Host structural carbohydrate induces vector transmission of a bacterial plant pathogen

• Published in: Proceedings of the National Academy of Sciences - PNAS 2009-12, Vol.106 (52), p.22416-22420
• Main Authors: Killiny, Nabil, Almeida, Rodrigo P.P
• Format: Article
• Language: English
• Subjects: Animals; Bacteria; bacterial proteins; Biological Sciences; Carbohydrates; Carbohydrates - chemistry; Cell adhesion; cell culture; Changes; Culture Media; Data processing; Disease transmission; disease vectors; Expression vectors; Flowers & plants; Gene expression; Gene Expression Profiling; gene expression regulation; Gene regulation; Genes; Genes, Bacterial; Genetic vectors; Genotype & phenotype; Glucans; Glucans - chemistry; Glucans - metabolism; Graphocephala atropunctata; Hemiptera - microbiology; Host plants; Host-Pathogen Interactions - physiology; Insect vectors; Insect Vectors - microbiology; Life history; microarray technology; nutrient availability; Pathogenicity; Pathogens; Pectin; pectins; Pectins - chemistry; Pectins - metabolism; Phenotype; Phenotypes; Plant diseases; Plant Diseases - microbiology; Polysaccharides; Xylella; Xylella - genetics; Xylella - growth & development; Xylella - pathogenicity; Xylella - physiology; Xylella fastidiosa
• ISSN: 0027-8424; 1091-6490
• DOI: 10.1073/pnas.0908562106

Many insect-borne pathogens have complex life histories because they must colonize both hosts and vectors for successful dissemination. In addition, the transition from host to vector environments may require changes in gene expression before the pathogen's departure from the host. Xylella fastidiosa is a xylem-limited plant-pathogenic bacterium transmitted by leafhopper vectors that causes diseases in a number of economically important plants. We hypothesized that factors of host origin, such as plant structural polysaccharides, are important in regulating X. fastidiosa gene expression and mediating vector transmission of this pathogen. The addition of pectin and glucan to a simple defined medium resulted in dramatic changes in X. fastidiosa's phenotype and gene-expression profile. Cells grown in the presence of pectin became more adhesive than in other media tested. In addition, the presence of pectin and glucan in media resulted in significant changes in the expression of several genes previously identified as important for X. fastidiosa's pathogenicity in plants. Furthermore, vector transmission of X. fastidiosa was induced in the presence of both polysaccharides. Our data show that host structural polysaccharides mediate gene regulation in X. fastidiosa, which results in phenotypic changes required for vector transmission. A better understanding of how vector-borne pathogens transition from host to vector, and vice versa, may lead to previously undiscovered disease-control strategies.