INHERITANCE OF 3 STEARIC-ACID MUTANTS OF SOYBEAN

Resistance to soybean cyst nematode (SCN) Heterodera glycines Ichinohe has been derived from only a few soybean (Glycine max L., Merr.) lines resulting in a narrow genetic base for SCN resistance in the commerical cultivars. Screening of the soybean germplasm has resulted in the detection of additional sources of resistance. Ten soybean plant introductions (PI lines) were evaluated for reaction to races 3, 4, and 5 and SCN. The screening was done in the greenhouse by inoculating with 1000 eggs of SCN and counting the white females (cysts) on the roots after 30 days. Of the 10 lines, seven were resistant to race 3, two were resistant to race 4, and four were resistant to race 5. One line, PI 437654 was resistant to all three races. This PI line is a possible source of resistance to races 3, 4, and 5 of SCN, and may be genetically different from other sources of resistance previously reported.