Postdomestication selection of MKK3 shaped seed dormancy and end-use traits in barley

Anthropogenic selection of grain traits such as dormancy has shaped the developmental trajectories of crops. In cereals, shortening dormancy provides rapid and even postharvest germination, but increases the risk of weather-induced preharvest sprouting, with yearly harvest losses beyond 1 billion dollars. Our understanding of how, why, when, and where cereal dormancy diversification arose is fragmentary. Here, we show in the founder crop barley (<i>Hordeum vulgare</i>) that dormancy is primarily regulated through a mosaic of locus haplotypes comprising copy number variation and inherent kinase activity of <i>Mitogen-activated protein kinase kinase 3</i> (<i>MKK3</i>). We provide evidence supporting the historical selection of specific <i>MKK3</i> haplotypes that shaped dormancy levels according to changing climatic pressures and outline a genetic framework for breeders to balance grain dormancy and preharvest sprouting avoidance.