|YAKABE, L. - US Department Of Agriculture (USDA)|
|PARKER, S. - US Department Of Agriculture (USDA)|
Submitted to: Phytopathology
Publication Type: Abstract Only
Publication Acceptance Date: 6/1/2011
Publication Date: 8/15/2011
Citation: Yakabe, L.E., Parker, S.R., Kluepfel, D.A. 2011. Evaluations and modifications of semi-selective media for improved isolation of Agrobacterium tumefaciens biovar 1 from cultivated walnut. Phytopathology. 101:S196.
Technical Abstract: Agrobacterium tumefaciens, the causal agent of crown gall of walnut, is an aerobic, Gram negative bacterium belonging to the family Rhizobiaceae. Like many in this group, A. tumefaciens is a common inhabitant of soil and plant host tissue. Isolation from these complex environments is difficult even with the use of semi-selective media. Many semi-selective media have been developed for A. tumefaciens and more recent studies of Agrobacterium species have relied on the medium1A. In this study, six previously published semi-selective media were evaluated using a panel of A. tumefaciens biovar 1 and closely related Rhizobiaceae species isolated from walnut orchards in California. Based on the antibiotic and carbon-utilization profiles of twelve A. tumefaciens isolates, D1 and 1A recipes were modified by antibiotic amendment or substitution of the primary carbon source to increase isolation efficiencies and/or selectiveness out of a complex environment. The antibiotics ampicillin, trimethoprim, and vancomycin were evaluated in addition to the carbon sources proline, serine, theonine, and ß-hydroxybutyric acid. Results from these experiments revealed significant variation in isolation efficiency within a genetically diverse group of A. tumefaciens isolates and allowed development of a more selective medium for diagnostics and quantification from soil.