Comprehensive characterization of yam tuber nutrition and medicinal quality of Dioscorea opposita and D.alata from different geographic groups in China

China is an important domestication center of yams,and two main yam species of Dioscorea opposita and D.alata are commonly cultivated in China.However,the differences of nutritional and medicinal characteristics between the two species and their subgroups remain unclear,which would greatly affect the resource conservation and commercial utilization of yams.In this study,typical yam resources including the species of D.opposita(wild and cultivated Ruichang yam from southern China,and Tiegun yam from northern China)and two landraces of D.alata(Longyan yam and Anyuan yam from southern China)were selected as materials.Nutritional traits and medicinal characteristics were determined and analyzed respectively.The results showed that there was no significant differences in the content of most nutrients between D.opposita and D.alata,but most cultivated Ruichang yam of D.opposita showed higher levels of starch,soluble sugar,sucrose,and ascorbate in tuber than that in yam from D.alata.Moreover,an UPLC-MS method was developed for identification and determination of medicinal characteristics in the two species.The results showed that allantoin can be detected in all selected samples.Cultivated Ruichang yam of D.opposita possessed the highest allantoin content among the tested materials,and was significantly different with that in Tiegun yam and D.alata.Dioscin was not detected in D.alata.Overall,there was little difference in nutritional composition between D.opposita and D.alata,but the medicinal quality of D.opposita was better than that of D.alata.Due to the outstanding comprehensive quality,the local variety of cultivated Ruichang yam can be further developed and utilized.

Association Analysis for Quality Traits in a Diverse Panel of Chinese Sesame(Sesamum indicum L.)Germplasm

The main objective of this study was to evaluate the potential of a sesame （Sesamum indicum L.） panel for association analysis, and investigate the genetic basis of oil content （OC）, protein content, oleic acid concentration, and linoleic acid concentration using association mapping. A panel of 216 sesame accessions was phenotyped in a multi-environment trial and fingerprinted with 608 polymorphic loci produced by 79 primers, including simple sequence repeats （SSRs）, sequence-related amplified polymorphisms （SRAPs）, and amplified fragment length polymorphisms （AFLPs）. Population structure analysis revealed two subgroups in the population. The Q model performed better for its ability to re-identify associations for the four traits at highly significant P-values compared to the other three mixed models. And a total of 35 and 25 associations for the four traits in 2010 and 2011 were identified, respectively, with the Q model after Bonferroni correction. Among those associations, only one for OC was re-identified in two environments, and several markers associated simultaneously with multiple traits were discovered. These results suggest the power and stability of the Q model for association analysis of nutritional traits in this sesame panel for its slight population stratification and familial relationship, which could aid in dissecting complex traits, and could help to develop strategies for improving nutritional quality.