Analysis Of Phylogenetic Relationships Of Fagopyum Mill

Buckwheat is an ancient dicotyledonous crop belonging to Fagopyrum Mill.(Polygo--naceae). According to researches, we know that there are rich buckwheat resources in China, especially in Sichuan, Yunnan and Guizhou Provinces.Up to now,26species have been illustrated, including two cultivated buckwheat, common buckwheat and tartary buckwheat. In this study, phylogenetic relationships among the14species were investigated using three DNA sequence data sets derived from matK, psbA-trnH of chloroplast DNA, and the internal transcribed spacer (ITS) region of18S-26S nuclear ribosomal DNA to examine relationships in14buckwheat species.The main study results were summarized as follows:1. Sequences features of ITS, matK and psbA-trnH:the ITS2region was highly variable as ITS1, whose variation degree was much higher than ITS2, whereas5.8S rDNA located in the hyperconservative region. There were much more variable sites and information sites in ITS and psbA-trnH than matK regions. These phylogenetic informa--tion sites made a significant contribution to the phylogenetic studies of buckwheat plants.2. All the topology analyses supported the buckwheat genus clustered together as a monophyletic group based on ITS, matK and psbA-trnH data set.3. The strict consensus tree of the combined sequences of ITS, matK and psbA-trnH divided14kinds of buckwheats clearly and stably into two branches, F.hailuogou was clustered alone at the base of the branch, and the rest of all were clustered together, which divided into two branches, clade Ⅰ and Ⅱ. The clade I included F.esculentum, F.tataricum, F.cymosum, F.wenchuanense, F.urophyllum and F.gracilips var. odontopterum R, in which F.urophyllum and F.gracilipes var. odontopterum R were more primitive species than F.cymosum and F.wenchuanense. The clade Ⅱ included F.qiangcai, F.pugense, F.gracilipes, F.cripatofolium, F.gracilipes var. odontopterum W, F.lineare, F. leptopodum var. grossi, in which F.qiangcai and F.pugense were more evolved than F.gracilipes, F.cripatofolium and F.gracilipes var. odontopterum W.4. Genetic relationships between buckwheat species:F.cymosum had much more closer relationship with F.tataricum than F.esculentum. There were very close relationship between F.cymosum and F.wenchuanense, which probably was a subspecies of F.cymosum. F.gracilipes var. odontopterum R and F.gracilipes had a significantly different evolutionary lines with each other, which could be more primitive species than F.gracilipes and F.gracilipes var. odontopterum W and even might be transitional species between cultivat- -ed species and wild species; F.gracilipes had close relationship with F.gracilipes var. odontopterum W, as a variety of F.gracilipes. F.qiangcai, Flineare and F. leptopodum var. grossi had close relationships between them. Different sequence analysis showed that the different location of the system show the particularity of evolutionary status of F.urophyllum.5. All phylogenetic studies showed that F.hailuogou had distant relationship with the rest of them and might be the most primitive species, which likely had its own unique evolutionary path.According to its molecular evidence and significant morphological differences, we confirmed F.hailuogou to be a new species of Fagopyrum Mill and recom--mended naming it to be Fagopyrum hailuogou J. R. Shao&Y. Tang.