RESUMO
Quantitative disease resistance, often influenced by environmental factors, is thought to be the result of DNA sequence variants segregating at multiple loci. However, heritable differences in DNA methylation, so-called transgenerational epigenetic variants, also could contribute to quantitative traits. Here, we tested this possibility using the well-characterized quantitative resistance of Arabidopsis to clubroot, a Brassica major disease caused by Plasmodiophora brassicae. For that, we used the epigenetic recombinant inbred lines (epiRIL) derived from the cross ddm1-2 × Col-0, which show extensive epigenetic variation but limited DNA sequence variation. Quantitative loci under epigenetic control (QTLepi ) mapping was carried out on 123 epiRIL infected with P. brassicae and using various disease-related traits. EpiRIL displayed a wide range of continuous phenotypic responses. Twenty QTLepi were detected across the five chromosomes, with a bona fide epigenetic origin for 16 of them. The effect of five QTLepi was dependent on temperature conditions. Six QTLepi co-localized with previously identified clubroot resistance genes and QTL in Arabidopsis. Co-localization of clubroot resistance QTLepi with previously detected DNA-based QTL reveals a complex model in which a combination of allelic and epiallelic variations interacts with the environment to lead to variation in clubroot quantitative resistance.
Assuntos
Arabidopsis/genética , Arabidopsis/imunologia , Resistência à Doença/genética , Epigênese Genética , Variação Genética , Doenças das Plantas/genética , Doenças das Plantas/microbiologia , Arabidopsis/crescimento & desenvolvimento , Arabidopsis/microbiologia , Sequência de Bases , Metilação de DNA/genética , Padrões de Herança/genética , Mutação/genética , Fenótipo , Plasmodioforídeos/fisiologia , Locos de Características Quantitativas/genética , TemperaturaRESUMO
Clubroot caused by the protist Plasmodiophora brassicae is a major disease affecting cultivated Brassicaceae. Using a combination of quantitative trait locus (QTL) fine mapping, CRISPR-Cas9 validation, and extensive analyses of DNA sequence and methylation patterns, we revealed that the two adjacent neighboring NLR (nucleotide-binding and leucine-rich repeat) genes AT5G47260 and AT5G47280 cooperate in controlling broad-spectrum quantitative partial resistance to the root pathogen P. brassicae in Arabidopsis and that they are epigenetically regulated. The variation in DNA methylation is not associated with any nucleotide variation or any transposable element presence/absence variants and is stably inherited. Variations in DNA methylation at the Pb-At5.2 QTL are widespread across Arabidopsis accessions and correlate negatively with variations in expression of the two genes. Our study demonstrates that natural, stable, and transgenerationally inherited epigenetic variations can play an important role in shaping resistance to plant pathogens by modulating the expression of immune receptors.
Assuntos
Arabidopsis , Resistência à Doença , Doenças das Plantas , Arabidopsis/genética , Arabidopsis/imunologia , Doenças das Plantas/genética , Doenças das Plantas/imunologia , Doenças das Plantas/parasitologia , Resistência à Doença/genética , Proteínas NLR/genética , Proteínas NLR/metabolismo , Metilação de DNA , Plasmodioforídeos/fisiologia , Locos de Características Quantitativas/genética , Proteínas de Arabidopsis/genética , Epigênese Genética , Regulação da Expressão Gênica de Plantas , Genes de Plantas , AlelosRESUMO
Type-2 HDACs (HD2s) are plant-specific histone deacetylases that play diverse roles during development and in responses to biotic and abiotic stresses. In this study we characterized the six tobacco genes encoding HD2s that mainly differ by the presence or the absence of a typical zinc finger in their C-terminal part. Of particular interest, these HD2 genes exhibit a highly conserved intron/exon structure. We then further investigated the phylogenetic relationships among the HD2 gene family, and proposed a model of the genetic events that led to the organization of the HD2 family in Solanaceae. Absolute quantification of HD2 mRNAs in N. tabacum and in its precursors, N. tomentosiformis and N. sylvestris, did not reveal any pseudogenization of any of the HD2 genes, but rather specific regulation of HD2 expression in these three species. Functional complementation approaches in Arabidopsis thaliana demonstrated that the four zinc finger-containing HD2 proteins exhibit the same biological function in response to salt stress, whereas the two HD2 proteins without zinc finger have different biological function.