A mycorrhiza-associated receptor-like kinase with an ancient origin in the green lineage

Receptor-like kinases (RLKs) are key cell signaling components. The rice ARBUSCULAR RECEPTOR-LIKE KINASE 1 (OsARK1) regulates the arbuscular mycorrhizal (AM) association postarbuscule devel-opment and belongs to an undefined subfamily of RLKs. Our phy-logenetic analysis revealed that ARK1 has an ancient paralogue in spermatophytes, ARK2. Single ark2 and ark1/ark2 double mu-tants in rice showed a nonredundant AM symbiotic function for OsARK2. Global transcriptomics identified a set of genes coregu-lated by the two RLKs, suggesting that OsARK1 and OsARK2 or-chestrate symbiosis in a common pathway. ARK lineage proteins harbor a newly identified SPARK domain in their extracellular re-gions, which underwent parallel losses in ARK1 and ARK2 in monocots. This protein domain has ancient origins in streptophyte algae and defines additional overlooked groups of putative cell surface receptors.

Automated summary

Receptor-like kinases play crucial roles in plant cell signaling, with OsARK1 and OsARK2 genes in rice regulating arbuscular mycorrhizal symbiosis. These two genes cooperate in symbiosis by co-regulating a set of genes in a common pathway.