DNA methylation landscapes before and after Pacific Oyster Mortality Syndrome are different within and between resistant and susceptible Magallana gigas

• Published in: Science of The Total Environment
• Main Authors: Valdivieso, Alejandro, Morga, Benjamin, Degremont, Lionel, Mege, Mickaël, Courtay, Gaëlle, Dorant, Yann, Escoubas, Jean-Michel, Gawra, Janan, de Lorgeril, Julien, Mitta, Guillaume, Cosseau, Celine, Vidal-Dupiol, Jeremie
• Format: Article in Journal/Newspaper
• Language: English
• Published: Elsevier 2025
• Subjects: POMS; DNA methylation; Epibiomarkers; Immune response; OsHV-1 μVar; Oyster; Ensure healthy lives and promote well-being for all at all ages; Ensure availability and sustainable management of water and sanitation for all; Build resilient infrastructure; promote inclusive and sustainable industrialization and foster innovation; Pacific; Guillaume; Pacific oyster
• Online Access: http://hdl.handle.net/10261/376905; https://doi.org/10.1016/j.scitotenv.2025.178385; https://api.elsevier.com/content/abstract/scopus_id/85214530260

Pacific oysters face recurring outbreaks of Pacific Oyster Mortality Syndrome (POMS), a polymicrobial multifactorial disease. Although this interaction is increasingly understood, the role of epigenetics (e.g., DNA methylation) appears to be of fundamental importance because of its ability to shape oyster resistance/susceptibility and respond to environmental triggers, including infections. In this context, we comprehensively characterized basal (no infection) and POMS-induced changes in the methylome of resistant and susceptible oysters, focusing on the gills and mantle. Our analysis identified differentially methylated regions (DMRs) that revealed distinct methylation patterns uniquely associated with the susceptible or resistant phenotypes in each tissue. Enrichment analysis of genes bearing DMRs highlighted that these epigenetic changes were specifically linked to immunity, signaling, metabolism, and transport. Notably, 31 genes with well-known immune functions were differentially methylated after POMS, with contrasting methylation patterns between the phenotypes. Based on the methylome differences between phenotypes, we identified a set of candidate epibiomarkers that could characterize whether an oyster is resistant or susceptible (1998 candidates) and whether a site has been exposed to POMS (164 candidates). Overall, the findings provide a deeper understanding of the molecular interactions between oysters and POMS infection, opening new questions about the broader implications of epigenetic mechanisms in host-pathogen dynamics and offering promising strategies for mitigating the impacts of this devastating disease. Beyond its biological aspects, this study provides insights into potential epigenetic biomarkers for POMS disease management and targets for enhancing oyster health and productivity. The present study was supported by the FEAMP Gestinnov (FFEA470020FA1000007) to Jeremie Vidal-Dupiol, ANR DECIPHER (ANR-14-CE19-0023), and ANR DECICOMP (ANR-19-CE20-0004) to Guillaume Mitta. This study is set ...