Multi-tasking of somatic embryogenesis receptor-like protein kinases

Receptor-like protein kinases (RLKs) are transmembrane proteins crucial for cell-to-cell and cell-to-environment communications. The extracellular domain of a RLK is responsible for perception of a specific extracellular ligand to trigger a unique intercellular signaling cascade, often via phosphorylation of cellular proteins. The signal is then transduced to the nucleus of a cell where it alters gene expression. There are more than 610 RLKs in Arabidopsis thaliana, only a handful of them have been functionally characterized. This review focuses on recent advances in our understanding of a small group of RLKs named somatic embryogenesis receptor-like protein kinases (SERKs). SERKs act as coreceptors in multiple signaling pathways via their physical interactions with distinct ligand-binding RLKs.

Research highlights▶ SERKs act as coreceptors in regulating multiple signaling pathways. ▶ The LRR-RLK BAK1 and other related SERKs interact with the major steroid receptor BRI1. ▶ Multiple SERKs interact with the LRR-RLK BIR1 to regulate cell death. ▶ SERK1 and SERK2 are required for development of anthers and could interact with the LRR-RLK EXS1/EMS1. ▶ BAK1 interacts with multiple receptor kinases in innate immunity, including FLS2, EFR, PEPR1 and PEPR2. ▶ BAK1 is the target of secreted bacterial effectors in effector-triggered immunity.