NLR we there yet? Nucleocytoplasmic coordination of NLR-mediated immunity

Abstract

Plant intracellular nucleotide-binding leucine-rich repeat immune receptors (NLRs) perceive theactivity of pathogen-secreted effector molecules that, when undetected, promote colonisation ofhosts.SignallingfromactivatedNLRsconvergeswithandpotentiatesdownstreamresponsesfromactivated pattern recognition receptors (PRRs) that sense microbial signatures at the cell surface.Efficient signalling of both receptor branches relies on the host cell nucleus as an integration pointfor transcriptional reprogramming, and on the macromolecular transport processes that mediatethe communication between cytoplasm and nucleoplasm. Studies on nuclear pore complexes(NPCs), the nucleoporin proteins (NUPs) that compose NPCs, and nuclear transport machineryconstituentsthatcontrolnucleocytoplasmictransport,haverevealedthattheyplayimportantrolesin regulating plant immune responses. Here, we discuss the contributions of nucleoporins andnucleartransportreceptor(NTR)-mediatedsignaltransductioninplantimmunitywithanemphasison NLR immune signalling across the nuclear compartment boundary and within the nucleus. Wealso highlight and discuss cytoplasmic and nuclear functions of NLRs and their signalling partnersandfurtherconsiderthepotentialimplicationsofNLRactivationandresistosomeformationinbothcellular compartments for mediating plant pathogen resistance and programmed host cell deat.