A rice QTL GS3.1 regulates grain size through metabolic-flux distribution between flavonoid and lignin metabolons without affecting stress tolerance

Zhang et al. report QTL GS3.1 as regulating rice grain size via metabolic flux allocation between two branches of phenylpropanoid metabolism. Their results identify the biosynthetic pathway for grain size regulation via a multidrug and toxic compounds extrusion transporter, and demonstrate enlarged grains, reduced flavonoid content, and increased lignin content in the panicles with GS3.1.