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Synthesis of Nucleic Acids at Infection Sites of Soybean Roots Parasitized by Heterodera glycines. Burton Y. Endo, Nematologist, Crops Research Division, ARS, USDA, Beltsville, Maryland 20705; Phytopathology 61:395-399. Accepted for publication 13 November 1970. DOI: 10.1094/Phyto-61-395.

Syncytia induced in soybean roots by the soybean cyst nematode are characterized by the presence of numerous enlarged nuclei in a mass of dense cytoplasm. Observations of infected root sections made during various stages of nematode development show that syncytial nuclei are relatively quiescent in terms of deoxyribonucleic acid (DNA) synthesis. However, tritiated thymidine was incorporated in nuclei of syncytia located in both the cortical and vascular regions of infected roots. A primary site of DNA synthesis in a developing syncytium was at the leading edge of the syncytium. Nuclei of cells in this transitional zone showed high 3H-methylthymidine uptake, signifying sites of active DNA synthesis.