Submitted to: Crop Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/27/2001
Publication Date: N/A
Citation: Interpretive Summary: Durum wheat is an excellent source of Hessian fly resistance genes. However, the transfer of genetic traits, such as pest resistance, from durum to common wheat requires more time and effort than that required transferring traits between common wheat sources. Thus, methods that reduce the time required identifying durum sources with the greatest potential for resistance are extremely important. Following initial screening trials with laboratory-reared flies, in which resistance sources are identified, seed of promising wheat lines is in limited supply. However, small increases can be readily made to enable further limited testing to identify sources with greatest potential. It is critical at this stage of evaluation, however, that tests be conducted with Hessian fly sources that provide the broadest possible range of genetic diversity (i.e., resistance-breaking genes) and are representative of current field populations, in order to enhance the selection process. Twenty-six durum wheat lines were tested against fly populations from mid-Atlantic and southeastern states that represented a broad range in genetic diversity for resistance breaking biotypes. Twenty-four lines demonstrated excellent resistance to all populations and hold considerable promise as sources of resistance for use in wheat breeding programs throughout the eastern US. The number of resistance genes carried by the lines varied from one to three, but all lines were equally effective regardless of gene number. Lines with single genes can be most readily utilized in breeding efforts. Seed of the 24 lines was made available to university and commercial breeders in 2001.
Technical Abstract: Damage from Hessian fly, Mayetiola destructor (Say), infestation of soft red winter wheat, Triticum aestivum L em Thell., in eastern USA has been reduced by the deployment of genes for resistance in commercial cultivars. Recently Hessian fly populations in the eastern USA have developed virulences to previously deployed genes for resistance except for H13, deployed in 1998. Durum wheat, Triticum durum desf., is an important source of resistance to Hessian fly. We selected four populations of Hessian fly, believed representative of eastern USA, for seedling tests of 26 durum genotypes, which had shown resistance to Hessian fly laboratory biotypes B, D or L in earlier seedling tests. We determined the putative number of genes conditioning resistance to laboratory biotype L in backcross segregation analysis of 11 PI selections for which we had no information. We also recorded the number of genes for resistance to Hessian fly of other durum genotypes in the test from observed segregation or published data. Some common wheat genotypes were included in tests with the four populations. Most of the 26 durum genotypes were resistant to the four eastern USA Hessian fly populations. The four Hessian fly populations were similar in avirulence to most durum germplasm lines but exhibited virulence to a few lines. The four populations were virulent to the previously deployed resistances provided by H3, H5 and H6. The northern two Hessian fly populations were virulent and the southern two populations were avirulent to the previously deployed resistance of H7H8. Resistance to laboratory biotypes D or L of the 26 durum genotypes was conditioned by one, two or three genes depending upon the line.