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Title: Interactions between Grape and Sweet Orange Strains of Xylella Fastidiosa in Colonization and Symptom Production in Periwinkle Plants

Author
item Hasegawa, Hiroaki
item Hartung, John

Submitted to: BARC Poster Day
Publication Type: Abstract Only
Publication Acceptance Date: 4/20/2007
Publication Date: 4/20/2007
Citation: Hasegawa, H., Hartung, J.S. 2006. Interactions between Grape and Sweet Orange Strains of Xylella Fastidiosa in Colonization and Symptom Production in Periwinkle Plants. BARC Poster Day.

Interpretive Summary:

Technical Abstract: Xylella fastidiosa is one of the most economically important bacterial plant pathogens, causing serious diseases including citrus variegated chlorosis in Brazil and Pierce’s disease of grape in California. The sweet orange strain of X. fastidiosa is a particular a threat to US citrus industry and it has been designated as a select agent. What would happen if the sweet orange strain of Xylella fastidiosa arrived in California? Periwinkle plants are a convenient plant host for both pathogens. To understand interactions between grape and citrus strains of X. fastidiosa in planta, we inoculated X. fastidiosa strain Temecula1 (grape) and strain 9a5c (citrus) together as well as separately into periwinkle, and monitored plant colonization and population sizes by using real-time PCR techniques. Here, we show preliminary evidence that there is a positive interaction between X. fastidiosa strains from citrus and grape. These strains colonized more rapidly and developed higher population densities when both strains were present in the same host plants, as compared to when either strain was inoculated alone. Chlorosis-like symptoms were produced on the leaves of plants when both strains were present whereas single strain inoculations failed to produce symptoms. Our findings demonstrate the possible positive interactions between X. fastidiosa citrus and grape strains in planta.