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

Peter Digennaro,Ji Hyung Jun,Etienne Grienenberger,Thai Q Dao,Jennifer C Fletcher

doi:10.1002/pld3.103

Peter Digennaro, Ji Hyung Jun + Show 3 more

Open Access

https://doi.org/10.1002/pld3.103

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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.

Highlights

Plants are unique in their ability to generate new organs and tissues throughout their life span, producing intricate structures such as flowers and leaves via complex molecular regulatory mechanisms (Bar & Ori, 2014; Tsukaya, 2013)
Given the overlap in expression patterns between these genes, we examined whether CLE5 and/or CLE6 transcription was regulated by BOP or ASYMMETRIC LEAVES2 (AS2) gene activity in developing rosette leaf primordia using RT‐qPCR
Vegetative development is a highly coordinated series of events that starts with a primordium initiated from the shoot apical meristem

Summary

| INTRODUCTION

Plants are unique in their ability to generate new organs and tissues throughout their life span, producing intricate structures such as flowers and leaves via complex molecular regulatory mechanisms (Bar & Ori, 2014; Tsukaya, 2013). Expression of the founding Arabidopsis WOX gene family member, WUSCHEL (WUS), is limited by CLV3 signaling to the most central region of the shoot apical meristem (Laux, Mayer, Berger, & Jurgens, 1996), where it functions in a non‐cell‐autonomous manner to maintain stem cell activity in the overlying cells (Brand, Grunewald, Hobe, & Simon, 2002; Schoof et al, 2000; Yadav et al, 2011). GA promotes CLE6 expression in the root stele, and CLE6 over‐expression can partly suppress the phenotypes of GA‐deficient plants (Bidadi et al, 2014) Based on such observations it has been proposed that CLE peptides may play general roles in controlling stem cell fate via their communication with plant hormone‐regulated signaling networks (Whitford et al, 2008). Our studies indicate that CLE5 and CLE6 act downstream of leaf patterning factors and phytohormones to direct formation of the final leaf morphology

| EXPERIMENTAL PROCEDURES

| RESULTS

Findings

| DISCUSSION