Location: Cereal Crops ResearchTitle: Biotype differences for resistance to Russian wheat aphid in barley) Author
Submitted to: Crop Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/22/2014
Publication Date: 7/1/2014
Publication URL: http://handle.nal.usda.gov/10113/59039
Citation: Dahleen, L.S., Mornhinweg, D., Bregitzer, P., Vitou, J., Cakir, M. 2014. Biotype differences for resistance to Russian wheat aphid in barley. Crop Science. 54:1505-1513. Interpretive Summary: Russian wheat aphid (RWA) is an insect that attacks barley and wheat, reducing seed yield and quality. Barley lines that are resistant to the RWA present in the US are available, but new RWA types or biotypes in the US do attack different wheat varieties. In this study, we examined the reaction of barley to four RWA biotypes from different countries compared to the main US biotype and used molecular markers to locate the position of genes that provide resistance to these other biotypes. We found that 23 lines that were resistant to the main US RWA biotype also were resistant to RWA biotypes from Hungary, Chile, Mexico, and Iran. Genes that had large effects on resistance to biotypes from Hungary and Chile were located, but only genes with small effects were found for resistance to RWA from Mexico and Iran. The 23 lines with resistance to all the biotypes will be a good starting point for breeding barley varieties with resistance to multiple RWA biotypes.
Technical Abstract: Russian wheat aphid (RWA) is a worldwide insect pest of barley, causing crop losses each year. Previously identified resistant barley lines do not show variable reactions to the eight USA RWA biotypes identified by wheat reactions. However, additional RWA isolates have been identified outside the USA. The objective of this research was to determine whether additional RWA biotypes exist that impact resistance in barley, and whether resistance to these biotypes is present in the resistant barley germplasm and cultivars that have been developed by the USDA-ARS. A total of 166 barley lines were rated for chlorosis and leaf rolling in response to infestation with RWA USA biotype 1, and to individual isolates from Hungary, Chile, Mexico, and Iran. Each barley line was genotyped for 5912 SNP markers and the combined data used for association mapping of loci associated with resistance to each RWA isolate. A total of 40 loci were associated with resistance to the five RWA isolates. Biotype differences were evident, with only 23 lines showing resistance to all five biotypes. Loci with large effects on mean chlorosis and rolling differences were found for resistance to biotypes from the USA, Hungary, and Chile, while the loci for resistance to biotypes from Mexico and Iran had small effects on these traits, which may pose problems for developing resistant germplasm. The 23 lines resistant to all biotypes included 10 unadapted germplasm accessions and 13 improved germplasm lines, and provide useful germplasm for developing new barley cultivars with resistance to multiple RWA biotypes.