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.

Legume dehulling often removes anti-nutrients while improving nutritional quality. However, the process may reduce the levels of other health-promoting metabolites. This study investigated the effect of dehulling on major nutrients, bioactive metabolites, and antioxidant activities using 22 faba bean cultivars typically grown in different parts of the world. The faba bean cultivars differed significantly in all the parameters assessed. Crude fiber (CFC), dietary fiber (DFC), crude protein, and crude fat contents were in the ranges of 5.24–10.56, 16.17–25.15, 19.83–30.90, and 0.79–1.94% in the whole seeds and 0.96–1.59, 4.14–9.50, 22.47–36.61, and 1.13–2.07% in the dehulled seeds, respectively. Moreover, fatty acids including palmitic acid, stearic acid, oleic acid, linoleic acid, and linolenic acid, bioactive metabolites including total phenol (TPC), total saponin (TSC), and total tannin (TTC) contents, and antioxidant activities including ABTS^•+-scavenging activity, ferric antioxidant power (FRAP), and DPPH^•-scavenging activity also showed significant variations. Dehulling significantly reduced DFC (55.09–79.30%), CFC (69.61–87.52%), and TTC (1.70–66.99%) in all the faba bean cultivars while increasing total protein content (9.31–17.69%). Dehulling also increased the total fat content (3.02–48.13%) in all the cultivars except Giant Three Seeded, a Japanese cultivar, which showed a 12.62% decrease. In contrast, dehulling exhibited varying results on fatty acids, TPC, TSC, and antioxidant activities among the faba bean cultivars. Accordingly, three cultivars: Primus from Hungary, Levens Marschbohne from Germany, and Ascott from France, exhibited simultaneous increases in nutritional levels after dehulling. Domasna-2 from Macedonia, Abawi# 1 from Peru, Seville from the United Kingdom, and Large Mazandran from Iran, on the other hand, exhibited marked reductions in nutritional levels, functional metabolites, and antioxidant activities. In general, our findings indicated that dehulling reduces crude fiber, dietary fiber, and tannin levels while increasing protein and fat contents in faba beans. However, fatty acids, phenolic content, and antioxidant activity may not be equally affected by dehulling and, therefore, specific genotypes should be inspected.

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.

Tea (Camellia sinensis (L.) O. Kuntze) is cultivated in many developing Asian, African, and South American countries, and is the most widely consumed beverage in the world. It is of critical importance to understand the genetic diversity and population structure of tea germplasm for effective collection, conservation, and utilization. In this study, 410 tea accessions collected from South Korea were analyzed using 21 simple sequence repeat (SSR) markers. Among 410 tea accessions, 85.4% (350 accessions) were collected from Jeollanam-do. A total of 286 alleles were observed, and the genetic diversity and evenness were estimated to be on average 0.79 and 0.61, respectively, across all the tested samples. Using discriminant analysis of principal components, four clusters were detected in 410 tea accessions. Among them, cluster 1 showed a higher frequency of rare alleles (less than 1%). Using the calculation of the index of association and rbaD value, each cluster showed a clonal mode of reproduction. The result of analysis of molecular variance (AMOVA) showed that most of the variation observed was within populations (99%) rather than among populations (1%). The present study revealed the presence of lower diversity and simpler population structure in Korean tea germplasms. Consequently, more attention should be focused on collecting and conserving the new tea individuals to broaden genetic variation of new cultivars in future breeding of the tea plant.

This study examined the levels of major flavonoids, nutritional components, total secondary metabolite contents, and antioxidant activities in 136 mung bean accessions and statistically analyzed the effect of seed weight difference on each. Vitexin and isovitexin were detected in all the mung bean accessions, with isovitexin being in a higher concentration regardless of seed weight difference. The contents of total protein and total starch were in the ranges of 22.01–28.96 and 32.62–49.03 g/100 g, respectively. Five fatty acids were detected by GC–FID analysis in all mung bean accessions, with linoleic acid being the most dominant (37.96–50.71 g/100 g). Total saponin content (TSC), total phenol content (TPC), DPPH^• scavenging activity, ABTS^•+ scavenging activity, and ferric reducing antioxidant power (FRAP) showed more than five-fold differences. Analysis of variance supported by multivariate analysis demonstrated that seed weight difference had a significant effect on total starch, all individual fatty acids except for stearic acid and oleic acid, TSC, and all antioxidant activities except for ABTS^•+ scavenging activity. On the other hand, vitexin, isovitexin, total protein, total phenol, and total fatty acid contents remained unaffected by seed weight difference. Overall, this study showed the diversity of key flavonoids, nutritional components, total secondary metabolite contents, and antioxidant activities in mung bean genetic materials. Moreover, the study unveiled how seed weight affects the analyzed parameters in mung beans for the first time. These findings could maximize the use of mung beans in food industries and breeding programs as well as lead to more studies in metabolomics and genomics.

Adzuki beans are widely cultivated in East Asia and are one of the earliest domesticated crops. In order to gain a deeper understanding of the genetic diversity and domestication history of adzuki beans, we conducted Genotyping by Sequencing (GBS) analysis on 366 landraces originating from Korea, China, and Japan, resulting in 6586 single-nucleotide polymorphisms (SNPs). Population structure analysis divided these 366 landraces into three subpopulations. These three subpopulations exhibited distinctive distributions, suggesting that they underwent extended domestication processes in their respective regions of origin. Phenotypic variance analysis of the three subpopulations indicated that the Korean-domesticated subpopulation exhibited significantly higher 100-seed weights, the Japanese-domesticated subpopulation showed significantly higher numbers of grains per pod, and the Chinese-domesticated subpopulation displayed significantly higher numbers of pods per plant. We speculate that these differences in yield-related traits may be attributed to varying emphases placed by early breeders in these regions on the selection of traits related to yield. A large number of genes related to biotic/abiotic stress resistance and defense were found in most quantitative trait locus (QTL) for yield-related traits using genome-wide association studies (GWAS). Genomic sliding window analysis of Tajima’s D and a genetic differentiation coefficient (Fst) revealed distinct domestication selection signatures and genotype variations on these QTLs within each subpopulation. These findings indicate that each subpopulation would have been subjected to varied biotic/abiotic stress events in different origins, of which these stress events have caused balancing selection differences in the QTL of each subpopulation. In these balancing selections, plants tend to select genotypes with strong resistance under biotic/abiotic stress, but reduce the frequency of high-yield genotypes to varying degrees. These biotic/abiotic stressors impact crop yield and may even lead to selection purging, resulting in the loss of several high-yielding genotypes among landraces. However, this also fuels the flow of crop germplasms. Overall, balancing selection appears to have a more significant impact on the three yield-related traits compared to breeder-driven domestication selection. These findings are crucial for understanding the impact of domestication selection history on landraces and yield-related traits, aiding in the improvement of adzuki bean varieties.