SCOOP12 peptide acts on ROS homeostasis to modulate cell division and elongation in Arabidopsis primary root
Résumé
Abstract Small secreted peptides have been described as key contributors to complex signalling networks that control plant development and stress responses. The Brassicaceae-specific PROSCOOP family encodes precursors of Serine riCh endOgenOus Peptides named SCOOPs. In Arabidopsis thaliana, SCOOP12 has been shown to promote defence response against pathogens and to be involved in root development. Here, we explore its role as a moderator of the primary root development. We show that the PROSCOOP12 null mutation leads to longer primary roots through the development of longer differentiated cells while PROSCOOP12 overexpression induces dramatic plant growth impairments. In comparison, the exogenous application of the synthetic SCOOP12 peptide shortens root through meristem size and cell length reductions. Moreover, superoxide anion (O2.-) and hydrogen peroxide (H2O2) productions in root tips vary according to SCOOP12 abundance. Then, by using ROS scavengers that suppress the proscoop12 phenotype, SCOOP12-root growth regulation could be associated with ROS metabolism. Furthermore, our results suggest that peroxidases act as potential SCOOP12 downstream targets to regulate H2O2 production, which in turn triggers cell wall modifications in root. Finally, a massive transcriptional reprogramming, including the induction of genes from numerous other pathways for ethylene, salicylic acid and glucosinolates biosynthesis, was observed, emphasizing its dual role in defense and development.
