Flo2 is considered to be a member of a conserved gene family in plants . TaFlo2-A1 is abundantly expressed in flag leaves and in developing grains at 5 DAF stage, and the expression level of the positive haplotype (TaFlo2-A1b) was higher than that of the negative haplotype (TaFlo2-A1a). The phenomenon of higher expression of the positive TaFlo2 haplotype is consistent with the results for rice OsFlo2, in which the overexpression of the positive haplotype significantly increases grain size . In rice, the flo2 mutation in the promoter and in the open reading frame hinders the expression of genes involved in the synthesis of starch and protein [27, 28]. In rice cultivars that have different genetic backgrounds, some flo2 mutations negatively affect grain quality attributes such as amylose content, grain appearance and physiochemical properties despite maintaining or increasing grain size [27, 28]. Based on these similarities between OsFlo2 and TaFlo2-A1 at the sequence, structure and expression levels, the 8-bp InDel mutation in the TaFlo2-A1 promoter likely regulates grain size by affecting the expression of genes involved in the synthesis of starch and protein in wheat grains. Therefore, the increased expression of TaFlo2-A1 has a positive effect on grain yield but may have a negative effect on some grain quality attributes in wheat, which shall need further investigations.