Submitted to: Crop Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/8/2006
Publication Date: 5/8/2006
Citation: Hill, C.B., Li, Y., Hartman, G.L. 2006. Identification of a single dominant gene for resistance to the soybean aphid in the soybean cultivar Dowling. Crop Science. 46(4):1601-1605
Interpretive Summary: Since its arrival from Asia, the soybean aphid has spread throughout soybean production areas in North America. High aphid populations reduce soybean production directly by causing severe plant damage during feeding, including leaf distortion, stunting, and desiccation. In 2003, extensive economic losses caused by the soybean aphid occurred in soybean in several Midwestern states with an estimated 1.6 million hectares damaged producing a loss of $80 million. Presently, the only means that soybean growers have to control the soybean aphid is with the application of registered insecticides. Plant resistance to the soybean aphid was recently discovered in soybean germplasm. The objective of this study was to determine the pattern of inheritance of the resistance in Dowling. These results indicated that resistance in Dowling was controlled by a single dominant gene that was named Rag1. The monogenic dominant resistance inheritance pattern will enable the rapid introgression of Rag1 into existing cultivars by using back cross breeding procedures to produce new soybean aphid resistant cultivars.
Technical Abstract: A new and serious pest, the soybean aphid (Aphis glycines Matsumara), of soybean, Glycine max (L.) Merr., first found in North America in 2000, rapidly spread throughout the continent, infesting millions of hectares of soybean, and has caused millions of dollars in economic losses. At present, the application of insecticides is the only means to control the soybean aphid; however, genetic resistance to the aphid was recently discovered. The old cultivar "Dowling" was one of the soybean genotypes identified with strong antibiosis-type aphid resistance. The objective of this study was to determine the inheritance of resistance to the soybean aphid in Dowling. Resistance in F1, F2, and F2-derived F3 (F2:3) families produced from crosses between Dowling and the two susceptible soybean cultivars "Loda" and "Williams 82" was analyzed. All F1 plants were resistant to the aphid. Heterogeneity of segregation of F2 plants in 14 Dowling x Loda F2 families was non-significant (P=0.16) and pooled F2 data, with 132 resistant to 45 susceptible plants, fit a 3:1 pattern (P=0.90). Dowling x Williams 82 F2 plants segregated 135 resistant to 44 susceptible plants, also fitting a 3:1 pattern (P=0.89). Segregation among the F2:3 families fit a 1:2:1 monogenic inheritance pattern. These results indicated that resistance in Dowling was controlled by a single dominant gene that was named Rag1. The monogenic dominant resistance inheritance pattern will enable breeders to rapidly introgress Rag1 into existing cultivars by using back cross breeding procedures to produce new soybean aphid resistant cultivars.