Soybean [Glycine max (L.) Merr.] is an excellent source of protein, oil, carbohydrates, and many other bioactive ingredients. However, its raw mature seeds also contain several antinutritional components. The newly developed soybean cultivar ‘Hayoung’ has large yellow seeds and a low stachyose content, and is free of lipoxygenase, Kunitz trypsin inhibitor (KTI), and 7S α’-subunit proteins. ‘Hayoung’ was selected from the population derived from a cross between the intermediate parent (F4-4) and the breeding line (15G1). It has purple flowers, tawny pubescence, a determinate growth habit, and light-yellow pods at maturity. The seed of the cultivar has a yellow hilum and yellow seed coat color. The dry weight seed protein and oil content were 37.9 and 16.0%, respectively. The stachyose content was 3.1 g/kg, which was much lower than 12.7 g/kg of the check cultivar, ‘Daewon’. ‘Hayoung’ has shown resistance to soybean necrosis, soybean mosaic virus, Cercospora leaf spot and blight, black root rot, pod and stem blight, and bacterial pustule. ‘Hayoung’ matured on 22 October with a plant height of 56 cm and a 100-seed weight of 32.3 g. The average yield of the cultivar was 3.12 (Ton/ha), based on regional yield trials in 2018 at four locations. ‘Hayoung’ has been registered as a soybean cultivar (registration number: 8625, registration date: June 08, 2021) by the Korea Seed & Variety Service, Republic of Korea.

Soybean cultivars with genetically low levels of stachyose enhance the utilization of soybean in food as well as feed uses. The
objective
of this research is to obtain the information on indirection selection of soybean lines with low stachyose content using DNA marker based on rs2 (rs2) gene. Two genetic populations were developed from the crosses of three parents (116-13 parent : low stachyose content, PI417227 and PI506903 parents: normal stachyose content). Twenty F₂ plants of RS2_genotype and twenty F₂ plants of rs2rs2 genotype from each populations were harvested. Content of stachyose was detected by HPLC. Stachyose contents (g/kg) of 116-13, PI417227, PI506903 parents were 3.7, 23.7, and 17.8, respectively. In population 1, stachyose content 20 F₂ plants with RS2_ genotype was 14.8 – 24.1 and stachyose content 20 F₂ plants with rs2rs2 genotype was 2.1 – 4.7. In population 2, stachyose content 20 F₂ plants with RS2_ genotype was 12.4 – 19.7 and stachyose content 20 F₂ plants with rs2rs2 genotype was 2.1 – 5.0. Mean difference between RS2_ genotype and rs2rs2 genotype in population 1 and 2 was highly significant. From this results, selection of genetic lines with low stachyose content by DNA marker based on RS2 (rs2) gene will be possible.