Genetic mapping of Cgdef gene controlling accumulation of 7S globulin (beta-conglycinin) subunits in soybean seeds.

Soy protein consists of mainly 7S globulin (beta-conglycinin) and 11S globulin (glycinin). The 7S globulin exerts favorable and unfavorable effects on human nutrition, food processing, and human health. Therefore, it is important for the improvement of the soy protein to control the content of 7S globulin. A mutant line lacking the 7S globulin was induced by gamma-ray irradiation, and the deficiency is controlled by a single recessive gene, cgdef. The Cgdef gene, despite its potential for improvement of the soy protein, has not been assigned to a linkage group of a soybean genetic map. We crossed "Mo-shi-dou Gong 503" with plants homozygous or heterozygous for the Cgdef allele and screened an F2 mapping population that segregated with the cgdef allele to locate the Cgdef gene on a soybean genetic map. By linkage analysis, we assigned the Cgdef gene to chromosome 19 at the position between the Satt523 and Sat_388 simple sequence repeat (SSR) markers. Six SSR markers (Sat_134, Sat_405, Satt143, Satt398, Sat_195, and Satt694) and 2 amplified fragment length polymorphism markers identified previously were mapped at the same position of the Cgdef gene. These markers should enable to conduct map-based cloning of the Cgdef gene.