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Lignification of Lesion Borders in Rhizoctonia-Infected Bean Hypocotyls. Virginia Stockwell, Department of Plant Pathology, Colorado State University, Fort Collins 80523; Penelope Hanchey, Department of Weed Science, Colorado State University, Fort Collins 80523. Phytopathology 77:589-593. Accepted for publication 6 October 1986. Copyright 1987 The American Phytopathological Society. DOI: 10.1094/Phyto-77-589.

Lesions formed on bean (Phaseolus vulgaris L., ‘Red Kidney’) hypocotyls infected with Rhizoctonia solani are surrounded by autofluorescent cell walls resistant to maceration by cell wall-degrading enzymes. These lesion border cell walls stained positively for lignin and phenols. Lesion border walls were macerated by a mixture of cellulase and macerase after delignification, but not after extraction of calcium or fats and waxes. Peroxidase and polyphenoloxidase were active in young lesions in advance of fungal hyphae. Results suggest that lignification of cell walls may be an important factor in limiting lesion expansion in stem canker of beans.

Additional keywords: resistance.