Xylella fastidiosa subsp. pauca and olive produced lipids moderate the switch adhesive versus non-adhesive state and viceversa

Abstract

Global trade and climate change are reshaping the distribution map of pandemic pathogens. One major emerging concern is Xylella fastidiosa, a tropical bacterium recently introduced into Europe from America. In last decades, X. fastidiosa was detected in several European countries. X. fastidiosa is an insect vector-transmitted bacterial plant pathogen associated with severe diseases in a wide range of hosts. X. fastidiosa through a tight coordination of the adherent biofilm and the planktonic states, invades the host systemically. The planktonic phase is correlated to low cell density and vessel colonization. Increase in cell density triggers a quorum sensing system based on mixture of cis 2-enoic fatty acidsdiffusible signalling factors (DSF) that promote stickiness and biofilm. The lipidome profile of Olea europaea L. (cv. Ogliarola salentina) samples, collected in groves located in infected zones and uninfected zones was performed. The untargeted analysis of the lipid profiles of Olive Quick Decline Syndrome (OQDS) positive (+) and negative (-) plants showed a clustering of OQDS+ plants apart from OQDS-. The targeted lipids profile of plants OQDS+ and OQDS-identified a shortlist of 10 lipids that increase their amount in OQDS+ and X. fastidiosa positive olive trees. These lipid entities, provided to X. fastidiosa subsp. pauca pure culture, impact on the dual phase, e.g. planktonic $ biofilm. This study provides novel insights on OQDS lipid hallmarks and on molecules that might modulate biofilm phase in X. fastidiosa subsp. pauca.

Grapevine phenolic compounds influence cell surface adhesion of Xylella fastidiosa and bind to lipopolysaccharide

“…Not all phenolic compounds present in grapevine xylem sap showed this effect, as coumaric acid did not alter cell attachment or aggregation when present in biologically relevant concentrations. Similar phenotypic changes were seen with olive pathogenic strains of X. fastidiosa exposed to phytochemicals (lipid compounds) present in infected olive tissue, suggesting a broad role of plant produced compounds in progression of disease caused by this pathogen in different host plants [18].…”

“…Similar phenotypic changes were seen with olive pathogenic strains of X . fastidiosa exposed to phytochemicals (lipid compounds) present in infected olive tissue, suggesting a broad role of plant produced compounds in progression of disease caused by this pathogen in different host plants [ 18 ].…”

“…Plants infected with X. fastidiosa had elevated concentrations of calcium, which promoted cell-cell aggregation and biofilm formation, and increased surface adhesion forces [16,17]. In a study conducted in olive trees, several lipid compounds produced by trees infected with X. fastidiosa inhibited biofilm formation and increased planktonic cell growth [18]. Differences in plant chemistry are also associated with X. fastidiosa resistant versus susceptible grapevine and olive varieties [19][20][21].…”

“…In a study conducted in olive trees, several lipid compounds produced by trees infected with X . fastidiosa inhibited biofilm formation and increased planktonic cell growth [ 18 ]. Differences in plant chemistry are also associated with X .…”

Secondary Metabolites in Xylella fastidiosa–Plant Interaction

“…More findings about ionomic differences have emerged, and it has been observed that higher concentrations of calcium (Ca) and manganese (Mn) levels may contribute to protecting against disease caused by Xf infection, as observed previously in the responses of tobacco, grapes, pecans, and blueberries [ 42 , 43 , 44 , 45 ]. Bacterial growth, aggregation, and biofilm formation may be affected by xylem sap components [ 46 ] and by lipid profile [ 47 ], and thus several studies have focused on analyzing xylem-localized small molecules that can potentially inhibit the growth and movement of Xf . Promising in this area was the study conducted on the role of different classes of lipids in the Xf pauca – O. europaea interaction in the modulation of biofilm, their possible use as defense plant signals and finally, as new targets for the development of treatments for OQDS [ 47 ].…”