Characterization and mapping of gene Rph19 conferring resistance to Puccinia hordei in the cultivar ‘Reka 1’ and several Australian barleys

Previous studies established that the Australian barley cultivar ‘Prior’ possessed resistance to Puccinia hordei (RphP), displaying the same specificity as an uncharacterized resistance in the differential cultivar ‘Reka 1’ (also possessing Rph2). Multipathotype tests confirmed the presence RphP in nine additional barley cultivars and indicated that RphP differed in specificity to the genes Rph1 to Rph15 and Rph18, plus the gene RphX present in the barley cultivar ‘Shyri’. RphP was inherited as a single dominant gene. Mapping studies using a doubled haploid population derived from ‘Chebec’/‘Harrington’ located RphP to the long arm of chromosome 7H, and demonstrated linkage with an restriction fragment length polymorphism marker (pTAG732), a resistance gene analogue marker (RLch4(Nc)), and two microsatellite markers (HVM11 and HVM49) at genetic distances of about 4-10 cM. RphP showed linkage of 28 ± 4.3 cM with Rph3. RphP was designated Rph19, with the allele designation Rph19.ah. Previous studies have established that virulence for Rph19 occurs in many barley growing regions of the world.