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United States Department of Agriculture

Agricultural Research Service

Research Project: ECOLOGICALLY BASED PEST MANAGEMENT IN MODERN CROPPING SYSTEMS

Location: North Central Agricultural Research Laboratory

Title: Performance and prospects of Rag genes for management of soybean aphid

Authors
item HESLER, LOUIS
item Chiozza, Mariana -
item O'Neal, Matthew -
item Macintosh, Gustavo -
item Tilmon, Kelley -
item Chandrasena, Desmi -
item Tinsley, Nicholas -
item Cianzio, Silvia -
item Costamagna, Alejandro -
item Cullen, Eileen -
item Difonzo, Christina -
item Potter, Bruce -
item Ragsdale, David -
item Steffey, Kevin -
item Koehler, Kenneth -

Submitted to: Entomologia Experimentalis et Applicata
Publication Type: Review Article
Publication Acceptance Date: March 27, 2013
Publication Date: May 28, 2013
Citation: Hesler, L.S., Chiozza, M.V., O'Neal, M.E., Macintosh, G.C., Tilmon, K.J., Chandrasena, D.I., Tinsley, N.A., Cianzio, S.R., Costamagna, A.C., Cullen, E., Difonzo, C.D., Potter, B.D., Ragsdale, D.W., Steffey, K., Koehler, K.J. 2013. Performance and prospects of Rag genes for management of soybean aphid. Entomologia Experimentalis et Applicata. 147(3):201-216. doi:10.1111/eea.12073.

Interpretive Summary: The soybean aphid is a relatively new insect pest of soybean in North America, and its infestations have led to extensive insecticide use in northern soybean-growing regions there. Host-plant resistance is one possible means of managing soybean aphid in lieu of insecticides. Various Rag genes that confer aphid resistance in soybean have been recently identified, and field-testing and commercial release of resistant soybean lines have followed. In this paper, we review results of field tests with Rag-containing soybean lines in North America, then present results from a coordinated regional test across several field sites in the north-central USA using single-gene Rag lines, and finally discuss prospects for use of Rag genes to manage soybean aphids. Field tests conducted independently at multiple sites showed that soybean-aphid populations peaked in late summer on lines with Rag1 or Rag2 and reached levels on susceptible lines that could cause economic yield loss, whereas lines with a combination of Rag1 + Rag2 held soybean-aphid populations below economic levels. In the regional test, aphid populations were generally kept in check by lines containing one of the Rag genes. Aphids occasionally reached putative economic levels on Rag1 lines for some site-years, but yield loss was moderated on those lines, indicating that Rag1 may confer additional, unexpected performance traits to soybean. Moreover, no yield penalty has been found for lines with Rag1, Rag2, or Rag1 + Rag2 combinations in the absence of significant aphid infestation. Results suggest that use of aphid-resistant soybean lines with Rag genes may be viable for managing soybean aphids. However, strains of soybean aphid that can thrive on soybean despite the presence of Rag genes were identified before release of aphid-resistant soybean, and thus a strategy for optimal deployment of aphid-resistant soybean is needed to ensure long-term use of this technology in light of these strains.

Technical Abstract: The soybean aphid, Aphis glycines Matsumura, is an invasive insect pest of soybean [Glycine max (L.) Merr.] in North America, and it has led to extensive insecticide use in northern soybean-growing regions there. Host-plant resistance is one potential alternative strategy for managing soybean aphid. Several Rag genes that show antibiosis and antixenosis to soybean aphid have been recently identified in soybean, and field-testing and commercial release of resistant soybean lines has followed. In this paper, we review results of field tests with soybean lines containing Rag genes in North America, then present results from a coordinated regional test across several field sites in the north-central USA, and finally discuss prospects for use of Rag genes to manage soybean aphids. Field tests conducted independently at multiple sites showed that soybean-aphid populations peaked in late summer on lines with Rag1 or Rag2 and reached economically injurious levels on susceptible lines, whereas lines with a pyramid of Rag1 + Rag2 held soybean-aphid populations below economic levels. In the regional test, aphid populations were generally suppressed by lines containing one of the Rag genes. Aphids occasionally reached putative economic levels on Rag1 lines for some site-years, but yield loss was moderated on those lines, indicating that Rag1 may confer tolerance to soybean aphid in addition to antibiosis and antixenosis. Moreover, no yield penalty has been found for lines with Rag1, Rag2, or pyramids. Results suggest that use of aphid-resistant soybean lines with Rag genes may be viable for managing soybean aphids. However, virulent biotypes of soybean aphid were identified before release of aphid-resistant soybean, and thus a strategy for optimal deployment of aphid-resistant soybean is needed to ensure sustainability of this technology.

Last Modified: 9/10/2014