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Physiology and Biochemistry

Relationship of Callose Deposition to Resistance of Lettuce to Plasmopara lactucae-radicis. M. E. Stanghellini, Department of Plant Pathology, University of Arizona, Tucson 85721; S. L. Rasmussen, and G. J. Vandemark. Department of Plant Pathology, University of Arizona, Tucson 85721. Phytopathology 83:1498-1501. Accepted for publication 27 July 1993. Copyright 1993 The American Phytopathological Society. DOI: 10.1094/Phyto-83-1498.

Resistance of lettuce to Plasmopara lactucae-radicis, an obligate root-infecting fungus, was attributed to host deposition of callose around fungal haustoria and production of septumlike intrahyphal callose walls by the fungus. Treatment of a genetically resistant cultivar with 2-deoxy-d-glucose, an inhibitor of callose synthesis by the plant, resulted in susceptibility to the root pathogen. Nutrient deprivation that results from callose deposition may be the basis of resistance of lettuce to the pathogen.

Additional keywords: induced resistance, Pythium.