Rôles des variations épigénétiques transgénérationnelles dans la résistance quantitative à la hernie chez Arabidopsis thaliana

Abstract : Recent studies have shown that plant epigenome variability is an important factor in plant response to abiotic and biotic stress. Clubroot caused by the protist Plasmodiophora brassicae is a major disease of Brassicaceae whose quantitative resistance is supposed to result from many allele segregation. The aim of my work is to understand if, in Arabidopsis thaliana, an inherited epigenetic variability can lead to variations in clubroot resistance. For that, an untargeted approach of quantitative epigenetics was carried out using the epiRIL population ddm1-2 x Col-0. Seventeen QTL under epigenetic control (QTLepi), clustered in 6 genomic regions, were detected, 5 of them being temperature-dependant.Finally, two regions previously identified as involved in clubroot response were finely studied. The region of the major clubroot resistance gene RPB1, which colocalizes with three QTLepi, shows major genomic variations in Arabidopsis ecotypes potentially due to movements of transposable elements. The QTL Pb-At5.2 is depending on one epimutation controlling the methylation state and the expression of two NLR genes. The results obtained demonstrate that the clubroot quantitative resistance is associated with inherited stable DNA methylation variations suggesting a complex model of resistance regulation where favourable alleles and epialleles association is necessary to obtain an optimal resistance.
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Benjamin Liegard. Rôles des variations épigénétiques transgénérationnelles dans la résistance quantitative à la hernie chez Arabidopsis thaliana. Génétique des plantes. Agrocampus Ouest, 2018. Français. ⟨NNT : 2018NSARC137⟩. ⟨tel-02303309⟩

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