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Feeding Plug Formation in Soybean Roots Infected with the Soybean Cyst Nematode. B. Y. Endo, Nematology Laboratory, Plant Protection Institute, U.S. Department of Agriculture, Agricultural Research Service, Beltsville Agricultural Research Center, Northeastern Region, Beltsville, MD 20705; Phytopathology 68:1022-1031. Accepted for publication 30 December 1977. Copyright 1978 The American Phytopathological Society, 3340 Pilot Knob Road, St. Paul, MN 55121. All rights reserved.. DOI: 10.1094/Phyto-68-1022.

The ultrastructure of the early stage of syncytium development in soybean roots attacked by Heterodera glycines was examined to determine the interaction between the host syncytium and the nematode feeding apparatus. One day after inoculation, an electron-dense pluglike deposit was observed between the extended stylet of the nematode and the syncytial wall of the host. During the feeding process, the plug appeared to form a seal between the extended stylet and the cell wall. Four days after inoculation, the plug remained in the opening of the cell wall after the stylet was withdrawn during the normal molting process. The plug apparently has continuity with secretions that appear to flow from the amphidial canals, the openings of the inner labial receptors, and the stylet vestibule. The plug consists of an electron-dense fibrillar mass that forms a structure that may be comprised of nematode secretions and cell wall deposits, both of which are limited by the plasmalemma of the syncytium.