Submitted to: American Society for Microbiology
Publication Type: Abstract Only
Publication Acceptance Date: 5/10/2004
Publication Date: 10/1/2004
Citation: Goradia, L., Hartman, G.L., Daniel, S.L. 2004. Pathogenicity of xanthomonas axonopodis pv. glycines, the causative agent of bacterial pustule in soyeans. American Society for Microbiology.
Technical Abstract: Xanthomonas axonopodis pv. glycines is the casual agent of bacterial pustule of soybean (Glycine max [L.] Merr). Bacterial pustule is a prevalent disease in many soybean-growing areas, especially in countries such as Brazil, China and India where it can cause yield losses of up to 40%. X. axonopodis pv. glycines is spread by wind-blown rain and can survive in crop debris and seeds. This pathogen infects through stomata and wounds on soybean leaves and causes hypertrophy of host cells. The goals of this study were to compare strains of X. axonopodis pv. glycines at the metabolic, molecular, and pathogenic levels and to screen a wide variety of Roundup Ready soybean cultivars for resistance to X. axonopodis pv. glycines. Strains of X. axonopodis pv. glycines were isolated from infected soybean leaves collected from soybean fields at the University of Illinois (UIUC-1 and UIUC-2), and were obtained from the American Type Culture Collection (ATCC 17915) and the University of Florida (UF). All four strains grew well in potato dextrose broth at 25C. Metabolic fingerprinting (using Biolog microarray-based technology), sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) of cell proteins, and pathogenicity testing determined with a greenhouse assay were used to compare strains. Metabolic fingerprinting (based on the number of different carbonaceous substrates that were able to support growth) showed that the UIUC-1 was different than the other three strains. SDS-PAGE analysis revealed only minor differences in protein profiles among these strains. The greenhouse assay indicated that UIUC-1 was more aggressive on susceptible soybeans and produced more pustules than the other strains. Greenhouse tests also demonstrated that 146 (~28%) of the 525 Roundup Ready soybean cultivars screened were susceptible to UIUC-1 and developed pustules. These results suggest that resistance to bacterial pustule is not being maintained in some commercial soybean varieties and that the potential exists for X. axonopodis pv. glycines to emerge as a major soybean pathogen in the USA, resulting in significant reductions in soybean yields.