Development of functional markers of wheat grain size related gene TaCYP78A17

Grain size is a crucial factor influencing wheat yield. To develop functional markers related to wheat grain size, we cloned a potential grain size-related gene, TaCYP78A17, and conducted systematic evolution, expression pattern, allelic variation, and functional marker development studies. The results revealed that TaCYP78A17 belongs to the wheat cytochrome P450 CYP78A family and is highly expressed in wheat spikes and grains. Six SNPs and two InDels were identified in the TaCYP78A17-Ap among thirty common wheat varieties. A functional marker, InDel-A17, was developed based on InDel 4 and InDel 8, classifying the thirty wheat varieties into three haplotypes: TaCYP78A17-Ap-HapI, TaCYP78A17-Ap-HapII, and TaCYP78A17-Ap-HapIII. This functional marker was validated in 323 wheat varieties, demonstrating its ability to effectively distinguish the three haplotypes. Phenotypic investigations indicated that wheat with the TaCYP78A17-Ap-HapI haplotype exhibited significantly higher thousand-grain weight and larger seed size compared to those with TaCYP78A17-Ap-HapII or TaCYP78A17-Ap-HapIII. These findings hold promise for the application of molecular marker-assisted selection in wheat breeding.