A long‑term FACE experiment exposing 180‑year‑old Quercus robur to +150 ppm CO₂ showed seasonal declines in powdery mildew and insect herbivory but no consistent change in biotic stress incidence. Metabolomic analyses revealed widespread shifts in amino acid, Coenzyme A, and redox pathways, indicating extensive metabolic plasticity without altered resistance to pathogens or herbivores.

The study shows that silencing of NOR2 rRNA genes in Arabidopsis thaliana depends primarily on CHH-context cytosine methylation, particularly mediated by CMT2 and the chromatin remodeler DDM1, rather than CG or CHG methylation. Comparative promoter analysis revealed a prevalence of CHH sites in plant rDNA promoters, explaining why CHH methylation mutants disrupt NOR2 silencing more strongly, while NOR2 loci are hyper‑methylated and more condensed than NOR4.