Abstract
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.
Highlights
The necrotrophic fungus Pyrenophora teres Drechsler (anamorph Drechslera teres (Sacc.) Shoemaker) is the causal agent of net blotch (NB), a foliar disease on barley, which occurs predominantly in cool and humid barley growing regions around the world [1]
The objectives of this study were (1) to identify and map quantitative trait loci (QTL) associated with resistance to NB in Norwegian barley cultivars, (2) to test whether these QTL are stable throughout different environments, years and developmental stages and (3) to assess whether resistance screenings at the seedling stage can be used to predict adult resistance under field conditions
Despite the genetic similarity of the parents Arve and Lavrans, the mapping population segregated for NB resistance in seedlings and adult plants, as well as for days to heading (DH) and plant height (PH) (Fig 1, S1 and S2 Figs)
Summary
The necrotrophic fungus Pyrenophora teres Drechsler (anamorph Drechslera teres (Sacc.) Shoemaker) is the causal agent of net blotch (NB), a foliar disease on barley, which occurs predominantly in cool and humid barley growing regions around the world [1]. In Norway, NB is an important barley disease with varying severity in different years and regions [4], but yield losses due to P. teres are not well-documented and reliable data is lacking. Both forms of the pathogen are found in Norway but it is not known which one is the dominant form
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