Genetic analysis of virulence in the Pyrenophora teres f. teres population BB25×FGOH04Ptt-21.

Pyrenophora teres f. teres is the causal agent of net form net blotch (NFNB) of barley. In order to map the genetics of avirulence/virulence in P. teres f. teres, a fungal population was developed using P. teres f. teres isolates BB25 (Denmark) and FGOH04Ptt-21 (North Dakota, USA) due to these two isolates differing in virulence on several common barley lines. 109 progeny isolates were obtained from the BB25 by FGOH04Ptt-21 cross that were then used for NFNB disease evaluation across eight barley lines, four of which have been used commonly as NFNB differential lines as well as four cultivars commonly used in barley production in the Northern Great Plains. BB25 was virulent on one of the barley lines and avirulent on seven of the barley lines whereas, FGOH04Ptt-21 was virulent on all eight barley lines evaluated. Genetic maps were generated with single nucleotide polymorphism (SNP) markers obtained using a restriction associated DNA genotyping by sequencing (RAD-GBS) approach. Sixteen linkage groups were formed and were used to identify quantitative trait loci (QTL) associated with avirulence/virulence. Nine unique QTL were identified on eight linkage groups out of which three QTL had major effects (R2 ≥45%) while the remaining six QTL were relatively minor (R2 <20%). One or two major effect loci were identified for the lines commonly used as differentials. Conversely, variation in virulence on the local barley cultivars was mostly associated with small effect loci that contributed quantitatively to disease.