A natural variation in the promoter of TaGDSL-7D contributes to grain weight and yield in wheat.

Grain weight (GW) is a critical agronomic trait that greatly impacts wheat yield, yet the underlying genetic factors remain largely unknown. Here, we identify and characterize a candidate gene TaGDSL-7D controlling GW in wheat through map-based cloning, which encodes an ER-located GDSL-family protein. Natural variations within the promoter of the GW-enhancing TaGDSL-7D(HS2) allele result in a differential transcriptional response by promoting the binding of the TaGT1 transcription factor, a positive GW regulator. Additionally, TaGT1 directly interacts with TaBZR1 to enhance TaGDSL-7D activation. Haplotype analysis revealed that TaGDSL-7D(HS2) is a superior haplotype, improving both GW and yield. Taken together, these findings highlight the pivotal role of TaGDSL-7D in deciphering the genetic basis of GW in wheat and provide valuable natural allelic variation for GW improvement in high-yield breeding programmes.