DOCUMENTATION AND CHARACTERIZATION OF XYLELLA FASTIDIOSA STRAINS IN LANDSCAPE HOSTS

• Author(s): Cooksey, Donald; Costa, Heather; Wong, Frank; Downer, James; Henry, Mike; Kabashima, John; Karlik, John; LeStrange, Michelle; Shaw, David;
• Abstract: To better understand the impact of Xylella fastidiosa on the urban environment and the potential for ornamental hosts to serve as reservoirs for agronomically important diseases caused by the bacteria, a survey project was initiated to document and characterize strains of the bacteria harbored in landscape plants. Targeted sampling of 122 landscape species either symptomatic for bacterial scorch or testing positive for X. fastidiosa by ELISA in 2003 was performed. Of the 830 samples, 321 tested positive by ELISA (representing 77 of the 122 species tested). X. fastidiosa was also detected in 23 species by PCR-amplification using X. fastidiosa specific primers. Twenty-seven isolates from 13 host species were obtained from samples testing positive by ELISA. Isolates from plants not previously reported as hosts in southern California urban environments included mulberry, heavenly bamboo, magnolia, day lily, western redbud, jacaranda and peach. Genetic characterization of these isolates by 16S-23S rDNA sequencing distributed these isolates amongst previously characterized strain groups: almond leaf scorch (crape myrtle, ornamental plum, liquidambar, gingko, olive), Pierces disease (magnolia, peach, western redbud), mulberry leaf scorch (mulberry, heavenly bamboo), and oleander leaf scorch (magnolia, jacaranda, day lily). The role of some X. fastidiosa strains in their ability to cause disease is presently being tested by fulfilling Kochs postulates in glasshouse experiments. The data collected from this study strongly suggest that X. fastidiosa is causing a number of scorch diseases in the urban landscape, and that strains of agronomic importance may be harbored in this environment.
• Publication Date: Dec 2004
• Journal: 2004 Pierce's Disease Research Symposium