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High Contrast Resolution of the Mycelia of Pathogenic Fungi in Corn Tissue After Staining with Calcofluor and Destaining with Cellulase. A. T. Trese, Department of Plant Pathology, University of Missouri, Columbia 65211; D. C. Loschke, Department of Plant Pathology, University of Florida, Gainesville 32611. Phytopathology 80:196-200. Accepted for publication 29 August 1989. Copyright 1990 The American Phytopathological Society.. DOI: 10.1094/Phyto-80-196.

We have improved on a novel staining technique to monitor fungal growth in corn inoculated with Exserohilum turcicum, Bipolaris maydis, or Bipolaris zeicola. Infected leaf pieces are overstained with Calcofluor until both host cells and fungal mycelia fluoresce brightly. This is followed by selective destaining of the plant cell walls with the enzyme cellulase. The resulting high contrast resolution of fungal mycelia allows thorough examination of infection sites in all three host-pathogen combinations. Using this method, we measured fungal growth in monogenically resistant corn isolines inoculated with two races of E. turcicum. Fungal growth in compatible and incompatible interactions is similar 3 days after infection, indicating that resistance is not yet cytologically apparent.