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Reactions of Sweet Potato Root Tissue to the Reniform Nematode. Choi -Pheng Yik, Graduate Research Assistant, Department of Plant Pathology and Crop Physiology, USDA, ARS, Louisiana State University, Baton Rouge 70803. Wray Birchfield, Research Plant Pathologist, USDA, ARS, Louisiana State University, Baton Rouge 70803. Plant Dis. 66:707-709. Accepted for publication 3 November 1981. This article is in the public domain and not copyrightable. It may be freely reprinted with customary crediting of the source. The American Phytopathological Society, 1982. DOI: 10.1094/PD-66-707.

Roots of the sweet potato cultivar Centennial were severely infected by the reniform nematode, Rotylenchulus reniformis, 3 wk after they were inoculated in the greenhouse. Histologic sections showed that the nematode penetrated the cortex of the roots and fed in the endodermal layer. A single endodermal cell hypertrophied into a giant cell. The pericycle next to the giant cell reacted severely to infection and hypertrophied into a curved sheet of syncytia. These cells stained darkly with methylene blue, showing dense, granular cytoplasmic contents. Phloem cells at the infection point enlarged, and the cambium and xylem vessels appeared pressed together. Cortical parenchymal cells around the neck of the nematode were also enlarged and irregularly shaped and looked disorganized.