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 post-harvest germination, but increases the risk of weather-induced pre-harvest sprouting (PHS) with yearly harvest losses beyond 1 billion USD. Our understanding of how, why, when and where cereal dormancy diversification arose is fragmentary. Here, we show in the founder crop barley (Hordeum vulgare) that dormancy is primarily regulated through a mosaic of locus haplotypes comprising copy-number variation and inherent kinase activity of Mitogen-activated protein kinase kinase 3 (MKK3). We provide evidence supporting the historical selection of specific MKK3 haplotypes that shape dormancy levels according to changing climatic pressures and outline a genetic framework for breeders to balance grain dormancy and PHS-avoidance.