Studies Of Genetic Diversity And Genetic Integrity In Buckwheat Germplasm Resources

The buckwheat is a multipurpose plant which is belongs to the family Polygonaceae, Genus fagopyrum Mill.The buckwheat has two cultivated species, tartary buckwheat and common buckwheat.In this study, the genetic diversity of tartary buckwheat germplasm resources was assessed and the genetic integrity of common buckwheat germplasm resources regenerated with different methods was studied in order to obtain useful information for conservation and use of buckwheat genetic resources.This work analyzed the genetic diversity of 165 accessions of tartary buckwheat from 14 different geographical regions using 20 informative primer pairs of AFLP markers,and further obtained the helpful information for breeding and germplasm evaluation.Totally 938 loci were detected among which 314 (33.48%) were polymorphic.The number of amplified fragments and polymorphic fragments per primer combination were 46.9 and 15.7,respectively. Shannon's information index of different geographical groups was 0.1093-0.2661.The group from Sichuan possessed the highest level of genetic diversity, followed by those from Qinghai,Yunnan and Gansu/Ningxia;The group from Hunan was the lowest in genetic diversity. Five cluster groups were identified based on the dendrogram of pairwise Nei's genetic identity. The clustering results revealed that the genetic diversity of accessions of tartary buckwheat closely related to their origins. Five types of population structure within 165 tartary buckwheat accessions were inferred by Structure analysis,which also correlated to their geographic origins.The population structure of accessions from Yunnan and Sichuan provinces were the most complicated and multiplex.The result showed that the genetic relationship and diversity of tartary buckwheat populations correlated to their geographic distribution to a certain extent. Moreover, the current study supported that southwest in china is the original birthplace and the center of genetic diversity of cultivated tartary buckwheat. And we supported the spreading route from the origin of tartary buckwheat in China: Tibet in China-Bhutan-Nepal-Kashmir-Karakoram Hindukush route.Common buckwheat is a typical cross-pollinated species with the outcrossing rate of 100%.Maintaining the genetic integrity of germplasm resources during regeneration is an important subject for buckwheat multiplication. According to the method of pollination (insect and wind) and the reproductive biology of common buckwheat, spatial isolation, gauze net isolation and no isolation was designed for this reseach, with the genebank seeds as a control.In this study, we compared the impact of different isolation methods on genetic integrity changes in common buckwheat using morphological markers and molecular markers.The t-test was used to compare the agronomic traits of common buckwheat between the genebank seeds and their offsprings regenerated with different isolation methods. Genetic similarity index between the genebank seeds and their offsprings regenerated with different isolation methods was calculated based on the data of AFLP markers.The allele frequency and dendrogram comparison between the genebank seeds and their offsprings regenerated with different isolation methods was analyzed using SSR markers.The results indicated that the difference between genebank seeds and their offsprings was significant when isolation was not set during the regeneration of common buckwheat germplasm resources. Gauze net isolation could avoid pollen adulteration effectively. The offsprings regenerated by gauze net isolation possessed the highest level of genetic identity and genetic resemblance with the genebank seeds.For the spatial isolation, the internal distance more than 500 meters was the most effective.