title: Evolutionary tinkering of the expression of PDF1s suggests their joint effect on zinc tolerance and the response to pathogen attack.
abstract: Multigenic families of Plant Defensin type 1 (PDF1) have been described in several species, including the model plant Arabidopsis thaliana as well as zinc tolerant and hyperaccumulator A. halleri. In A. thaliana, PDF1 transcripts (AtPDF1) accumulate in response to pathogen attack following synergic activation of ethylene/jasmonate pathways. However, in A. halleri, PDF1 transcripts (AhPDF1) are constitutively highly accumulated. Through an evolutionary approach, we investigated the possibility of A. halleri or A. thaliana species specialization in different PDF1s in conveying zinc tolerance and/or the response to pathogen attack via activation of the jasmonate (JA) signaling pathway. The accumulation of each PDF1 from both A. halleri and A. thaliana was thus compared in response to zinc excess and MeJA application. In both species, PDF1 paralogues were barely or not at all responsive to zinc. However, regarding the PDF1 response to JA signaling activation, A. thaliana had a higher number of PDF1s responding to JA signaling activation. Remarkably, in A. thaliana, a slight but significant increase in zinc tolerance was correlated with activation of the JA signaling pathway. In addition, A. halleri was found to be more tolerant to the necrotrophic pathogen Botrytis cinerea than A. thaliana. Since PDF1s are known to be promiscuous antifungal proteins able to convey zinc tolerance, we propose, on the basis of the findings of this study, that high constitutive PDF1 transcript accumulation in A. halleri is a potential way to skip the JA signaling activation step required to increase the PDF1 transcript level in the A. thaliana model species. This could ultimately represent an adaptive evolutionary process that would promote a PDF1 joint effect on both zinc tolerance and the response to pathogens in the A. halleri extremophile species.
authors.affiliation: Unité Mixte de Recherche, Biochimie et Physiologie Moléculaire des Plantes, Montpellier SupAgro/CNRS/INRA/Université Montpellier II Montpellier, France.
authors.forename: Nga N T
authors.initials: NN
authors.lastname: Nguyen
authors.affiliation: Unité Mixte de Recherche, Amélioration Génétique et Adaptation des Plantes Méditerranéennes et Tropicales, Montpellier SupAgro/CIRAD/INRA Montpellier, France.
authors.forename: Vincent
authors.initials: V
authors.lastname: Ranwez
authors.affiliation: Laboratoire d'Ecophysiologie des Plantes sous Stress Environnementaux (LEPSE), UMR759 INRA/SupAgro Montpellier, France.
authors.forename: Denis
authors.initials: D
authors.lastname: Vile
authors.affiliation: Laboratoire des Interactions Plantes-Pathogènes, Unité Mixte de Recherche 217, Université Pierre et Marie Curie (UPMC Univ. Paris 06) Paris, France.
authors.forename: Marie-Christine
authors.initials: MC
authors.lastname: Soulié
authors.affiliation: Laboratoire des Interactions Plantes-Pathogènes, Unité Mixte de Recherche 217 INRA/AgroParisTech/UPMC Paris, France.
authors.forename: Alia
authors.initials: A
authors.lastname: Dellagi
authors.affiliation: Laboratoire des Interactions Plantes-Pathogènes, Unité Mixte de Recherche 217 INRA/AgroParisTech/UPMC Paris, France.
authors.forename: Dominique
authors.initials: D
authors.lastname: Expert
authors.affiliation: Unité Mixte de Recherche, Biochimie et Physiologie Moléculaire des Plantes, Montpellier SupAgro/CNRS/INRA/Université Montpellier II Montpellier, France.
authors.forename: Françoise
authors.initials: F
authors.lastname: Gosti
keywords: MeJA; arabidopsis halleri; biotic and abiotic stress on plants; defensins; elementary defence and joint effect; gene duplication and evolution; zinc tolerance