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Priming plants for biotic and abiotic stress resistance:investigating possible mechanisms
Responsable du projet Brigitte Mauch Mani
Gaëtan Glauser

Reinhard Neier
   
Collaborateur Dirk Balmer
Victoria Pastore Fuentes
   
Résumé Plants treated with the non-protein amino acid beta-aminobutyric acid (BABA) develop an enhanced defensive capacity against a large variety of biotic and abiotic stresses. The expression of this BABA-induced resistance (BABA-IR) coincides with a faster and stronger defense response following pathogen attack or abiotic stress. This phenomenon has been termed “priming, sensitization or potentiation”, and the underlying mechanisms are starting to become clearer. Priming has been proposed to be based on the accumulation of signalling proteins in an inactive form that would then be activated upon exposure to stress. Another suggestion was the accumulation of transcription factors in primed plants leading to an enhanced defense gene transcription when this plant is stressed and, recently, evidence has been pointing to changes at the epigenetic level. We have previously isolated mutants of Arabidopsis impaired in the expression of BABA-IR. Besides demonstrating that there is a genetic basis for the observed induced resistance and priming, the analysis of these mutants also allowed to start dissecting the signalling pathways involved in the phenomenon, demonstrating that BABA-IR against biotic and abiotic stresses is based on priming of distinct defense signaling mechanisms involving salicylic acid-, abscisic acid-, and phosphoinositide-dependent pathways and that callose deposition plays an important role. Here, we propose to take advantage of the recently established Chemical Analysis Platform at our university and ensuing expertise to look at the fate of BABA in plants, i.e. determine its perseverance, concentration and possible catabolism and to develop a sensitive, accurate methodology to determine hormones and their conjugates as well as other metabolite levels in plants. Such methods will enable us to determine the role of fine-tuning of the hormonal homeostasis during BABA-IR and induced resistance in general. Conjugation of hormones is a way of controlling the cellular level of these substances and we have preliminary results showing that conjugation reactions might contribute to BABA-IR as well as basic immunity of Arabidopsis against Pseudomonas syringae. In a second approach we propose to investigate the duration of induced resistance and priming after an inducing treatment. Our own results as well as recent presentations by colleagues at scientific meetings point to the possibility that the primed state might be transferred to the descendants of primed plants. Here we propose to establish whether this is the case for different IR systems and against various biotic and abiotic stresses. We plan to screen WT populations of Arabidopsis for accessions showing a “hypo- or hyper-long-time priming” phenotype in view of establishing the genetic basis. We will also investigate the dependency of the phenomenon on defined signalling pathways and genes known to be central for the expression of IR. Finally, we will determine whether there is a possibility that the observed phenomenon is due to transfer of BABA or derivates, or of an eventual bacteria-generated or induced molecule through the seeds to the next generation. If the observed trans-generation priming can be unequivocally attributed to a transfer of the primed state to the descendants of a plant, our results and generated plant populations will be the starting point for later investigations into the molecular mechanisms behind the observed phenomenon. Priming-inducing events or treatments conferring enhanced resistance against both biotic and abiotic stresses with minimal inhibitory effects on commercially important traits are of interest to have a means of transferring useful adaptations to a following generation, both in natural as in agricultural ecosystems.
   
Mots-clés transgeneration priming, duration of priming, induced resistance
   
Type de projet Recherche fondamentale
Domaine de recherche Botanique
Source de financement FNS - Encouragement de projets (Div. I-III)
Etat Terminé
Début de projet 1-5-2012
Fin du projet 30-4-2015
Budget alloué 502'000.00
Autre information http://p3.snf.ch/projects-140593#
Contact Brigitte Mauch-Mani