RESUMEN
Ectomycorrhizas are an intrinsic component of tree nutrition and responses to environmental variations. How epigenetic mechanisms might regulate these mutualistic interactions is unknown. By manipulating the level of expression of the chromatin remodeler DECREASE IN DNA METHYLATION 1 (DDM1) and two demethylases DEMETER-LIKE (DML) in Populus tremula × Populus alba lines, we examined how host DNA methylation modulates multiple parameters of the responses to root colonization with the mutualistic fungus Laccaria bicolor. We compared the ectomycorrhizas formed between transgenic and wild-type (WT) trees and analyzed their methylomes and transcriptomes. The poplar lines displaying lower mycorrhiza formation rate corresponded to hypomethylated overexpressing DML or RNAi-ddm1 lines. We found 86 genes and 288 transposable elements (TEs) differentially methylated between WT and hypomethylated lines (common to both OX-dml and RNAi-ddm1) and 120 genes/1441 TEs in the fungal genome suggesting a host-induced remodeling of the fungal methylome. Hypomethylated poplar lines displayed 205 differentially expressed genes (cis and trans effects) in common with 17 being differentially methylated (cis). Our findings suggest a central role of host and fungal DNA methylation in the ability to form ectomycorrhizas including not only poplar genes involved in root initiation, ethylene and jasmonate-mediated pathways, and immune response but also terpenoid metabolism.
Asunto(s)
Laccaria , Micorrizas , Populus , Micorrizas/fisiología , Árboles/genética , Árboles/metabolismo , Raíces de Plantas/metabolismo , Metilación de ADN/genética , ADN , Populus/metabolismo , Laccaria/genéticaRESUMEN
Plants are fixed organisms with continuous development throughout their life and great sensitivity to environmental variations. They react in this way by exhibiting large developmental phenotypic plasticity. This plasticity is partly controlled by (phyto)hormones, but recent studies also suggest the involvement of epigenetic mechanisms. It seems that these two factors may interact in a complex way and especially in the stem cells grouped together in meristems. The objective of this review is to present the current arguments about this interaction which would promote developmental plasticity. Three major points are thus addressed to justify this interaction between hormonal control and epigenetics (control at the chromatin level) for the developmental plasticity of plants: the arguments in favor of an effect of hormones on chromatin and vice versa, the arguments in favor of their roles on developmental plasticity and finally the arguments in favor of the central place of these interactions, the meristems. Various perspectives and applications are discussed.
TITLE: La plasticité développementale chez les plantes : une interaction entre hormones et épigénétique dans les cellules souches méristématiques. ABSTRACT: Les plantes sont des organismes fixés dont le développement est continu toute leur vie et qui ont une grande sensibilité aux variations environnementales. Elles réagissent ainsi en manifestant une importante plasticité phénotypique développementale. Cette plasticité est contrôlée pour partie par les (phyto)hormones mais des résultats récents suggèrent également l'implication des mécanismes épigénétiques. Ces deux facteurs interagiraient de manière complexe et notamment dans les cellules souches regroupées au niveau des méristèmes. L'objectif de cette revue est de présenter les arguments actuels concernant cette interaction qui favoriserait la plasticité développementale. Trois points majeurs sont ainsi abordés pour justifier cette interaction entre le contrôle hormonal et l'épigénétique (contrôle au niveau de la chromatine) pour la plasticité développementale des plantes : les arguments en faveur d'un effet des hormones sur la chromatine et vice-versa, les arguments en faveur de leurs rôles sur la plasticité développementale et enfin les arguments en faveur du lieu central de ces interactions, les méristèmes. Diverses perspectives et applications sont discutées.
