RGF1 INSENSITIVE 1 to 5, a group of LRR receptor-like kinases, are essential for the perception of root meristem growth factor 1 in Arabidopsis thaliana

Signature motif-guided identification of receptors for peptide hormones essential for root meristem growth

“…In addition, an accompanying study [31] identified the same five LRR-RLKs as receptors for RGFs by using a completely different approach from ours, further supporting the validity of our biochemical assay for matching of receptors and their ligands. In conclusion, our study not only identifies RGF receptors and reveals SERKs as co-receptors with RGFRs, but also opens the possibility of matching other XI LRR-RK members with their ligands using the conserved R-x-R motif.…”

Peptide signaling in plants: finding partners is the key

“…These data strongly suggest that RGIs mediate the action of RGFs to activate PLT pathway to maintain the meristem size. Ou et al [9] further demonstrated a direct interaction between RGF peptide and the extracellular domain of RGI1 protein using pull-down and dot blotting assays. More interestingly, they observed that exogenous application of RGF1 rapidly induces phosphorylation and ubiquitination of RGI1 in planta, typical consequences of ligand-receptor interactions [9].…”

“…Because mutations in these RLKs (belonging to LRR-RLK subfamily XI), like the triple mutants of BAK1-related kinases, also resulted in short-root phenotype, they hypothesized that these RLKs may serve as receptors for signaling molecules that control root growth, such as RGFs. Indeed, in the RGF1 response assay, these RLK mutants became insensitive, and they named the five LRR-RLKs as RGIs for RGF-INSENSITIVES [9]. Ou et al performed exhaustive genetic analysis of these five RGIs by generating a series of double, triple, quadruple, and quintuple mutants and thoroughly recorded the root growth defects.…”

“…When studying BR signaling with serk1 serk2 bak1 and serk1 bak1 bkk1 triple null mutants, Du et al [8] has noticed in these mutants a short-root phenotype that is BR independent. Through a yeast two-hybrid screen, Ou et al [9] identified five closely related LRR-RLKs that interacted with BAK1. Because mutations in these RLKs (belonging to LRR-RLK subfamily XI), like the triple mutants of BAK1-related kinases, also resulted in short-root phenotype, they hypothesized that these RLKs may serve as receptors for signaling molecules that control root growth, such as RGFs.…”

Ancient microRNA families that regulate transcription factors are preferentially preserved during plant radiation

“…Other large gene families, for instance, RLKs or ubiquitins, mainly regulate cell response or growth via signaling transduction at protein modification level, which proceed much faster than regulation by transcription and translation. [11][12][13] Assuming that, during the brassinosteroid signaling, a miRNA was evolved to regulate the mRNA of a RLK (such as BRI1) and the RLK can regulate miRNA level through signaling transduction via downstream TFs (for example BES1), this assumed regulatory loop would be less efficient than a peptide or protein to directly modify the signaling of the RLK or a miRNA to regulate the mRNA level of the downstream TF. 14,15 Taken together, these points might be the reasons why we observed more TF-associated miRNAs than other functional miRNAs being conserved in the plant genomes.…”