Abstract
Small secreted peptides are important players in plant development and stress response. Using a targeted in silico approach, we identified a family of 14 Arabidopsis genes encoding precursors of serine-rich endogenous peptides (PROSCOOP). Transcriptomic analyses revealed that one member of this family, PROSCOOP12, is involved in processes linked to biotic and oxidative stress as well as root growth. Plants defective in this gene were less susceptible to Erwinia amylovora infection and showed an enhanced root growth phenotype. In PROSCOOP12 we identified a conserved motif potentially coding for a small secreted peptide. Exogenous application of synthetic SCOOP12 peptide induces various defense responses in Arabidopsis. Our findings show that SCOOP12 has numerous properties of phytocytokines, activates the phospholipid signaling pathway, regulates reactive oxygen species response, and is perceived in a BAK1 co-receptor-dependent manner.
Highlights
In order to counter constant pathogen aggression, plants have developed sophisticated perception and defense systems.These plant responses are regulated by complex networks involving regulatory proteins and hormones, and are associated with massive changes in gene expression (Buscaill and Rivas, 2014)
The induction of numerous genes involved in the protection against oxidative stress such as peroxidases, glutathione transferase, and phenylpropanoid synthases in proscoop12 in response to E. amylovora infection (Supplementary Table S4) might indicate that its lack of expression could result in a decrease in H2O2 levels
It is known that antioxidant responses in roots decrease the H2O2 level in the elongation zone, thereby contributing to root growth (Dunant et al, 2007;Tsukagoshi et al, 2010).The constitutive expression of PROSCOOP12 in roots (Fig. 2) could contribute to higher levels of H2O2 and act as a moderator of root elongation under normal conditions
Summary
In order to counter constant pathogen aggression, plants have developed sophisticated perception and defense systems.These plant responses are regulated by complex networks involving regulatory proteins and hormones, and are associated with massive changes in gene expression (Buscaill and Rivas, 2014). It has been shown that small secreted peptides play an important role through their direct interaction with pathogens or through their function in development and cell–cell communication involving ligand– receptor interactions (Murphy et al, 2012; Marmiroli and Maestri, 2014; Gust et al, 2017).The secreted peptides derive from protein precursors having a shared N-terminal signal peptide which targets the protein to the secretory pathway They can be categorized into two major classes: (i) the small post-translationally modified peptides (PTMPs) which are the targets of post-translational maturation and are produced. A first induction of AtPep and other peptides of this family by wounding or pathogen attack has a positive feedback on the expression of its own precursors as well as defense marker genes, that is thought to amplify defense signaling pathways (Huffaker and Ryan, 2007)
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