Bacteria associated with Stagonospora (Septoria) nodorum increase pathogenicity of the fungus

In studies with a laboratory isolate of the fungal pathogen Stagonospora (S eptoria) nodorum three different isolates of bacteria were closely associat ed with the fungus. Bacteria were also closely associated with fresh isolat es of S. nodorum obtained from artificially and naturally infected field ma terial. Although a range of bacteria was isolated, only one type of bacteri um was found to be associated with each isolate of S. nodorum. In co-inocul ation studies with pycnidiospores of the fungus on detached leaves, some of the bacterial isolates significantly increased the pathogenicity of the fu ngus, particularly Xanthomonas maltophilia, Sphingobacterium multivorum, En terobacter agglomerans and Erwinia amylovora. Evidence is presented indicat ing that one of the ways that the 'helper bacteria' may assist in the estab lishment of infections is by the production of lipases that were not detect ed in germinating fungal spores.