New alleles of the wheat domestication gene reveal multiple roles in growth and reproductive development.

The advantages of free threshing in wheat led to the selection of the domesticated allele, which is now present in almost all modern wheat varieties. and the pre-domestication allele, , encode an AP2 transcription factor, with the domesticated allele conferring a free-threshing character and a subcompact (i.e. partially compact) inflorescence (spike). We demonstrate that mutations in the miR172 binding site of the gene are sufficient to increase transcript levels via a reduction in miRNA-dependent degradation, consistent with the conclusion that a single nucleotide polymorphism in the miRNA binding site of relative to was essential in defining the modern allele. We describe novel gain- and loss-of-function alleles of and use these to define new roles for this gene in spike development. is required for the suppression of 'sham ramification', and increased Q expression can lead to the formation of ectopic florets and spikelets (specialized inflorescence branches that bear florets and grains), resulting in a deviation from the canonical spike and spikelet structures of domesticated wheat.