Family-wide evaluation of RALF peptides in Arabidopsis thaliana

Plant peptide hormones are important players controlling various aspects of plants’ lives. RAPID ALKALINIZATION FACTOR (RALF) peptides have recently emerged as important players in multiple physiological processes. Numerous studies on RALF peptides focused on broad phylogenetic analysis including multiple species. Thus, progress has been made in understanding the evolutionary processes that shaped this family. Nevertheless, to date, there is no comprehensive, family-wide functional study on RALF peptides. Here, we analysed the phylogeny and function of the proposed multigenic RALF peptide family in the model plant , ecotype Col-0. Our phylogenetic analysis reveals that two of the previously proposed RALF peptides are not genuine RALF peptides, which leads us to propose a new consensus RALF peptide family annotation. Moreover, we show that the majority of RALF peptides are able to induce seedling or root growth inhibition in seedlings when applied exogenously as synthetic peptides. Additionally, we show that most of these responses are dependent on the RLK1-LIKE receptor kinase FERONIA, suggesting a pivotal role in the perception of multiple RALF peptides.