Hop stunt viroid infection induces heterochromatin reorganization
2024
Marquez, Joan | Marquez Molins, Joan | Cheng, Jinping | Juárez González, Vasti Thamara | Annacondia López, María Luz | Martinez-Arias, Germán
Viroids are pathogenic noncoding RNAs that completely rely on their host molecularmachinery to accomplish their life cycle. Several interactions between viroids and their hostmolecular machinery have been identified, including interference with epigenetic mechanismssuch as DNA methylation. Despite this, whether viroids influence changes in other epigeneticmarks such as histone modifications remained unknown. Epigenetic regulation is particularlyimportant during pathogenesis processes because it might be a key regulator of the dynamismof the defense response. Here we have analyzed the changes taking place in Cucumis sativus (cucumber) facultativeand constitutive heterochromatin during hop stunt viroid (HSVd) infection using chromatinimmunoprecipitation (ChIP) of the two main heterochromatic marks: H3K9me2 andH3K27me3. We find that HSVd infection is associated with changes in both H3K27me3 and H3K9me2,with a tendency to decrease the levels of repressive epigenetic marks through infection pro-gression. These epigenetic changes are connected to the transcriptional regulation of theirexpected targets, genes, and transposable elements. Indeed, several genes related to thedefense response are targets of both epigenetic marks. Our results highlight another host regulatory mechanism affected by viroid infection, pro-viding further information about the complexity of the multiple layers of interactions betweenpathogens/viroids and hosts/plants.
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