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Influence of Heterodera glycines on Leghemoglobins of Soybean Nodules. Jeng- sheng Huang, Associate professor, Department of Plant Pathology, North Carolina State University, Raleigh 27650; Kenneth R. Barker, professor, Department of Plant Pathology, North Carolina State University, Raleigh 27650. Phytopathology 73:1002-1004. Accepted for publication 8 February 1983. Copyright 1983 The American Phytopathological Society. DOI: 10.1094/Phyto-73-1002.

Four- to five-day-old soybean seedlings were dipped in a suspension containing 109 colony-forming units of Rhizobium japonicum and transplanted, seven per 20-cm-diameter clay pot containing a soil:sand (1:1, v/v) mixture. Three days after transplanting, some pots were inoculated with 2,500 juveniles of race 1 of Heterodera glycines per plant; other uninoculated pots served as controls. Plants were harvested 5 wk after nematode inoculation. Nodules harvested from nematode-infected soybeans had lower fresh weights per plant and lower specific nitrogenase activity (micromoles of C2H4 formed per gram of nodules per hour) as assayed by the acetylene reduction procedure. Leghemoglobins (Lb) were extracted from soybean nodules, purified in a Sephadex G-15 column, and separated into four components, Lba, Lbb, Lbc, and Lbd by DEAE-cellulose column chromatography. Leghemoglobin content per gram of nodule was lower in nematode-infected soybeans than in the nodules of control plants. Lba from nematode-infected and control plants had similar ultraviolet and visible light spectra and gel electrophoresis profiles, as did the Lbb, Lbc, and Lbd. The ratio of Lbc/Lba, however, was higher from nematode-infected soybeans than from control plants. The significance of this difference is discussed.

Additional keywords: Glycine max, nitrogen fixation, soybean cyst nematode.