Submitted to: PLOS ONE
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/23/2020
Publication Date: 10/2/2020
Citation: Lee, S.A., Burbank, L.P., Wallis, C.M., Rogers, E.E. 2020. Grapevine phenolic compounds influence cell surface adhesion of Xylella fastidiosa and bind to lipopolysaccharide. PLoS ONE. 15(10):e0240101. https://doi.org/10.1371/journal.pone.0240101.
Interpretive Summary: Many chemical compounds produced by plants are known to influence growth and colonization of bacterial pathogens, either because of antimicrobial activity, or by acting as signals that trigger a pathogen response. Xyella fastidiosa colonizes the xylem tissue of grapevines, an environment that is generally low in nutrients but contains a range of plant-produced compounds classified as phenolics. Specific phenolic compounds found in grapevines were tested for influence on growth and cell-surface attachment of Xylella fastidiosa. Several of these compounds inhibited adhesion of Xylella fastidiosa cells to a solid surface during extended growth, likely due to binding of the compounds to molecules on the outside of the bacterial cell. Identifying plant-produced compounds that can inhibit effective colonization of Xylella fastidiosa in grapevine will improve the ability to identify and screen for novel sources of host resistance.
Technical Abstract: Bacterial phytopathogen Xylella fastidiosa infects a wide range of crops worldwide, including grapevine (Pierce’s Disease). Concentration of secondary plant metabolites found in grape xylem sap, such as phenolic compounds, fluctuate in response to pathogen infection and may be involved in plant defense response. Specific effects of biologically relevant concentrations of phenolic compounds (gallic acid, epicatechin, resveratrol, and coumaric acid) were identified relating to X. fastidiosa cell growth and adhesion dynamics. Several phenolic compounds inhibited cell-surface attachment and reduced expression of fimbrial and afimbrial adhesin genes, but did not inhibit cell growth. These compounds also were depleted from the growth medium by extended bacterial growth, and bound to X. fastidiosa lipopolysaccharide molecules. The role of phenolic compounds in X. fastidiosa cell surface interactions is important in the context of plant colonization and identifying host factors that may increase pathogen resistance. IMPORTANCE: Naturally produced plant phenolic compounds have been identified as potential anti-microbial agents for human pathogenic-bacteria. The effects these compounds have on plant pathogens are less well known but equally important for developing new disease control strategies. Understanding the specific response of Xylella fastidiosa to host plant phenolic compounds will improve the ability to identify and screen for novel sources of host resistance in grapevine.