A stepwise route to domesticate rice by controlling seed shattering and panicle shape.

Asian rice ( L.) is consumed by more than half of the world's population. Despite its global importance, the process of early rice domestication remains unclear. During domestication, wild rice ( Griff.) acquired non-seed-shattering behavior, allowing humans to increase grain yield. Previous studies argued that a reduction in seed shattering triggered by the mutation led to increased yield during rice domestication, but our experiments using wild introgression lines show that the domesticated allele alone is insufficient for shattering loss in . . The interruption of abscission layer formation requires both and mutations, demonstrating that the selection of shattering loss in wild rice was not as simple as previously suggested. Here we identified a causal single-nucleotide polymorphism at within the seed-shattering gene , which is conserved in and subspecies but absent in the -aus group of rice. Through harvest experiments, we further demonstrated that seed shattering alone did not significantly impact yield; rather, yield increases were observed with closed panicle formation controlled by and further augmented by nonshattering, conferred by integration of and alleles. Complementary manipulation of panicle shape and seed shattering results in a mechanically stable panicle structure. We propose a stepwise route for the earliest phase of rice domestication, wherein selection of visible -controlled closed panicle morphology was instrumental in the sequential recruitment of and , which together led to the loss of shattering.