Genetic Analysis of Genomic Locations Underlying Domestication Transitions in Soybean

Although many canonical domestication genes have been cloned from major grass crop species, domestication transitions in eudicot crop species including soybean have been poorly studied at the molecular level. In major crop species, cultivated species and their progenitors usually show distinct morphological and physiological differences in so-called domestication syndrome traits such as seed size, color, shattering, seed dormancy, flowering time, branching, and prostate growth habit. Soybean is not an exception. However, organs or tissues where several domestication traits are expressed differ between soybean and grasses. For example, shattering is related to pod in soybean but to pedicel in rice. In an analysis of high-depth resequencing genomes of Korean ten cultivated and six wild accessions, we reported soybean homologues of cloned canonical domestication genes as well as several examples, which are likely specific to soybean or eudicot crop plants, in the identified 206 candidate domestication regions. Currently, we are analyzing 19 cultivated and 19 wild soybeans that likely represent worldwide soybean populations. We use various methods including reduction of diversity, F_ST, site frequency spectrum, and genetic mapping of the domestication traits in a cultivated and wild cross population. The results show that the number (2,049) of candidate domestication genes were reduced to two thirds of that from the analysis of the previous small population. An effort is on-going to clone a strong candidate gene for a complementation test by transformation to validate our analysis results.