Identification of Rathayibacter rathayi in Oregon and Maryland

Most bacteria in the genus Rathayibacter, are carried by Anguina nematodes and cause gummosis in grasses and cereals. R. toxicus produces lethal animal toxins in fodder grasses in Australia and Africa. R. tritici is officially regulated in the USA and some other wheat-growing countries. Bacterial gummosis in orchardgrass (Dactylis glomerata) is problematic for seed production in Oregon, with up to 5% heads affected in 2003. The causal organism was identified only as Rathayibacter sp. Several slow-growing yellow-pigmented. Gram-positive bacteria were isolated from affected plants from Oregon and Maryland. DNA was extracted for reassociation studies, AFLP analysis and partial ITS sequencing. The new strains shared more than 70% DNA relatedness with R. rathayi but less than 70% with R. tritici or R. toxicus. The AFLP pattern closely matched that of R. rathayi and the ITS sequence was identical. This is the first confirmation of R. rathayi in Oregon and Maryland.