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Molecular Plant Pathology

Take-All Suppressive Properties of Bacterial Mutants Affected in Antibiosis. Alan R. Poplawsky, Postdoctoral research associate, Department of Plant Pathology, University of Wisconsin, Madison 53706, Present address: Department of Plant, Soil and Entomological Sciences, University of Idaho, Moscow 83843-4196; Albert H. Ellingboe, Professor, Department of Plant Pathology, University of Wisconsin, Madison 53706. Phytopathology 79:143-146. Accepted for publication 4 August 1988. Copyright 1989 The American Phytopathological Society. DOI: 10.1094/Phyto-79-143.

Ten Tn5-induced mutants of bacterial strains I11 and NRRL B-15135 with altered inhibition (antibiosis) of Gaeumannomyces graminis var. tritici on agar medium were added to fungal inoculum by vacuum infiltration and tested for their ability to suppress take-all disease. Eight mutants were antibiosis-negative and two mutants gave increased antibiosis. Suppression was evaluated by measuring the weight of plant tops and estimating the level of root infection. In all experiments, all four NRRL B-15135 antibiosis-negative mutants showed lower levels of disease suppression when compared with the parent strain. This was also true with three of the four I11 antibiosis-negative mutants, except in one experiment where, although two of these mutants induced significantly lower plant top weights than those induced by the parent, root infection was not significantly greater. The suppressive properties of the fourth I11 mutant were not significantly different from the parent. The two NRRL B-15135 mutants with increased antibiosis towards the pathogen did not give increased levels of disease suppression.