Identification and mapping of net form of net blotch resistance in South African barley Anke Martin & Gregory J. Platz & Daniel de Klerk & Ryan A. Fowler & Francois Smit & Francois G. Potgieter & Renée Prins Received: 1 February 2018 /Accepted: 1 April 2018 # Springer Science+Business Media B.V., part of Springer Nature 2018 Abstract Net form of net blotch (NFNB) caused by the fungus Pyrenophora teres f. teres is an economically important foliar disease of barley (Hordeum vulgare) in southern and eastern Africa. Little attention has been given to disease resistance breeding, and knowledge about the presence of NFNB resistance in breeding lines is limited. Deploying resistance into varieties used in this region is important for future control of the disease. We have identified NFNB disease resistance in existing South African breeders’ lines and have mapped the resistance in line UVC8. Six different trials, three conducted in South Africa and another three in Austra- lia, were used to identify resistance QTL. A major QTL was identified on chromosome 6H having a LOD score of 40.5 and 55% of the phenotypic variance explained. Kompetitive Allele Specific PCR (KASP™) markers were designed for this QTL region. These and micro- satellite markers can now be used to routinely select for NFNB resistance. Keywords Hordeum vulgare . Net form of net blotch . Quantitative trait loci . KASP™ markers Introduction Net blotch caused by the ascomycete Pyrenophora teres (synonym Drechslera teres) is an important foliar dis- ease of barley (Hordeum vulgare). This fungus occurs as two forms, Pyrenophora teres f. teres and P. teres f. maculata, which can be distinguished on leaves of sus- ceptible barley lines. Net form of net blotch produces net-like necrotic lesions, whereas spot form of net blotch produces elliptical necrotic lesions surrounded by a chlorotic zone varying in width (Liu et al. 2011; Mathre 1997; McLean et al. 2009). A study investigat- ing the growth of P. teres in planta suggested that disease symptoms can be explained by differences in fungal growth of the two forms (Lightfoot and Able 2010). The spot blotch symptoms are due to the fungus initially growing as a biotroph and forming intracellular vesicles within epidermal cells before switching to the necrotrophic growth stage in the mesophyll, whereas the Mol Breeding (2018) 38:53 https://doi.org/10.1007/s11032-018-0814-1 Electronic supplementary material The online version of this article (https://doi.org/10.1007/s11032-018-0814-1) contains supplementary material, which is available to authorized users. A. Martin (*) Centre for Crop Health, University of Southern Queensland, Toowoomba, QLD 4350, Australia e-mail: anke.martin@usq.edu.au G. J. Platz : R. A. Fowler Queensland Department of Agriculture and Fisheries, Hermitage Research Facility, Warwick, QLD 4370, Australia D. de Klerk : F. Smit : F. G. Potgieter South African Barley Breeding Institute, PO Box 27, Caledon 7230, South Africa R. Prins CenGen (Pty) Ltd, 78 Fairbairn Street, Worcester 6850, South Africa R. Prins Department of Plant Sciences, University of the Free State, Bloemfontein 9300, South Africa