How a single receptor‑like kinase exerts diverse roles:lessons from FERONIA

FERONIA(FER)is a member of the Catharanthus roseus receptor-like kinase 1-like(CrRLK1L)protein subfamily,which participates in reproduction,abiotic stress,biotic stress,cell growth,hormone response,and other molecular mecha-nisms of plants.However,the mechanism by which a single RLK is capable of mediating multiple signals and activat-ing multiple cellular responses remains unclear.Here,we summarize research progress revealing the spatial–temporal expression of FER,along with its co-receptors and ligands determined the function of FER signaling pathway in multiple organs.The specificity of the FER signaling pathway is proposed to operate under a four-layered mechanism:(1)Spatial–temporal expression of FER,co-receptors,and ligands specify diverse functions,(2)Specific ligands or ligand combinations trigger variable FER signaling pathways,(3)Diverse co-receptors confer diverse FER perception and response modes,and(4)Unique downstream components that modify FER signaling and responses.Moreover,the regulation mechanism of the signaling pathway-appears to depend on the interaction among the ligands,RLK receptors,co-receptors,and downstream components,which may be a general mechanism of RLKs to maintain signal specificity.This review will provide a insight into understanding the specificity determination of RLKs signaling in both model and horticultural crops.

OsRbohI is the indispensable NADPH oxidase for molecular-patterns-induced reactive oxygen species production in rice

Dear Editor,The rapid generation of reactive oxygen species(ROS),or ROS burst,is a key feature of pathogen-associated molecular patterns(PAMPs)-triggered immunity,which is mediated by plasma membrane resident respiratory burst oxidase homologs(Rbohs)in plants(Wang et al.,2020).In Arabidopsis,AtRbohD is a well-documented Rboh responsible for PAMP-triggered ROS bursts,with mutations in AtRbohD leading to an abolished ROS response upon PAMP treatments.In rice,OsRbohB has been extensively studied and initially considered the counterpart to AtRbohD(Wong et al.,2007;Fan et al.,2018;Wang et al.,2020;Li et al.,2022;Wang and Kawano,2022).However,our results indicate that mutations in OsRbohB do not affect ROS bursts,whereas OsRbohI mutants show a complete absence of ROS bursts.Consistently,OsRbohI,but not OsRbohB or OsRbohE,can complement the defect in Arabidopsis AtRbohD mutant in PAMP-triggered ROS bursts,demonstrating inter-class conservation in ROS regulation.Moreover,mutations in OsRbohI result in dramatically reduced resistance to rice blast.In addition,phosphorylation occurs at crucial and conserved serine sites in OsRbohI.Altogether,these results suggest that OsRbohI is the indispensable Rboh member for PAMP-induced ROS bursts in rice innate immunity.