Black soybean (Glycine max L.) has been used as a traditional medicine because its seed coat contains various natural phenolic compounds such as anthocyanins. The objective of this study was to reveal the genetic variation in the agricultural traits, phytochemicals, and antioxidant activity of 172 Korean black soybean landraces (KBSLs) and establish a relationship among them. The evaluation of three agricultural traits (days to 50% flowering, maturity, and 100-seed weight), six phytochemicals (delphinidin-3-glucoside, cyaniding-3-glucoside, petunidin-3-glucoside, daidzin, glycitin, and genestin), and four antioxidant activities (2,2-diphenyl-1-picrylhydrazyl (DPPH), 2,2′-azino-bis-(3-ethylbenzothiazoline-6-sulfonic acid)(ABTS), ferric-reducing antioxidant power (FRAP), and the total polyphenol content (TPC) of 172 KBSLs were analyzed in 2012 and 2015. The agricultural traits, phytochemicals, and antioxidant activities of the 172 KBSLs showed wide variation among the accessions and years. In correlation analysis, the agricultural traits and phytochemicals showed positive and negative correlations with phytochemicals and antioxidant activity, respectively. The principal component analyses result indicated that phytochemicals accounted for most of the variability in the KBSLs. In clustering analysis, the 172 KBSLs were classified into four clusters. These results could lead to expanding the knowledge of the agricultural traits, phytochemicals, and antioxidant activity of the KBSLs, which are valuable materials for the development of new soybean varieties.

Amaranthus species are widely used as grain and leaf vegetables around the world and are potential dietary sources of antioxidants and phenolic compounds. In this study, we examined the variation in total flavonoid contents, total polyphenol contents, and antioxidant activities among 120 accessions of nine Amaranthus species. The antioxidant activity of DPPH (2,2-diphenyl-1-picrylhydrazyl) of the 120 amaranth accessions ranged from 1.1 (A. tricolor) to 75.2 (A. tricolor mg ascorbic acid equivalents (AAE)/g in 2018, and 8.5 (A. tricolor) to 68.8 (A. dubius) mg AAE/g in 2019. ABTS (2,2′-azinobis (3-ethylbenzothiazoline 6-sulfonate)) antioxidant activity ranged from 16.7 (A. tricolor) to 78.3 (A. hypochondriacus) mg AAE/g in 2018, and 36.6 (A. tricolor) to 79.2 (A. dubius) mg AAE/g in 2019. Total flavonoid content (TFC) of 2018 and 2019 ranged from 21.7 (A. caudatus) to 52.7 (A. hybridus) and from 22.3 (A. viridis) to 54.7 (A. tricolor), respectively Antioxidant activities were compared using two methods and all components were measured in plants grown both in 2018 and 2019. We identified wide variation among the accessions and between plants grown in the two years. Antioxidant activities and phytochemical contents were consistently negatively correlated. The nine species and 120 accessions clustered into three groups according to their antioxidant activities, total flavonoid contents, and total polyphenol contents in each year. These results provide information about the nutritional profiles of different Amaranthus species.

Potato (Solanum tuberosum L.) is an important staple food and economic crop in many countries. It is of critical importance to understand the genetic diversity and population structure for effective collection, conservation, and utilization of potato germplasm. Thus, the objective of the present study was to investigate the genetic diversity and population structure of potato germplasm conserved in the National Agrobiodiversity Center (NAC) of South Korea to provide basic data for future preservation and breeding of potato genetic resources. A total of 24 simple sequence repeat (SSR) markers were used to assess the genetic diversity and population structure of 482 potato accessions. A total of 257 alleles were detected, with an average of 10.71 alleles per locus. Analysis of molecular variance showed that 97% of allelic diversity was attributed to individual accessions within the population, while only 3% was distributed among populations. Results of genetic structure analysis based on STRUCTURE and discriminant analysis of principal components revealed that 482 potato accessions could be divided into two main subpopulations. Accessions of subpopulation 1 mainly belonged to cultivars and breeding lines. Accessions of subpopulations 2 basically corresponded to wild relatives of potatoes. Results of this study provide useful information for potato improvement and conservation programs, although further studies are needed for a more accurate evaluation of genetic diversity and phenotypic traits of potatoes.

Sweet potato (Ipomoea batatas L. Lam) is an important food crop widely cultivated in the world. In this study, nine chloroplast simple sequence repeat (cpSSR) markers were used to analyze the genetic diversity and relationships of 558 sweet potato accessions in the germplasm collection of the National Agrobiodiversity Center (NAC). Eight of the nine cpSSR showed polymorphisms, while Ibcp31 did not. The number of alleles per locus ranged from two to four. In general, the Shannon index for each cpSSR ranged from 0.280 to 1.123 and the diversity indices and unbiased diversity ranged from 0.148 to 0.626, and 0.210 to 0.627, respectively. Results of the median-joining network showed 33 chlorotypes in 558 sweet potato accessions. In factor analysis, 558 sweet potato accessions were divided into four clusters, with clusters I and II composed only of the sweet potato accessions from Korea, Japan, Taiwan, and the USA. The results of this study confirmed that the genetic diversity of the female parents of sweet potato accessions conserved at the NAC is low and therefore more sweet potato accessions need to be collected. These results will help to establish an efficient management plan for sweet potato genetic germplasms at the NAC.

Ginseng (Panax ginseng C.A. Meyer), commonly known as Korean or Asian ginseng, is a perennial herb native to Korea and China. There has been limited research effort to analyze the genetic diversity and population structure of ginseng germplasm because of its growth habits. In the present study, genetic diversity and population structure of ginseng germplasm conserved in the National Agrobiodiversity Center (NAC) of South Korea were analyzed to provide basic data for future preservation and breeding of ginseng genetic resources. Seventeen simple sequence repeat (SSR) markers were used to assess the genetic diversity and population structure of 1109 ginseng accessions. Among 1109 ginseng accessions, 1042 (94.0%) accessions were landraces and 66 (6.0%) accessions were breeding lines (61 accessions, 5.5%) or cultivars (5 accessions, 0.5%). SSR markers revealed 56 different alleles with an average of 3.29 alleles per locus. The average gene diversity was 0.49. Analysis of molecular variance showed that 91% of allelic diversity was attributed to individual accessions within clusters while only 9% was distributed among clusters. Using discriminant analysis of principal components, 12 clusters were detected in 1109 ginseng accessions. The results of this study provide molecular evidence for the narrow genetic base of ginseng germplasm in NAC. For the broad understanding and efficient use of ginseng germplasm, it is necessary to analyze functional factors and to evaluate morphological traits.

Watermelon is an economically important vegetable fruit worldwide. The objective of this study was to conduct a genetic diversity of 68 watermelon accessions using single nucleotide polymorphisms (SNPs). Genotyping by sequencing (GBS) was used to discover SNPs and assess genetic diversity and population structure using STRUCTURE and discriminant analysis of principal components (DAPC) in watermelon accessions. Two groups of watermelons were used: 1) highly utilized 41 watermelon accessions at the National Agrobiodiversity Center (NAC) at the Rural Development Administration in South Korea; and 2) 27 Korean commercial watermelons. Results revealed the presence of four clusters within the populations differentiated principally based on seed companies. In addition, there was higher genetic differentiation among commercial watermelons of each company. It is hypothesized that the results obtained from this study would contribute towards the expansion of this crop as well as providing data about genetic diversity, which would be useful for the preservation of genetic resources or for future breeding programs.