Cultivated barley (Hordeum vulgare) is an important winter cereal in South Africa (SA), ranked second after wheat. Leaf rust, caused by Puccinia hordei Otth. (Ph), is one of the most common diseases affecting grain yield and quality of barley. In this study, isolates of Ph were pathotyped using differential cultivars and lines with designated Rph-resistance genes, as well as a set of Bowman introgression lines (BW) containing resistance genes Rph1 to Rph15. Single pustule isolates derived from recently collected field isolates, typed as Ph race UVPh7235, showed increased virulence to Rph3 when compared with previously described races from SA. Discrepancies in phenotypic responses were recorded between standard differential lines carrying Rph2, Rph6 and Rph9 and the corresponding BW lines. Results for barley cultivars with designated sources of adult plant resistance revealed low seedling infection types (ITs) for Baronesse (Rph20 + Rph24) to all Ph isolates and for Lenka (Rph20 + Rph23 + Rph24) to isolates of Ph races UVPh3231 and UVPh7231. The barley cultivars Agulhas and Cristalia showed low seedling ITs and moderate to high levels of adult plant resistance under field and greenhouse conditions, respectively. Genotyping of 48 Ph isolates with 20 microsatellite markers revealed five closely related genetic lineages with low gene diversity and allelic richness levels. While STRUCTURE analysis revealed three clusters, no clear division of the isolates into the clusters was evident, as the isolates were admixed for all three. Linkage disequilibrium analysis, as well as higher H_O versus H_E values, supported the hypothesis that the South African Ph population is clonal, consisting of a single genetic lineage.

栽培大麦（Hordeum vulgare）是南非（SA）重要的冬季谷物，仅次于小麦。叶锈病，由Puccinia hordei Otth 引起。( Ph )，是影响大麦产量和品质的最常见病害之一。在这项研究中，使用具有指定Rph抗性基因的差异栽培品种和品系以及一组含有抗性基因Rph1至Rph15的鲍曼基因渗入系 (BW) 对Ph分离株进行病理分型。来自最近收集的田间分离株的单个脓疱分离株，类型为Ph种族 UVPh7235，显示对Rph3的毒力增加与之前描述的 SA 比赛相比。在携带Rph2、Rph6和Rph9的标准差异系与相应的 BW 系之间记录了表型反应的差异。具有指定成株抗性来源的大麦品种的结果显示，Baronesse ( Rph20  +  Rph24 ) 对所有Ph分离株和 Lenka ( Rph20  +  Rph23  +  Rph24 ) 对Ph分离株的幼苗感染类型 (ITs) 较低种族 UVPh3231 和 UVPh7231。大麦品种 Agulhas 和 Cristalia 在田间和温室条件下分别表现出低的幼苗 IT 和中到高水平的成株抗性。用 20 个微卫星标记对 48 个Ph分离株进行基因分型揭示了 5 个密切相关的遗传谱系，它们的基因多样性和等位基因丰富度水平较低。虽然 STRUCTURE 分析揭示了三个簇，但没有明显将分离物明确划分为簇，因为分离物混合了所有三个簇。连锁不平衡分析，以及较高的 H _O与 H _E值，支持南非Ph种群是克隆的假设，由单一遗传谱系组成。