A single domestication origin of adzuki bean in Japan and the evolution of domestication genes

Adzuki is a central legume in East Asian culinary culture, yet its domestication origin remains debated. Using ~700 accessions across Asia, we show that the initial domestication happened three to five thousand years ago in central Japan during the Jomon period, followed by a range expansion into China and secondary hybridization with Chinese wild populations. We mapped, validated, and dated key genes associated with seed coat color evolution (<i>VaPAP1</i> for loss of mottled black and <i>VaANR1</i> for gain of red colors). The frequency increases of variants affecting key domestication syndrome substantially predated the wild-cultigen divergence. Together, our results resolve the conflict between genetic and archaeological evidence about adzuki origins and reconstruct the evolutionary trajectory of archaeobotanically unobservable traits, consistent with a role of early weak selection during domestication.