An Investigation Of Phylogenetic Diversity And Habitat Effect On The Wild Fagopyrum Species In Hengduan Mountain

Southwest China is the center of origin and distribution of Fagopyrum Mill, where about two-thirds of Fagopyrum species in the world were reported. During the protection and exploitation of wild-type buckwheat’s germplasm resource, we found many transition species which morphologically similar with the two wild species, especially in the LuojiMountain and LongzhouMountain. What contribute to this situation, genetic mutation or ecological environment? To investigate this issue, we combine morphological and molecular biological methods, such as DNA boarding technology, to analyze the genetic diversity and habitats of wild buckwheat in LuojiMountain and LongzhouMountain. The results were as follows:1. Distribution of wild buckwheat species:Five wild buckwheat species (F. cymosum, F. gracilipes, F. pugense, F. gracilipes var. odontopterum W, F. gracilipes var. odontopterum R) and five transition groups (Ⅰ, Ⅱ, Ⅲ, Ⅳ, Ⅴ) between F. pugense and F. gracilipes, were found in LongzhouMountain around elevation 1800-2300 m. At elevation of 2100-2300 m, population density of F. gracilipes and transition groups (Ⅲ, Ⅳ, Ⅴ) is 5 and 3, respectively; at elevation of 1900-2100 m, population density of transition groups is 5, F. gracilipes, F. gracilipes var. odontopterum W, F. gracilipes var. odontopterum R and F. cymosum is 4; at elevation of 1800-1900 m, population density of F. pugense and transition groups (Ⅰ, Ⅱ) is 5 and 3, respectively. Six buckwheat species (F. cymosum, F. gracilipes, F. crispatofolium, F. pugense, F. gracilipes var. odontopterum W, F. gracilipes var. odontopterum R) and five transition type (Ⅰ, Ⅱ, Ⅲ,Ⅳ, Ⅴ) between F. pugense and F. gracilipes were found in Luoji Mountain, which vertical elevation in about 1500-2100 m. In the elevation region of 1900-2100 m, population density of F. gracilipes is 5; in the elevation region of 1700-1900 m, population density of F. pugense is 5, F. gracilipes, F. gracilipes var. odontopterum W, F. gracilipes var. odontopterum R and transition type (Ⅳ, Ⅴ) is 3; in the elevation region of 1500-1700 m, population density of F. pugense, transition type (Ⅰ, Ⅱ, Ⅲ) is 5.2. During the resources investigation of LuojiMountain and LongzhouMountain, we found that with the increase of elevation, the dominant wild buckwheat species were changed. Low elevation areas, the dominant wild buckwheat species is mainly F. pugense and transitional type which similar to F. pugense; with the increase of elevation, F. gracilipes and transitional type which similar to F. gracilipes were dominant. It suggested that five transitional types between F. gracilipes and F. pugense have the evolution tendency from F. pugense and F. gracilipes, due to the choice of environmental (elevation), showing the inconsistency of the evolution speed.3. Inferred from sequence characteristicsand phylogenetic trees constructedbased on, the nuclear genome ITS of buckwheat species in the Longzhou Mountain, two branches were found:F. cymosum was one branch, the remaining wild buckwheat were into a large branch. And two subgroups were found in this branch:transition type Ⅰ and F. pugense clustered into onesubgroup, transitional type Ⅱ, Ⅲ, Ⅳ, Ⅴand F. gracilipes clustered into the other subgroup. The same analysis was performed during 11 buckwheat species in the LuojiMountain.We found that F. cymosum clustered into a single branch, the rest wild buckwheatwereinto a large branch. And two subgroups were found in this branch: transition type Ⅰ, Ⅱ, Ⅲ and F. pugense clustered into onesubgroup, transitional type Ⅳ, Ⅴ and F. gracilipes clustered into the other subgroup. These findings support the conclusion that the evolution tendency of wild buckwheat in closed environment (LuojiMountain and LongzhouMountain)has a certain bias, and natural selection pressures have produced a change at the genetic level.4. By analyzingresource distribution and evolution law of wild buckwheat in the environment of the middle of Hengduan Mountain,we found that the relatively closed habitat can also cause the evolution of species, and large amounts of transitional type will produce in the evolutionary process, while with theevolution, the genetic diversity of wild buckwheat will tendto be simplified, eventually.