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Cytology and Histology

Histopathology of Sweet Corn Seed and Plants Infected with Fusarium moniliforme and F. oxysporum. Ellen Briskin Lawrence, Graduate student, Fusarium Research Center, Department of Plant Pathology, The Pennsylvania State University, University Park 16802; Paul E. Nelson(2), and J. E. Ayers(3). (2)(3)Professors, Fusarium Research Center, Department of Plant Pathology, The Pennsylvania State University, University Park 16802. Phytopathology 71:379-386. Accepted for publication 2 September 1980. Copyright 1981 The American Phytopathological Society. DOI: 10.1094/Phyto-71-379.

Hyphae of Fusarium moniliforme were not found in stained and sectioned kernels of two sweet corn inbred lines. However, spherical to amorphous bodies occurred throughout the parenchymatous tip cap tissue and occasionally in the endosperm between the tip cap and the embryo. The fungus grew rapidly through the root system and crown of greenhouse-grown plants but made little additional growth until anthesis, when the rest of the plant including the cob and kernels was colonized rapidly. The root or mesocotyl epidermis was penetrated either directly or through wounds. The outer cortical layers collapsed and intercellular materials and globular bodies were present prior to fungal invasion. Hyphae were mainly intercellular and eventually penetrated throughout the tissues. In the stem, protoxylem vessel elements became occluded, intercellular material accumulated in the parenchyma, parenchyma cells around vascular bundles collapsed, and hyphae penetrated throughout the cells. Occluded xylem vessel elements also occurred in the leaf and shank. Mycelium was evident in the outer edge of the cob. Tissues of the floret or the fertilized ovary, or both, collapsed. Globular bodies were found throughout the infected tissue.