A black soybean cultivar ‘Gyeongheukcheong’ was developed by Gyeongsangbuk-do Agricultural Research and Extension Services. ‘Gyeongheukcheong’ was selected from a cross between ‘RCS640’ and ‘Geomjeongsaeol’ in 2011. The cultivar was evaluated in multiple performance and yield trials in seven locations from 2017 to 2019. ‘Gyeongheukcheong’ has a gray pubescence, light brown pod, and dark green cotyledon, whereas ‘Cheongja 3’ has a brown pubescence, brown pod, and light green cotyledon. The seed weight and maturity of ‘Gyeongheukcheong’ was similar to that of ‘Chungja 3’. ‘Gyeongheukcheong’ was resistant to soybean mosaic virus (strain G6H), moderately resistant to bacterial pustule (caused by Xanthomonas axonopodis pv. glycines), and resistant to root rot. Total chlorophyll content (sum of chlorophyll a and b) in the green cotyledon of ‘Gyeongheukcheong’ was 48.0 μg/g, which was higher than that of ‘Cheongja 3’ (30.1 μg/g). The regional yield trial showed that ‘Gyeongheukcheong’ had a similar or significantly higher average yield than ‘Chungja 3’ in locations with single (similar) and double (19% higher) cropping systems, respectively. ‘Gyeongheukcheong’ represents a consumer-friendly black soybean with dark green cotyledons and high yield potential (Registration No. 9065).

A black soybean cultivar, “Saebaram” with green cotyledons, was developed and released by the Gyeongsangbuk-do Agricultural Research and Extension Services (GBARS) in 2019. It was developed from a single cross between “Seonheuk” and “RCS640” in 2011. The preliminary yield trial and advanced yield trial were conducted at GBARS from 2015 to 2016. The regional yield trial (RYT) was conducted in seven locations from 2017 to 2019 in Korea. “Saebaram” had purple flowers, grey pubescence, light brown pods, a black seed coat, an ellipse seed shape, and a large seed size (42.8 g/100 seeds). The seed size was significantly larger than that of the check cultivar “Cheongja 3” (36.2 g/100 seeds). Moreover, it was moderately resistant to bacterial pustule (caused by Xanthomonas axonopodis pv. glycines) and soybean mosaic virus (strain G6H). “Saebaram” had dark green cotyledons, whereas “Cheongja 3” had light green cotyledons. The total chlorophyll contents (chlorophyll a and chlorophyll b) in the green cotyledons of “Saebaram” and “Cheongja 3” were 76.1 μg/g and 30.1 μg/g, respectively. Furthermore, the RYT showed that “Saebaram” had 287 kg/10a, which was 10% higher than that of “Cheongja 3” (261 kg/10a). This black soybean cultivar with improved yield, large-size seeds, and dark green cotyledons is expected to have a high commercial value for Korean farmers (Registration No. 9155).

Understanding plant morphological and seed characteristics is an essential step for the utilization of genetic resources to improve targeted traits in soybean breeding programs. The purpose of this study was to evaluate the agronomic traits and seed pigments of 469 black soybean germplasms with green cotyledons to identify useful resources using multivariate analyses, correlation, principal component analysis (PCA), and cluster analyses. The results showed that the range of flowering days from planting were 37.7-71.5 days, harvesting days from planting were 112.3-153.0 days, plant height was 49.6-151.6 cm, and 100-seed weight was 9.1-49.3 g. According to the correlation analyses with agronomic traits, flowering and harvesting days were positively correlated with the plant height, number of nodes, and number of branches. Additionally, it was found that the chlorophyll a and total chlorophyll content had the greatest effect on the green color of the cotyledon. Based on the PCA, 13 quantitative traits were compressed into three components. The first three principal components accounted for 82.5% of the total variance. In this study, black soybean germplasms with green cotyledons were divided into four clusters by the K-means cluster analysis (non-hierarchical procedure), based on the PCA. The cluster analysis showed that chlorophyll a and plant height had a significant effect on the clustering of the black soybean germplasms used in this study. This study provides opportunities to easily select useful genetic resources for the development of new black soybean cultivars.

The soybean cultivar, ‘Saegeum’, has been developed for preparing soy-paste and tofu. The soybean cultivars ‘Daepung’ and ‘SS98207-3SSD-168’ were crossed in 2003 to obtain ‘Saegeum’. Single seed descent method was used to advance the generation from F₃ to F₅, and the plant lines with promising traits were selected from F₆ to F₇ by pedigree method. The preliminary yield (PYT) and advanced yield trials (AYT) were conducted from 2009 to 2010, and the regional yield trial (RYT) was conducted in 12 regions between 2011 and 2013. The morphological characteristics of ‘Saegeum’ were as follows: determinate plant type, white flower, tawny pubescence color, and brown pod color. Flowering and maturity dates were August 2, XXXX and October 17, XXXX, respectively. Plant height, first pod height, number of nodes, number of branches, and number of pods were 79 cm, 18 cm, 16, 2.3, and 44, respectively. The seed characteristics of ‘Saegeum’ were as follows: yellow spherical shape, yellow hilum, and the 100-seed weight was 25.4 g. ‘Saegeum’ was resistant to bacterial pustule and SMV in the field test, and its lodging resistance was mildly strong, whereas its shattering resistance was excellent. The ability of this cultivar to be processed into tofu, soybean malt, and other fermented products was comparable with that of ‘Daewonkong’. The yield of ‘Saegeum’ in the adaptable regions was 3.02 ton ha^-1. Thus, ‘Saegeum’ is adaptable to mechanized harvesting because of its high first pod height, as well as lodging and shattering resistance. (Registration number: 5929)

High-density genetic linkage mapping is critical for undertaking marker-assisted selection and confirming quantitative trait loci, as well as helping to build pseudomolecules of genomes. We constructed a genetic map using 94 F₁ populations generated from the interspecific cross between Korean cultivar “Wonwhang” (Pyrus pyrifolia, NCBI BioSample SAMN05196235) and European cultivar “Bartlett” (Pyrus communis). We designed a total of 24,267 SSR markers based on the genome sequences of “Wonwhang” for this. To select the markers that are linked to the traits important in pear breeding programs, SSR-containing genomic sequences were subjected to nucleotide sequence homology searches, which resulted in 510 SSR markers with high similarity to genes encoding proteins with putative functions such as transcription factors, resistance proteins, flowering time, and regulatory genes. Of these, 70 markers showed polymorphisms in parents and segregating populations and were used to construct a genetic linkage map, together with the unpublished 579 SNPs obtained from genotyping by sequencing analysis. The genetic linkage map covered 3,784.2 cM and the average distance between adjacent markers was 5.8 cM. Seventy SSR markers were distributed across 17 chromosomes with more than one locus.