A multi-factorial strategy is required to co-exist with X. fastidiosa infections, which are
devastating olive trees in the southern area of Apulia (Italy). Observations in the outbreak area can
provide information on potential approaches for containment. Olive cvs Leccino and FS17 show
lessened symptoms and host lower bacterial populations (1,2) than cvs Ogliarola salentina, Cellina di
Nardò and Kalamata. We are evaluating whether microbial communities inhabiting the xylem vessels
of olive cvs showing different susceptibilities to X. fastidiosa -infection play a role in resistance. To
explore these endophytic microbiomes, a whole-metagenome shotgun analysis is currently ongoing. X.
fastidiosa -infected and healthy olive plants of the cultivars FS17, Leccino and Kalamata, were
selected from the same plot to limit the influence of diverse soil composition and crop management.
Shotgun sequencing of DNA extracted from the xylem tissues will be used to investigate the
microbiome community by bio-informatic analysis. Moreover, efforts to isolate culturable
microorganisms to be used in antagonistic assays against X. fastidiosa, will be performed.
Concurrently, the X. fastidiosa-biocontrol potency of Paraburkholderia phytofirmans PsJN strain,
whose beneficial effects in the reduction of symptoms in Pierce’s Disease (3) have been recently
described, are under evaluation. We are testing the ability of P. phytofirmans to colonise xylem
vessels and interact with X. fastidiosa in tobacco and olive
