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Pathogenicity Spectra and Screening for Resistance in Barley Against Tunisian Pyrenophora teres f. teres

October 2012 , Volume 96 , Number  10
Pages  1,569 - 1,575

Aida Bouajila and Néjia Zoghlami, Centre de Biotechnologie de Borj-Cédria, BP 901, Hammam-Lif 2050, Tunisia; Maha Al Ahmed and Michael Baum, International Center for Agricultural Research in the Dry Areas (ICARDA), Aleppo, Syria; Abdelwahed Ghorbel, Centre de Biotechnologie de Borj-Cédria; and Kumarse Nazari, ICARDA

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Accepted for publication 6 May 2012.

This work aimed to determine patterns of pathogenicity in Pyrenophora teres f. teres and to identify potentially effective resistance sources that could be used as breeding material to control net blotch in Tunisia. Extensive pathogenic variability was detected in 85 isolates of P. teres causing net blotch of barley in Tunisia. Based on unweighted pair-group method with arithmetic averaging clustering and mean disease rating scores, three distinct virulence groups were identified. The isolates were classified into 23 pathotypes. Pathogenic variability within the groups was higher than that between the groups, a finding that can guide a rational choice of isolates for screening lines as part of a breeding program. Conversely, studying the relationship between geographic and pathotypic structure allowed us to detect a significant isolation by distance pattern, suggesting a regular and gradual dispersal of the pathogen over this spatial scale. Using specific resistance properties of individual barley genotypes as virulence markers, all the differential barley genotypes were shown to be distinct, and no single source of resistance was totally effective against all isolates.

This article is in the public domain and not copyrightable. It may be freely reprinted with customary crediting of the source. The American Phytopathological Society, 2012.