The Green Revolution genes Rht-B1b and Rht-D1b encode truncated DELLA proteins that confer gibberellin (GA)-insensitive semi-dwarfism in wheat. Their roles in reducing plant height and enhancing lodging resistance are well established, but their pleiotropic effects on specific components of plant architecture require further genetic dissection. Here, we reveal a previously unrecognized role of Rht-D1b in regulating tiller angle, a key determinant of canopy architecture. Quantitative trait locus (QTL) mapping identified Rht-D1b as a major locus controlling tiller angle. Functional validation showed that Rht-D1b not only reduces plant height but also increases tiller angle and tiller number, thereby optimizing canopy structure for enhanced yield potential. Transcriptome profiling indicated that Rht-D1b modulates the expression of genes involved in auxin signaling and polar auxin transport. Broad-scale phenotyping across diverse wheat accessions demonstrated that both Rht-B1b and Rht-D1b significantly increase tiller angle and leaf area index, with double mutants exhibiting the strongest effects on tiller architecture. Notably, the frequency of Rht-B1b and Rht-D1b has risen in modern cultivars, coinciding with a historical trend toward wider tiller angle. Together, these findings establish a novel pleiotropic role for the Green Revolution genes, demonstrating that they not only reduce plant height but also coordinate tiller angle and tiller number to optimize canopy architecture, ultimately elevating yield in wheat.

Rice tiller angle, as a component of plant architecture, affects rice grain yield via plant density. However, the molecular mechanism underlying rice tiller angle remains elusive. We report that the key domestication gene PROSTRATE GROWTH 1 (PROG1) controls rice tiller angle by regulating shoot gravitropism and LAZY1 (LA1)-mediated asymmetric distribution of auxin. Acting as a transcriptional repressor, PROG1 negatively regulates the expression of LA1 in light-grown rice seedlings. Overexpression of LA1 partially rescued the larger tiller angle of the PROG1 complementation transgenic plant (prog1-D). Double-mutant analysis showed that PROG1 acts upstream of LA1 to regulate shoot gravitropism and tiller angle. Mutation of Suppressors of lazy1 (SOL1), encoding DWARF3 (D3) acting in the strigolactone signal pathway, suppressed the large tiller angle of prog1-D by rescuing the transcription of LA1. The discovery of a light-sensitive PROG1-LA1 transcription regulatory module controlling rice shoot gravitropism and tiller angle sheds light on the genetic control of rice tiller angle.