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Research Project: Developmental and Environmental Signaling Pathways Regulating Plant Architecture

Location: Plant Gene Expression Center

Title: Peptide signaling molecules CLE5 and CLE6 affect Arabidopsis leaf shape downstream of leaf patterning transcription factors and auxin

item DIGENNARO, P - University Of California
item GRIENENBERGER, ETIENNE - University Of California
item DAO, THAI - University Of California
item JUN, JI HYUNG - University Of North Texas
item Fletcher, Jennifer

Submitted to: Plant Direct
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/23/2018
Publication Date: 10/20/2018
Citation: DiGennaro, P., Grienenberger, E., Dao, T.Q., Jun, J., Fletcher, J.C. 2018. Peptide signaling molecules CLE5 and CLE6 affect Arabidopsis leaf shape downstream of leaf patterning transcription factors and auxin. Plant Direct. 2(12):1-14.

Interpretive Summary: Plants are unique in their ability to continually generate new organs such as leaves, which act as critical sites for photosynthesis, gas exchange and biomass accumulation. Yet despite their importance to plant growth, and therefore crop production, much remains to be understood about the genetic mechanisms that control leaf formation, shape and function. In this article we study the regulation and function of two members of the CLAVATA3/ EMBRYO SURROUNDING REGION-RELATED (CLE) family of small signaling molecules during Arabidopsis leaf development. We show that the closely related CLE5 and CLE6 genes are expressed only at the base of leaves and other plant organs, and that the amount of CLE5 and CLE6 expression is controlled by several upstream regulatory factors and by the plant hormone auxin. Mutational analysis reveals that CLE5 and CLE6 act in late steps of leaf development to direct the formation of the final leaf shape. Our results identify several new candidate genes for translational research to improve crop productivity in agriculturally important plant species.

Technical 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 CLAVATA3/ESR-RELATED peptide family, CLE5 and CLE6, which lie adjacent to each other on chromosome 2. Uniquely among the CLE genes, CLE5 and CLE6 are expressed specifically at the base of developing leaves and floral organs, adjacent to the boundary with the shoot apical meristem. During vegetative development CLE5 and CLE6 transcription is regulated by the leaf patterning transcription factors BLADE-ON-PETIOLE1 (BOP1) and ASYMMETRIC LEAVES2 (AS2), as well as by the WUSCHEL-RELATED HOMEOBOX (WOX) transcription factors WOX1 and PRESSED FLOWER (PRS). Moreover, CLE5 and CLE6 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 CLE5 and CLE6 independently and together have subtle effects on rosette leaf shape. Our study indicates that the CLE5 and CLE6 peptides function downstream of leaf patterning factors and phytohormones to modulate the final leaf morphology.