Endogenous peptide ligand–receptor systems for diverse signaling networks in plants

• A range of ligand specificity of receptors allows complex peptide–receptor combinations.
• Peptides and phytohormones make signaling networks.
• Peptide signaling mediates environmental responses to modulate developmental processes.

Endogenous peptide ligand–receptor systems regulate cell–cell communications in various developmental processes in plants. Recent studies have revealed that the peptide–receptor combinations are not simply one-on-one with single roles. One peptide activates multiple downstream signaling through different receptors, while one receptor transmits different signals depending on peptide partners. Peptide signaling pathways also crosstalk with signaling pathways of phytohormones such as auxin, cytokinin and brassinosteroids. Furthermore, environmental cues such as temperature, nutrient, and microbes activate or inactivate peptide signaling pathways, which in turn modulate developmental processes. This report summarizes recent advance on peptide–receptor signaling, which makes a signaling network with phytohormone signaling pathways and environmental responses.