Investigating the functional diversification of a conserved plant peptide-receptor kinase signaling module

• Applicant: Dr. Oliver Johanndrees
• Subject Area: Plant Physiology ; Plant Breeding and Plant Pathology
• Term: since 2023
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 537740606

Hundreds of potential secreted signaling peptides are predicted in plants, but only a handful of them are functionally characterized and have cognate receptors. The host group has recently identified a family of stress-responsive secreted signaling peptides, called CTNIPs after a conserved amino acid motif, and their corresponding receptor HAESA-LIKE 3 (HSL3), a leucine-rich repeat receptor kinase. Notably, the CTNIP-HSL3 signaling module is conserved across flowering plants (Angiosperms), including most Monocots. Interestingly, phylogenetic analyses indicate that grasses (Poaceae) and legumes (Fabaceae) contain expanded HSL3 repertoires. Bona fide CTNIP sequences could however not be identified in Poaceae. These observations beg the question as to how CTNIPs and HSL3 might have diverged during plant evolution, which (CTNIP-like) peptides are perceived by HSL3 homologs in grasses, and importantly what the biological functions of expanded HSL3 repertoires are. Poaceae contain some of the species most intensively used for agriculture worldwide. It is therefore of major interest to establish how this conserved signaling pathway works in grasses and how it might have diverged from other plants. Furthermore, the project aims to understand what drives HSL3 ligand-recognition specificity, as it was shown that CTNIP peptides are specifically recognized by HSL3 homolog derived from the same plant species. Because it is conserved across multiple plant clades, the CTNIP-HSL3 signaling module provides an ideal platform to study peptide-receptor co-evolution, and generally understand how novel ligand-binding specificities in plant receptor kinases occur. Beyond fundamental knowledge, results generated within this project might open possibilities to engineer universally recognized CTNIP variants, which could find application as bio-stimulants in agriculture.

• DFG Programme: WBP Fellowship
• International Connection: Switzerland
• Host: Professor Dr. Cyril Zipfel