Probing Plant Receptor Kinase Functions with Labeled Ligands

Plant cells rely on numerous membrane-localized receptor kinases for communication with each other as well as with the environment to ensure coordinated growth, development and survival. Additionally, several families of small secreted peptides have been identified in plants that possibly regulate various developmental processes through activation of specific membrane receptor kinases. In research efforts to elucidate the underlying signaling processes in plants, it has become obvious that knowledge of both the extracellular ligand and its corresponding receptor(s) is a prerequisite to understand cell communication. Of more than 1,000 orphan peptides in plants, only a few have been functionally characterized and paired with their respective receptors. Here, we discuss recent advances made in the field of receptor-ligand pairing and visualization in plant cells by means of chemically labeled ligands. We summarize and compare various chemical strategies from the mammalian field that can be employed to extend our understanding of the plant receptor kinase functions in plants.