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Resistance

Effect of Host on Multiplication and Distribution of Bean Common Blight Bacteria. C. R. Cafati, Former Rockefeller graduate fellow, Department of Botany and Plant Pathology, Michigan State University, East Lansing, 48824, Present address of senior author: INIA, Casilla 5427, Santiago, Chile; A. W. Saettler, research plant pathologist, Edible Legumes, Agricultural Research, Science and Education Administration, U.S. Department of Agriculture, Michigan State University, East Lansing, 48824. Phytopathology 70:675-679. Accepted for publication 13 December 1979. This article is in the public domain and not copyrightable. It may be freely reprinted with customary crediting of the source. The American Phytopathological Society, 1980. DOI: 10.1094/Phyto-70-675.

Populations of rifampin-resistant Xanthomonas phaseoli (= X. campestris) (Xp) were determined in and on leaves and pods of resistant (tepary bean [Phaseolus acutifolius]), moderately resistant (breeding line MSU-51319 and Great Northern-type cultivar Valley [both P. vulgaris]) and susceptible bean hosts (cultivars Seafarer and Tuscola [both P. vulgaris]) by using a rifampin-containing medium. While bacterial multiplication patterns were similar for leaves and pods of moderately resistant and susceptible cultivars, maximum bacterial populations were generally lower in the former, particularly during the reproductive stage of plant development. High Xp populations were detected in and on uninoculated, symptom-free leaves of both susceptible and moderately resistant hosts, but not in or on those of resistant genotypes. Systemic colonization of plants by Xp throughout the growing season was greatest in the susceptible genotypes, intermediate in the moderately resistant genotypes, and absent in the resistant genotype.