|Gent, David - Dave
|TOWNSEND, M - Oregon State University
|TWOMEY, MEGAN - Oregon State University
|HILL, STEVEN - Oregon State University
|HENDRIX, DAVID - Oregon State University
Submitted to: Euphytica
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/31/2016
Publication Date: 3/28/2017
Citation: Henning, J.A., Gent, D.H., Townsend, M.S., Twomey, M., Hill, S.T., Hendrix, D. 2017. QTL analysis of resistance to powdery mildew in Hop (Humulus lupulus L.). Euphytica. 213:98. doi: 10.1007/s10681-017-1849-9.
Interpretive Summary: Hop powdery mildew (HPM) causes significant annual losses due to yield reduction as well as quality. USDA-ARS scientists along with collaborators at Oregon State University performed a study to identify markers that will ultimately be used to select for lines possessing long-term resistance to HPM. Fifteen molecular markers were identified that were linked to resistance. Some of these markers are linked to genes thought to have activity in plant disease resistance in other crop species. These markers are in the process of being validated for use in breeding programs. Once validated on a wide range of hop lines, breeders can utilize markers in the seedling stage—accelerating the breeding process as well as increasing selection accuracy, while reducing nursery costs by growth of only resistant lines.
Technical Abstract: Powdery mildew infection of hop results in significant production losses on an annual basis by reducing yields as well as cone quality. One of the best means to increase yield and quality is the production of resistant hop lines. Breeding for resistance can be significantly improved and accelerated by use of marker-assisted selection. The objective of this preliminary study was to identify markers linked with genetic resistance to hop powdery mildew (HPM). A genetic map with 2263 markers was developed with 10 linkage groups. Composite interval mapping (CIM) identified three highly significant markers, all located on linkage group 6. Mixed linear models (MLM) identified 15 markers associated with expression of resistance to HPM. Three of the 15 markers identified using MLM were also identified in CIM analysis. Evaluation of the scaffolds containing the significant markers identified seven putative genes—several of which appear to have disease resistant functions in other plant species. The markers identified in this study still require validation in unrelated populations prior to implementation in breeding programs.