Morphological and proteomic analysis of young spikes reveals new insights into the formation of multiple-pistil wheat

•The multiple-pistil wheat possesses 2–3 pistils in a floret without other floral organs defect.•The multiple-pistil wheat has obvious grain number advantage.•The secondary pistils are derived from extra stem cells that do not normally terminate activity in multiple-pistil wheat.•The DAPs were mainly involved in the translation and the metabolisms of carbohydrate, nucleotide and amino acid.•TaHUA2, TaRF2a, TaCHR12 and TaHEN2 may play vital roles in the regulation of wheat flower organ number.