A natural ZmDGK4 allele accelerates maize grain dehydration via ER-localized phosphatidic acid signaling

Here, we fine-map the major quantitative trait locus, qGWC2, and identify its causal gene, ZmDGK4, which encodes an endoplasmic reticulum (ER)-localized diacylglycerol kinase. ZmDGK4 drives the production of unsaturated phosphatidic acid (PA), establishing a lipid-mediated developmental checkpoint that coordinates grain maturation.

Notably, the favorable ZmDGK4 allele accelerates grain dehydration through a synergistic effect of elevated expression and an H593P substitution that enhances catalytic activity. Elevated ZmDGK4 activity primes ER proteostasis and sustains abscisic acid (ABA) signaling, thereby enabling a timely transition from grain filling to physical dehydration. In contrast, ZmDGK4 knockout delays this metabolic shift and results in elevated GWC.