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Precision QTL mapping of downy mildew resistance in hop (Humulus lupulus L.)

ScholarsArchive at Oregon State University

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Title Precision QTL mapping of downy mildew resistance in hop (Humulus lupulus L.)
Names Henning, J. A. (creator)
Gent, D. H. (creator)
Twomey, M. C. (creator)
Townsend, M. S. (creator)
Pitra, N. J. (creator)
Matthews, P. D. (creator)
Date Issued 2015-04 (iso8601)
Note To the best of our knowledge, one or more authors of this paper were federal employees when contributing to this work. This is the publisher’s final pdf. The published article is copyrighted by Springer and can be found at: http://link.springer.com/journal/10681. Supporting Information can be found at: http://link.springer.com/article/10.1007%2Fs10681-015-1356-9.
Abstract Hop downy mildew (DM) is an obligate
parasite causing severe losses in hop if not controlled.
Resistance to this pathogen is a primary goal for hop
breeding programs. The objective of this study was to
identify QTLs linked to DM resistance. Next-generation-sequencing was performed on a mapping population
segregating for DM resistance levels. Cloned
plants were grown in a RCBD with three replicates
under three environments: greenhouse (GH), field
plots in Oregon (OR), Corvallis field plots in Washington
(WA), Yakima). The linkage map of 3,341 SNP
markers was determined with a four-stage process
using Rqtl, TMAP, Joinmap v 4.0 and MERGEMAP.
QTL analysis was performed using JMP Genomics
and TASSEL 5.0. SNP markers were distributed
across 11 linkage groups (LGs) with an average
distance between markers of 0.2 cM and total distance
of 745.9 cM. QTLs for all three environments were
identified using multiple interval mapping. Overall
heritability across the three environments varied from
h² = 0.38 (GH) to 0.57 (OR). A total of 22 QTLs
across 8 LG were identified for DM resistance: 5
identified from OR field data, 12 using WA data and
five from GH DM data. No epistasis was observed.
This study points out the complexity of genetic control
of DM resistance in hop and identifies several markers
that can be potentially be used to select for DM
resistance in hop. It also provides the first linkage map
suitable for genome sequencing due to the high density
of SNP markers.
Genre Article
Topic Downy mildew
Identifier Henning, J. A., Gent, D. H., Twomey, M. C., Townsend, M. S., Pitra, N. J., & Matthews, P. D. (2015). Precision QTL mapping of downy mildew resistance in hop (Humulus lupulus L.). Euphytica, 202(3), 487-498. doi:10.1007/s10681-015-1356-9

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