| Abstract: | Breeding soybean [Glycine max (L.) Merr.] cultivars for resistance to soybean cyst nematode (SCN) [Heterodera glycines Ichinohe] is the most efficient means to control this pest. Evaluating and developing new resistance germplasm sources for soybean breeding is very important to prevent SCN from race shifts and provide durable resistance in soybean. We evaluated a newly found germplasm, soybean plant introduction (PI) 89772, which is resistant to SCN Races 1, 2, 3, 5, and moderately resistant to Race 14. The objectives were to identify molecular markers associated with SCN resistance, investigate resistant allelic relationships, and evaluate marker-assisted selection efficiency. The F2 and F2:3 populations were produced by crossing PI 89772 with the susceptible soybean cultivar Hamilton. Thirty-nine restriction fragment length polymorphism (RFLP) and 54 simple sequence repeat (SSR) markers found to be polymorphic were used to anchor loci conferring resistance to SCN Races 1, 2, 3, and 5. Two to three loci were found to give resistance to each SCN race. We found that resistance loci for different races could be anchored within the same region on linkage group (LG) G. A region on LG B1 was also shared by loci providing resistance to SCN Races 1, 2, and 5. Our results indicated that no single locus could provide complete resistance to any one SCN race. The major loci combinations provided high levels of resistance. We conclude that these markers could be highly useful in marker-assisted selection. |