Peptide signaling molecules <scp>CLE</scp>5 and <scp>CLE</scp>6 affect Arabidopsis leaf shape downstream of leaf patterning transcription factors and auxin

Abstract

Abstract Intercellular signaling mediated by small peptides is critical to coordinate organ formation in animals, but whether extracellular polypeptides play similar roles in plants is unknown. Here we describe a role in Arabidopsis leaf development for two members of the CLAVATA 3/ ESR ‐ RELATED peptide family, CLE 5 and CLE 6, which lie adjacent to each other on chromosome 2. Uniquely among the CLE genes, CLE 5 and CLE 6 are expressed specifically at the base of developing leaves and floral organs, adjacent to the boundary with the shoot apical meristem. During vegetative development CLE 5 and CLE 6 transcription is regulated by the leaf patterning transcription factors BLADE ‐ ON ‐ PETIOLE 1 ( BOP 1) and ASYMMETRIC LEAVES 2 ( AS 2), as well as by the WUSCHEL ‐ RELATED HOMEOBOX ( WOX ) transcription factors WOX 1 and PRESSED FLOWER ( PRS ). Moreover, CLE 5 and CLE 6 transcript levels are differentially regulated in various genetic backgrounds by the phytohormone auxin. Analysis of loss‐of‐function mutations generated by genome engineering reveals that CLE 5 and CLE 6 independently and together have subtle effects on rosette leaf shape. Our study indicates that the CLE 5 and CLE 6 peptides function downstream of leaf patterning factors and phytohormones to modulate the final leaf morphology.