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Cytology and Histology

Morphological Characteristics of Syncytia in Susceptible Hosts Infected by the Soybean Cyst Nematode. Y. H. Kim, Former graduate assistant, Department of Plant Pathology, University of Arkansas, Fayetteville 72701; K. S. Kim(2), and R. D. Riggs(3). (2)(3)Professors, Department of Plant Pathology, University of Arkansas, Fayetteville 72701. Phytopathology 76:913-917. Accepted for publication 21 March 1986. Copyright 1986 The American Phytopathological Society. DOI: 10.1094/Phyto-76-913.

Morphological characteristics of syncytia induced by Heterodera glycines (race 3) were compared in soybean, cleome, and ‘Kobe' lespedeza. The syncytia formed in cleome were confined to the stele, where they replaced large regions of the vascular bundle. The nematode penetrated into the vascular bundle to initiate and feed on these syncytia. Syncytia in lespedeza were initiated in the inner cortical region, then developed centripetally ultimately to involve the phloem and xylem with only a small part of the vascular bundle invaded by syncytia. The nematodes that fed on such syncytia were located in the cortex. In soybean, syncytia were formed inside or outside the stele or both. The major characteristic features of syncytia, such as cell-wall perforation and hypertrophy of syncytium component cells, were similar among the various host plants. However, the cell-wall ingrowths, another characteristic of syncytia, were more prominent in soybean than in lespedeza, and much more than in cleome.