LIPIDS INVESTIGATION IN XYLELLA FASTIDIOSA SUBSP. PAUCA STRAIN DE DONNO LIFESTYLE

Bacteria organize their lipid membrane composition to survive under different environmental conditions. The lipid signals are messengers to modulate motility, biofilm formation and virulence in phytopathogenic bacteria as well as represent a class of signals exchanged during the perception, and regulation of defence mechanism in the host-pathogen interaction. LC-TOF and LC-MS/MS were adopted to assess the lipid composition of X. fastidiosa subsp. pauca strain De Donno and polar, non-polar lipids, free fatty acids and oxylipins were characterized and quantified in bacterial cells and cultural filtrate. The lipid profile of X. fastidiosa subsp. pauca strain De Donno during the interaction with the model plant Nicotiana tabacum Petit Havana SR1 was exploited. This study highlighted specific class of lipids (e.g. ornitholipids and oxylipins) accumulate differently in infected plant tissues compared to uninfected ones. The in vitro and in vivo studies spotlight the following scenario: the lipid profile of X. fastidiosa contributes to shape its lifestyle in vitro during change from twitching motility to biofilm formation and during its relation with the host.  The results suggest the presence of other DSFs than the already described ones (i.e. XfDSF1 and 2), and lipid entities, such as OL1, TAG 52:2, oleic acid and 7,10-diHOME, may constitute an arsenal of molecules that actively contribute to plant-pathogen cross-talk. Moreover, naturally infected and healthy olive samples (cv. Ogliarola salentina) were collected in an affected olive orchard (Lecce and Taranto provinces, Apulia region) to investigate their lipidomic profile. It emerges a scenario in which the X. fastidiosa-infected olive samples presented at least bacterial specific lipid and, other host-pathogen shared lipid entities.