Abstract text: CITRUSBUSTERS is a Horizon Europe project developing integrated and sustainable strategies to prevent and control two major emerging citrus diseases: Huanglongbing (HLB), caused by the bacterium Candidatus Liberibacter asiaticus and transmitted by psyllids already present in Europe, and Citrus Black Spot (CBS), caused by the fungal pathogen Phyllosticta citricarpa. The project focuses on preventive approaches, including innovative biochemical strategies that exploit citrus residues as natural sources of immunity-activating compounds. Citrus peel by-products are processed through milling, subcritical water extraction, and controlled enzymatic digestion to generate complex biofractions enriched in oligosaccharides acting as plant Damage-Associated Molecular Patterns (DAMPs). These biofractions are screened for elicitor activity using Arabidopsis reporter lines to monitor calcium influxes as early immune signalling event. Extracts from both fresh and dried peels display stable and reproducible immune-inducing activity, which depends on extraction parameters. To elucidate the biochemical nature of the active components, analytical approaches such as HPIC profiling, proteinase K digestion, TLC, and genetic assays using receptor-impaired mutant lines are combined. The most active fractions will be further characterized and tested in protection assays under controlled laboratory conditions and validated in citrus infection systems against HLB and CBS, aiming to deliver scalable, nature-based preventive solutions for citrus production.