EXPANSIN A6 and GRAIN WIDTH 2 genes differentially affect grain weight, grain number, and yield of wheat through their physiological determinants.

Overexpression of EXPANSIN A6 in wheat increases grain weight and yields, while GRAIN WIDTH 2 knockout enhances grain weight but reduces overall yield in field conditions.

• Why it matters: Understanding the physiological mechanisms behind the trade-off between grain number and grain weight is crucial for improving wheat yield, especially under different planting densities.
• What they did: Researchers evaluated three wheat line groups—TaExpA6, TaGW2, and TaP1×GW2A—along with their wild types, in field experiments at conventional and low planting rates, measuring traits like grain weight, grain number, and yield.
• The result: TaExpA6 increased grain weight and was the only line to boost overall grain yield, while TaGW2 increased grain weight but reduced spike and grain number, highlighting the importance of grain-specific gene expression in mitigating trade-offs.