Ionomic Signatures of Olive Trees Affected by Quick Decline Syndrome

Olive Quick Decline Syndrome (OQDS), caused by the bacterium Xylella fastidiosa, subsp. pauca, has devastated olive groves in Italy's Apulia region since 2013. Despite significant scientific progress, the solution remains elusive. This study investigated the link between olive tree nutritional status and OQDS severity, aiming to uncover potential mitigation strategies. We analyzed leaf nutrient profiles from olive trees in naturally infected areas, categorizing them as asymptomatic (AS), mildly symptomatic (MS), or severely symptomatic (SS). Distinct nutritional differences were observed across these groups. The integration of univariate statistical analysis, hierarchical clustering, and Principal Component Analysis (PCA) revealed a complex relationship between plant nutritional status and disease progression. Notably, the PCA results highlighted the importance of sulfur metabolism, suggesting its role in olive trees' defense mechanisms and metabolic responses to OQDS. These results provide promising evidence with potential application for dealing with OQDS, and the question of whether plant nutritional status plays a role in the development of OQDS symptoms deserves to be further examined in depth.