Convergent selection of a WD40 protein that enhances grain yield in maize and rice

Abstract

A better understanding of the extent of convergent selection among crops could greatly improve breeding programs. We found that the quantitative trait locus <i>KRN2</i> in maize and its rice ortholog, <i>OsKRN2</i>, experienced convergent selection. These orthologs encode WD40 proteins and interact with a gene of unknown function, DUF1644, to negatively regulate grain number in both crops. Knockout of <i>KRN2</i> in maize or <i>OsKRN2</i> in rice increased grain yield by ~10% and ~8%, respectively, with no apparent trade-offs in other agronomic traits. Furthermore, genome-wide scans identified 490 pairs of orthologous genes that underwent convergent selection during maize and rice evolution, and these were enriched for two shared molecular pathways. <i>KRN2</i>, together with other convergently selected genes, provides an excellent target for future crop improvement.