Sammendrag
Barley net blotch caused by the necrotrophic fungus Pyrenophora teres is a major barley
disease in Norway. It can cause grain shriveling and yield losses, and resistance in currently
grown cultivars is insufficient. In this study, a set of 589 polymorphic SNP markers was used
to map resistance loci in a population of 109 doubled haploid lines from a cross between the
closely related Norwegian cultivars Arve (moderately susceptible) and Lavrans (moderately
resistant). Resistance to three net form net blotch (P. teres f. teres) single spore isolates
was evaluated at the seedling stage in the greenhouse and at the adult plant stage under
field conditions during three years. Days to heading and plant height were scored to assess
their influence on disease severity. At the seedling stage, three to four quantitative trait loci
(QTL) associated with resistance were found per isolate used. A major, putatively novel
QTL was identified on chromosome 5H, accounting for 23±48% of the genetic variation.
Additional QTL explaining between 12 and 16.5% were found on chromosomes 4H, 5H, 6H
and 7H, with the one on 6H being race-specific. The major QTL on 5H was also found in
adult plants under field conditions in three years (explaining up to 55%) and the 7H QTL was
found in field trials in one year. Additional adult plant resistance QTL on 3H, 6H and 7H were
significant in single years. The resistance on chromosomes 3H, 5H, 6H and 7H originates
from the more resistant parent Lavrans, while the resistance on 4H is conferred by Arve.
The genetic markers associated with the QTL found in this study will benefit marker-assisted
selection for resistance against net blotch.
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