Buckwheat is a nutritional and economically crop belonging to Polygonaceae, Fagopyrum. To better understand the mutation patterns and evolution trend in the chloroplast (cp) genome of buckwheat, and found sufficient number of variable regions to explore the phylogenetic relationships of this genus, two complete cp genomes of buckwheat including Fagopyrum dibotrys (F. dibotrys) and Fagopyrum luojishanense (F. luojishanense) were sequenced, and other two Fagopyrum cp genomes were used for comparative analysis. After morphological analysis, the main difference among these buckwheat were height, leaf shape, seeds and flower type. F. luojishanense was distinguishable from the cultivated species easily. Although the F. dibotrys and two cultivated species has some similarity, they different in habit and component contents. The cp genome of F. dibotrys was 159,320 bp while the F. luojishanense was 159,265 bp. 48 and 61 SSRs were found in F. dibotrys and F. luojishanense respectively. Meanwhile, 10 highly variable regions among these buckwheat species were located precisely. The phylogenetic relationships among four Fagopyrum species based on complete cp genomes was showed. The results suggested that F. dibotrys is more closely related to Fagopyrum tataricum. These data provided valuable genetic information for Fagopyrum species identification, taxonomy, phylogenetic study and molecular breeding.

Tartary buckwheat tea (TBT) is the most popular and widely consumed buckwheat product in many countries. However, the perfect quality control standards for TBT were still lacking, and the content of heavy metals in TBT and their health risks to consumers were still unknown. In this research, the total phenolic content, total flavonoid content, and antioxidant capacity as well as six metal contents and their health risks in TBT were detected. The results showed that the total phenolic content, total flavonoid content, and antioxidant capacity varied significantly among different types of TBT. Meanwhile, six metal concentrations in TBT leaves and infusions decreased in the order of Zn, Cu, Cr, Ni, Pb, and Cd. Health risk assessment indicated that the heavy metal intake only from TBT would not cause a noncarcinogenic risk to consumers. However, a strong carcinogenic risk of Cr in TBT for consumers should be paid more attention.

Buckwheat is an important functional food material with high nutritional value. However, it is still a difficult task for the taxonomy studies of wild buckwheat that are only based on morphology. In order to demonstrate the most efficient DNA barcode in the phylogenetic research of buckwheat, promote the investigation of wild buckwheat, and also reveal the phylogenetic relationship between Fagopyrum species, psbE-psbL and ndhA intron were validated here, which previously have been proved to be promising DNA barcode candidates for phylogenetic studies in genera Fagopyrum. Meanwhile, ndhA intron + psbE-psbL and matK + psbE-psbL could distinguish the relationship between species clearly. Combining the results of morphology and molecular markers, we suggested the buckwheat species should be divided into two subgroups, one subgroup consisted of F. tataricum, F. esculentum, F. cymosum and its related wild species, and the other subgroup included other wild buckwheat species. Our results could fulfill molecular markers of taxonomy research in genera Fagopyrum, promote wild buckwheat species identification, and assist in the use of wild buckwheat resources in the future. Additionally, the phylogenetic relationship revealed here could provide valuable information for molecular breeding of buckwheat and provide reference for inter-species hybridization.