Teosinte ligule allele narrows plant architecture and enhances high-density maize yields.

Abstract

Increased planting densities have boosted maize yields. Upright plant architecture facilitates dense planting. Here, we cloned <i>UPA1</i> (<i>Upright Plant Architecture1</i>) and <i>UPA2</i>, two quantitative trait loci conferring upright plant architecture. <i>UPA2</i> is controlled by a two-base sequence polymorphism regulating the expression of a B3-domain transcription factor (<i>ZmRAVL1</i>) located 9.5 kilobases downstream. <i>UPA2</i> exhibits differential binding by DRL1 (DROOPING LEAF1), and DRL1 physically interacts with LG1 (LIGULELESS1) and represses LG1 activation of <i>ZmRAVL1</i> <i>ZmRAVL1</i> regulates <i>brd1</i> (<i>brassinosteroid C-6 oxidase1</i>), which underlies <i>UPA1</i>, altering endogenous brassinosteroid content and leaf angle. The <i>UPA2</i> allele that reduces leaf angle originated from teosinte, the wild ancestor of maize, and has been lost during maize domestication. Introgressing the wild <i>UPA2</i> allele into modern hybrids and editing <i>ZmRAVL1</i> enhance high-density maize yields.