Submitted to: Crop Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/11/2009
Publication Date: 7/1/2009
Citation: Hill, C.B., Kim, K., Diers, B.W., Crull, L., Hartman, G.L. 2009. A New Soybean Gene for Resistance to the Soybean Aphid. Crop Science. 49:1193-1200. Interpretive Summary: Since the first discovery of soybean aphid in North America in 2000, the insect has become a major soybean pest. Sources of resistance to soybean aphid have been identified, and one of these sources with a high level of resistance is plant introduction (PI) 200538. The objectives of this research were to determine the inheritance of aphid resistance and to map gene(s) controlling resistance in the PI200538. Segregation among the populations tested indicated that a dominant gene controlled soybean aphid resistance. The resistance gene in PI200538 maps to the same location and is most likely the aphid resistance gene Rag2 that was previously mapped. This information is important to the soybean industry and others that are in need of developing soybean cultivars that have resistance to the soybean aphid.
Technical Abstract: Since the discovery of soybean aphid (Aphis glycines Matsumura) in North America in 2000, the insect has become a major soybean [Glycine max (L.) Merr.] insect pest. Sources of resistance to the soybean aphid have been identified. One of these sources with a high level of resistance is plant introduction (PI) 200538. The objectives of our research were to determine the inheritance of aphid resistance and to map gene(s) controlling resistance in PI200538. PI200538 was crossed with three aphid susceptible genotypes. F2 populations and F2:3 lines developed from these crosses were tested for resistance and with genetic markers. F2 plants from the cross ‘Ina’ x PI200538 segregated 114 resistant to 37 susceptible and F2 plants from the cross ‘Williams 82’ x PI200538 segregated 203 resistant to 65 susceptible when tested for resistance to soybean aphid biotype 1. F2 plants from the cross LD02-4485 x PI 200538 segregated 167 resistant to 62 susceptible when tested for resistance to biotype 2. These populations fit a 3:1 genetic ratio (P=0.89, 0.78, and 0.52, respectively) with resistance dominant over susceptibility. Segregation among F2:3 families from the crosses supported the F2 phenotype analysis that a dominant gene controlled soybean aphid resistance in PI200538. The gene was mapped to soybean linkage group (LG) F and was flanked by the simple sequence repeat (SSR) marker loci Satt510, Soyhsp176, Satt114, and Sct_033 located in the same region as the aphid resistance gene Rag2. Since the resistance gene in PI200538 also gave resistance to soybean aphid biotypes 1 and 2, as does Rag2, it is possible that the gene is Rag2 and not a new aphid resistance gene. Therefore, PI200538 may be an additional source of Rag2.