CEP hormones at the nexus of nutrient acquisition and allocation, root development, and plant-microbe interactions.

A growing understanding is emerging of the roles of peptide hormones in local- and long-distance signalling that coordinates plant growth and development as well as responses to the environment. C-TERMINALLY ENCODED PEPTIDE (CEP) signalling triggered by its interaction with CEP RECEPTOR 1 (CEPR1) is known to play roles in systemic nitrogen (N)-demand signalling, legume nodulation, and root system architecture. Recent research provides further insight into how CEP signalling operates, which involves diverse downstream targets and interactions with other hormone pathways. Additionally, there is emerging evidence of CEP signalling playing roles in N-allocation, root responses to carbon levels, the uptake of other soil nutrients such as phosphorus and sulphur, root responses to arbuscular mycorrhizal fungi, plant immunity, and reproductive development. These findings suggest CEP signalling more broadly coordinates growth across the whole plant in response to diverse environmental cues. Moreover, CEP signalling and function appears to be conserved in angiosperms. In this manuscript, we review the recent advances in CEP biology with a focus on soil nutrient uptake, root system architecture and organogenesis, and roles in plant-microbe interactions. Furthermore, we address knowledge gaps and future directions in this research field.