Soybean [Glycine max (L.) Merrill]: importance as a crop and pedigree reconstruction of Korean varieties.

Soybean [Glycine max (L.) Merrill] is one of the most important crops in the world and in Korea as well. Since the official start of soybean breeding program in Korea at which a landrace ‘Jangdanbaekmok’ was first released to promote cultivation in 1913, approximately one century has elapsed. Currently, a total of 178 soybean varieties are registered at two representative Korean national institutes, the RDA-Genebank Information Center (http://www.genebank.go.kr) and the Korea Seed & Variety Service (http://www.seed.go.kr). Of these, 155 varieties (87.1%) have been developed through hybridization-based breeding technologies, of which most cultivars (133 varieties, 85.8%) have been released in the last twenty five years. In this review, we attempted to integrate all the information for individual cultivars and to rebuild a breeding pedigree including the entirety of registered Korean soybean varieties. The analysis has resulted in a total of four pedigrees involving 168 cultivars (94.4% out of 178 cultivars), which form the broadest network of pedigrees. Each of pedigrees highlights different key varieties within the context of progenitor networks derived from crossing of various elite parental lines as follows; pedigree I-‘Kwangkyo’, ‘Hwangkeumkong’, ‘Paldalkong’ and ‘Sinpaldalkong2’, pedigree II-‘Baegunkong’, ‘Jangyeobkong’ and ‘Keunolkong’, pedigree III-‘Danyeob’, ‘Pangsa’ and ‘Eunhakong’. These pedigrees also reveal purpose (i.e., desirable traits)-driven development of characteristic soybean varieties during the past century of breeding history in Korea. We expect that the pedigree reconstructed in this study will provide breeders with information useful to design breeding schema and guidance towards the genomics-assisted soybean improvement in the future.