Ethnobotany, evolution, and chemistry of medicinal bryophytes: Examples from the moss genus Plagiomnium.

摘要

The ethnobotany of bryophytes has been understudied because it is generally assumed that bryophytes never play a direct role in human life. Although there are fewer ethnobotanical uses of bryophytes than vascular plants, it is clear that these little plants do have ethnobotanical importance in different cultures around the world. This dissertation gives a cross-cultural overview of the traditional uses and classification of bryophytes, and focuses on the biology and chemistry of one particular genus with ethnobryological importance. 136 species of bryophytes are used around the world for a variety of purposes; about half of these are used for their medicinal properties. The majority of bryophyte uses are reported from Traditional Chinese Medicine and from Native American groups in Canada and the United States. Plagiomnium is a moss genus that has been used by the Oweekeno and Bella Coola First Nations in Canada to treat infections and swelling, and has also been used by practitioners of Traditional Chinese Medicine. In this study, the phylogeny and phytochemistry of Plagiomnium were examined in order to understand the evolution and function of putatively bioactive chemicals in this genus. The phylogeny reveals that Plagiomnium is paraphyletic, with the epiphytic genus Ruthenian nested within Plagiomnium Section Rostrata. Phylogenetic relationships of Plagiomnium are complicated by the presence of phylogenetic incongruence between different genomic compartments, which is a combined result of differences in rates of molecular evolution and the occurrence of hybridization. Flavonoids have been identified as the chemicals putatively responsible for the bioactivity of the medicinal species of Plagiomnium. Examination of flavonoids in the context of the phylogeny reveals that these chemicals are not strongly correlated with phylogenetic history, and may only be useful indicators of phylogenetic history at shallow taxonomic levels or for studies of hybridization. Correlations between flavonoid content and ecological factors in the context of the phylogeny challenge currently held hypotheses about the function of these chemicals. Previous authors have indicated that flavonoids play a role in protecting from elevated levels of UV light, but the results of this study indicate that flavonoids may serve multiple ecological functions in Plagiomnium.