Southern hybridization of total DNA isolated from cercosporin-degrading (XCZ-3, XAP-50, XAP-75, XAP-1, XAP-39, XAP-49, XAP-34, XAP-31, and XAP-79) and non-cercosporin-degrading (XAP-76, XAV-79, XAV-126, P. syringae pv. tomato DC3000, and P. syringae pv. pisi 209-21-3R) isolates using a PCR-amplified digoxigenin-labeled oxidoreductase gene as a probe. Wild-type strain XCZ-3 was used in lane 1 as a positive control. Sequences homologous to the oxidoreductase are present in all cercosporin-degrading isolates and in the non-cercosporin-degrading isolate P. syringae pv. tomato DC3000.