The receptor kinase FER is a RALF-regulated scaffold controlling plant immune signaling

Small peptides allow rapid responses RALFs (rapid alkalinization factors), a family of small peptides in plants, are produced in response to rapidly changing conditions. Stegmann et al. studied the agility and diversity built into this signaling network. Some RALFs, such as RALF23 and its relative RALF33, are activated by proteolytic cleavage. Others, such as RALF32, are not. RALF23 and RALF33 are called into play after a pathogen triggers immune responses. RALF32, on the other hand, regulates seedling growth. All three of these RALFs use the same receptor kinase, which can interact with other signaling components. Thus, plant responses can be fine-tuned by rapid release of peptides. Science , this issue p. 287