ARS | Publication request: Association mapping of quantitative resistance to phaeosphaeria nodorum in spring wheat landraces from the USDA National Small Grains Collection

Submitted to: Phytopathology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: June 1, 2011
Publication Date: November 1, 2011
Repository URL: http://riley.nal.usda.gov/nal_web/digi/submission.html
Citation: Adhikari, T., Jackson, E.W., Gurung, S., Hansen, J., Bonman, J.M. 2011. Association mapping of quantitative resistance to phaeosphaeria nodorum in spring wheat landraces from the USDA National Small Grains Collection. Phytopathology. 101(11):1301-1310.

Interpretive Summary: Stagonospora nodorum blotch (SNB) is an important disease of wheat worldwide and developing resistant cultivars is the most economical means of managing the disease. We screened landrace accessions from the USDA-ARS for resistance to the disease and also surveyed the accessions using molecular markers. Landraces are analogous to ‘heirloom’ cultivars. They may contain valuable genes for disease resistance but may also be unsuitable to modern production methods. Using a method known as ‘association analysis’, some previously know genetic regions for SNB resistance were confirmed in the landraces and some new regions discovered. When transferred from the landrace genetic background into more adapted germplasm, such novel resistance should help US plant breeders develop new SNB resistant lines.

Technical Abstract: Stagonospora nodorum blotch (SNB), caused by Phaeosphaeria nodorum (E. Müller) Hedjaroude, is a destructive disease of wheat (Triticum aestivum L.) found throughout the United States. Host resistance is the only economically feasible option for managing the disease; however, few SNB resistant wheat cultivars are known to exist. In this study, we report findings from an association mapping (AM) study of SNB resistance in 567 spring wheat landraces of diverse geographic origin. The accessions were evaluated for seedling resistance to SNB in a greenhouse, and phenotypic data were analyzed with 747 polymorphic diversity array technology (DArT)® markers. Association analysis indicated that nine DArT markers on five chromosomes (2D, 3B, 5B, 6A, and 7A) were significantly associated with resistance to SNB. Genetic regions on 2D and 5B correspond to previously mapped quantitative trait loci (QTL) conferring resistance to SNB whereas the remaining QTL appeared to be novel. These results demonstrate that the use of AM is an effective method for identifying new genomic regions associated with resistance to SNB in spring wheat landraces. Additionally, the novel resistance found in this study could be useful in wheat breeding aimed at controlling SNB in the United States