Postulation of leaf (brown) rust resistance genes in 70 wheat cultivars grown in the United Kingdom

Multi-pathotype tests on 70 U.K. wheat cultivars permitted postulation of e ight known seedling genes for resistance to Puccinia recondita f. sp. triti ci either singly or in combinations. The most commonly detected gene was Lr 13 (present in approximately 57% of cultivars), followed by Lr26 (22%), Lr3 7 (20%), Lr10 (17%), Lr17b (LrH) (10%), Lr1 (7%), Lr3a (6%) and Lr20 (4%). This information permitted assessments of adult plant resistance (APR) in s ome cultivars, in field nurseries inoculated with pathotypes of P. recondit a f. sp. tritici of known pathogenicities for characterised seedling resist ance genes. APR was identified in eleven cultivars, including Avalon and Ma ris Ranger, which lacked detectable seedling resistance genes. The results provided a better understanding of specific resistances in the cultivars te sted than was available from previous reports.