Priming for seagrass resilience: DNA methylation and transcriptomic insights into heat stress memory in Posidonia oceanica seedlings

Priming, a process that enables plants to 'remember' past stress and improve responses to future stressors, is underexplored in seagrasses. This study investigated gene expression and DNA methylation in Posidonia oceanica seedlings during priming and subsequent heat stress (triggering), marking the first analysis of priming regulation in this species. Priming induced significant transcriptomic alterations, including the activation of DNA repair and metabolic pathways, which may underlie the enhanced resilience to repeated thermal stress that was observed previously. Primed seedlings invested more in growth, in comparison with nonprimed ones, prioritizing stress response. The findings reveal key molecular and epigenetic mechanisms involved in thermal response, opening pathways for stress memory research in marine plants and supporting their potential role in ecological adaptation and restoration efforts.