TaPDCD5 negatively regulates wheat grain size and weight by modulating ROS accumulation

Grain size and weight are key determinants of wheat yield, yet their genetic basis remains incompletely understood. In this study, we have identified TaPDCD5 , a wheat gene encoding a double-stranded DNA-binding domain protein, as a negative regulator of grain size and weight. Overexpression, knockout, and expression studies indicated that TaPDCD5 elevates H 2 O 2 levels by suppressing the expression of ROS-scavenging genes, thereby inhibiting grain development. Knockout of TaPDCD5 in the commercial cultivar Xinong 511 similarly increased grain size and weight, confirming its function across genetic backgrounds. A haplotype of TaPDCD5-1B associated with higher grain yield has undergone selection during modern breeding. Collectively, TaPDCD5 is a promising target for molecular breeding to improve wheat yield.