachospermum arcuatum specimens were analyzed from seven stream segments in North China. Morphological characteristics were observed and cluster analysis was used to evaluate the divergence among thalli from. Sequence data of the rbcL gene (chloroplast gene) and cox2-3spacer region (mitochondrial gene) were also utilized to evaluate genetic variation in specimens among stream segments. The specimens from four of the streams were monoecious, while the individuals at the other three locations were dioecious. Cluster analysis showed that the monoecious specimens were not separated from the dioecious specimens, based on morphology, but rather the specimens were grouped by geographical closeness and habitat similarity. Likewise, the combined analyses of rbcL and the cox2-3spacer data from provided more evidence that breeding system (monoecy vs. dioecy) is not a good morphological character to distinguish species.