Elevation of soybean seed oil content through selection for seed coat shininess

Many leguminous species have adapted their seed coat with a layer of powdery bloom that contains hazardous allergens and makes the seeds less visible, offering duel protection against potential predators1. Nevertheless, a shiny seed surface without bloom is desirable for human consumption and health, and is targeted for selection under domestication. Here we show that seed coat bloom in wild soybeans is mainly controlled by Bloom1 (B1), which encodes a transmembrane transporter-like protein for biosynthesis of the bloom in pod endocarp. The transition from the 'bloom' to 'no-bloom' phenotypes is associated with artificial selection of a nucleotide mutation that naturally occurred in the coding region of B1 during soybean domestication. Interestingly, this mutation not only 'shined' the seed surface, but also elevated seed oil content in domesticated soybeans. Such an elevation of oil content in seeds appears to be achieved through b1-modulated upregulation of oil biosynthesis in pods. This study shows pleiotropy as a mechanism underlying the domestication syndrome(2), and may pave new strategies for development of soybean varieties with increased seed oil content and reduced seed dust.