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FRIMEDBIO-Fri prosj.st. med.,helse,biol

Recognition of danger signals in plant innate immunity

Alternative title: Gjenkjennelse av faresignaler i planters basale immunsystem

Awarded: NOK 4.4 mill.

Plants lack an adaptive immune system and are depending on their innate immunity to fight off pathogens. Pathogens are recognized either directly through conserved microbial molecules (PAMPs) or indirectly by the detection of plant derived molecules resulting from damage caused by the pathogen (DAMPs). The mechanisms underlying the recognition of PAMPs are widely studied, but the knowledge of the damage induced mechanisms are still little. In this project we have focused on a group of pathogen-activated secondary metabolites and whether these compounds can trigger an immunity response in the model organism Arabidopsis thaliana. These metabolites are known to be toxic to insects and pathogens, and displays phytotoxicity in higher doses. Our data show that these metabolites are able to trigger a transcriptomic response overlapping with the damage response, depending on the structure of the metabolite. Sublethal doses are also able to alter the physiology of the plant, suggesting that the plant also responds to these compounds. We also have results showing that these metabolites are able to alter the activity of certain proteins.

Å forstå hvordan planter kan tilpasse og forsvare seg mot sykdom og skadedyr i et klima stadig i endring er viktig i en verden hvor matsikkerhet bare vil bli mer og mer viktig. A. thaliana er i slekt med viktige matplanter, og kunnskap vi genererer i denne organismen kan overføres til andre og mer matnyttige vekster. Kunnskap om hvordan disse plantene responderer og håndterer sykdom er viktig og danner grunnlaget for å lage bærekraftige, robuste matplanter.

Plants have to rely on their innate immune system to fight off pathogen attacks as they, unlike animals, do not possess an adaptive immune system or mobile defender cells. Plants can sense the presence of pathogens by perceiving danger signals generated b y damage of the plant tissue and compounds resulting from pathogen activity. However, the molecular mechanisms underlying the perception and transmission of these signals and the defence response that they eventually trigger are not yet known. Glucosinola tes are a characteristic group of secondary metabolites in Brassicaceae plants which are hydrolysed into glucosinolate hydrolysis products (GHPs) upon tissue damage. GHPs have been found to covalently bind to cysteines of target proteins in human/animal s ystems and thereby regulate cellular functions. Preliminary transcriptional profiling of Arabidopsis thaliana seedlings exposed to GHPs indicates that multiple systems are influenced/regulated by GHPs including e.g. generation of ROS expression of heat sh ock transcription factors and proteins, and genes affecting plant defence activities. In this project we aim to elucidate how GHPs act as damage-activated molecular effectors signalling danger to a plant. We will monitor molecular responses to wounding a nd treatment with GHPs in the model plants Arabidopsis thaliana and Nicotiana tabacum. A click chemistry approach will be used to identify plant proteins that are covalently modified by GHPs during danger signalling. Luciferase reporter systems will be us ed to monitor the propagation and dynamics of the signal within the plant and signalling to and responses in non-damaged surrounding plants. Finally, the ability of GHPs to prime the plant defence response will be tested with the microbial hemibiotrophic pathogen Pseudomonas syringae and the fungal necrotrophic pathogen Botrytis cinerea.

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FRIMEDBIO-Fri prosj.st. med.,helse,biol

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