Identification and mapping of a gene conferring resistance to the spot form of net blotch (Pyrenophora teres f maculata) in barley

Spot form of net blotch (SFNB) (Pyrenophora teres f maculata) is an economi cally damaging foliar disease of barley in many of the world's cereal growi ng areas. The development of SFNB-resistant cultivars may be accelerated th rough the use of molecular markers. A screen for SFNB resistance in 96 line s identified four new sources of resistance, including a feed variety, 'Gal leon', for which a fully mapped doubled haploid population was available. S egregation data indicated SFNB resistance was conferred by a single gene in the 'Galleon' x 'Haruna Nijo' cross, positioned on the long arm of chromos ome 7H. This gene is designated Rpt4 and is flanked by the RFLP loci Xpsr-1 17 (D) and Xcdo673 at distances of 6.9 cM and 25.9 cM, respectively. The ma rker Xpsr117(D) was validated using another population segregating for Rpt4 , correctly predicting SFNB resistance with more than 90% accuracy.