Abstract text: Xylella fastidiosa is a xylem-limited Gram-negative bacterium responsible for Olive Quick Decline Syndrome (OQDS), a major threat to olive production. The pathogen colonizes xylem vessels and forms biofilms that disrupt water transport, leading to leaf scorching, desiccation, and eventual tree death in susceptible cultivars1. The integrity and organization of the plant cell wall are central to vascular pathogen interactions, as wall remodelling influences both defence responses and tissue functionality2. Previous studies have shown that resistance to xylem-restricted pathogens is associated with constitutive differences in phenolic content and lignin composition, highlighting the potential contribution of intrinsic cell wall traits to disease outcomes3.

To assess whether similar mechanisms operate in the olive–X. fastidiosa pathosystem, we analysed cell wall composition in resistant (‘Favolosa’) and susceptible (‘Arbequina’) cultivars under control and infected conditions. Raman and FTIR spectroscopy were integrated with immunolocalization and ELISA to generate biochemical fingerprints and quantitatively map specific wall epitopes.

Our findings reveal cultivar-dependent and infection-associated differences in cell wall architecture, highlighting the combined contribution of constitutive traits and infection-induced remodelling to olive responses to X. fastidiosa.