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Differences in Anatomy, Plant-Extracts, and Movement of Bacteria in Plants of Bacterial Wilt Resistant and Susceptible Varieties of Alfalfa. Y. S. Cho, Former Research Assistant, now Assistant Professor, Seoul National University, Suwon, Korea; R. D. Wilcoxson(2), and F. I. Frosheiser(3). (2)Professor, Department of Plant Pathology, University of Minnesota; (3)Research Plant Pathologist, Plant Science Research Division, ARS, USDA, St. Paul, Minnesota 55101. Phytopathology 63:760-765. Accepted for publication 27 December 1972. DOI: 10.1094/Phyto-63-760.

Roots and stems of plants of alfalfa (Medicago sativa) varieties resistant to bacterial wilt caused by Corynebacterium insidiosum, had fewer vascular bundles, shorter vessel elements, and a thicker cortex than those of plants of susceptible varieties. The number of vessel elements present in vascular bundles, the shape of vessel elements in cross section, and the compactness of xylem cells were not correlated with resistance to wilt. The pathogen grew less profusely in crude aqueous extracts from roots or whole plants, from resistant varieties. Bacteria sprayed onto wounded cotyledons entered and moved more rapidly through plants of susceptible than resistant varieties.