The endophytic microbiome of X. fastidiosa susceptible and resistant olives

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