## 4 Discussion
Korea has its own wild soybean types, but other types of resources have also been introduced from both China and Japan, resulting in accessions with high genetic diversity. [PERSON] et al. (2019) analyzed 23 developed soybean and native varieties and 17 wild types using 40 SSR markers, and detected that the high genetic diversity of wild types was due to the loss of many alleles in the evolutionary process. The genetic distance between all pairings of groups by release period shows that those in the 1990s and 2000 onward were the closest (0.1909), and 2000 onward and before or during the 1980s were the farthest (0.5587 and 0.5731, respectively; Table 7). The PIC value, in terms of release periods among Korean soybean varieties, was the highest in those developed from 2000 onward (Table 6). The reason for this finding is that, since the mid-1980s, various varieties have been developed with the aim of diversification of use and high quality. Many varieties have been developed for comparison to other groups by release period. We also found that the most genetic diversity among varieties can be observed in those developed since the 2000s (Figure 1 and Figure S1, Table 4). This trend is expected to continue in the future. Many results of genetic diversity analyses and discrimination of varietal studies using DNA markers have been reported. [PERSON] et al. (2019) discriminated 82 of the 91 developed soybean varieties from 1913 to 2002 using five SSR markers--Sat_043, Sat_022, Sat_036, Sat_088, and Satt045--and reported that unidentified varieties could not be distinguished using their morphological characteristics. [PERSON] et al. (2019) reported that 18 sequence-tagged sites--cleaved amplification polymorphic sequence (STS-CAPS) markers (51 combinations)--were developed from base sequence information in prepared genomic DNA libraries, and 106 Korean soybean varieties were discriminated in 14 steps. [PERSON] et al. (2019) discriminated 83 soybean varieties using nine markers with high polymorphism and high diversity within the population. An allele of each marker was coded to form a nine-digit identification (ID) for the discrimination of soybean varieties. In Korea, the first developed soybean variety was Jangdanbaekmok produced by separating landrace through pure line isolation in 1913, and the first hybrid variety was developed in 1969 characterized with high yielding ability and resistant to mosaic virus (Korea, 2014). Until 2014, a total of 178 soybean varieties have been developed and registered at the two national institutes, the RDA-Genebank Information Center and the Korea Seed & Variety Service (Korea, 2014; Korea, 2014). [PERSON] et al. (2014) analysis that a total of four pedigrees involving 168 varieties (94.4% out of 178 varieties), which form the broadest network of pedigrees. We analyzed genetic diversity using 172 Korean soybean varieties developed until 2013. Of these, 162 varieties include in four pedigrees, the results of genetic diversity and pedigrees provide information for selection of parental lines and design of crossing strategies. The full-length sequence of the American soybean variety Willams 82 has been analyzed and published for the first time (Korea, 2014) and, using the sequence information, a large amount of information regarding candidate polymorphic SSR markers has also been published (Korea, 2014). In Korea, [PERSON] et al. (2019) analyzed the full-length sequences of six Korean soybean varieties to distinguish genomes from dense variation blocks (dVBs) with SNP accumulation and sparse variation blocks with little SNPs. As dVBs have distinctive characteristics according to variety, various differences were indeed found to exist among the varieties. Therefore, 202 dVB-specific insertion/deletion (indel) markers have been developed (Korea, 2014). A barcode system was established, which clearly distinguishes 147 Korean soybean varieties and is regularly updated whenever new varieties are developed (Korea, 2014; Korea, 2014).