Signaling from maize organ primordia via FASCIATED EAR3 regulates stem cell proliferation and yield traits

David Jackson and colleagues identify FEA3, encoding an LRR-receptor-like protein in maize, which responds to signals from organ primordia to the stem cell niche to regulate stem cell proliferation, a function that is conserved in Arabidopsis. They find that weak alleles of fea3 enhance hybrid maize yield traits. Shoot apical meristems are stem cell niches that balance proliferation with the incorporation of daughter cells into organ primordia. This balance is maintained by CLAVATA–WUSCHEL feedback signaling between the stem cells at the tip of the meristem and the underlying organizing center. Signals that provide feedback from organ primordia to control the stem cell niche in plants have also been hypothesized, but their identities are unknown. Here we report FASCIATED EAR3 (FEA3), a leucine-rich-repeat receptor that functions in stem cell control and responds to a CLAVATA3/ESR-related (CLE) peptide expressed in organ primordia. We modeled our results to propose a regulatory system that transmits signals from differentiating cells in organ primordia back to the stem cell niche and that appears to function broadly in the plant kingdom. Furthermore, we demonstrate an application of this new signaling feedback, by showing that weak alleles of fea3 enhance hybrid maize yield traits.