Agricultural Research Council-Small Grain, Bethlehem 9700, South Africa.
Department of Plant Sciences, University of the Free State, Bloemfontein 9300, South Africa.
Plant Dis. 2024 Jan;108(1):20-29. doi: 10.1094/PDIS-06-23-1120-SR. Epub 2024 Jan 10.
Stem rust, caused by f. sp. (), is an important disease of wheat in South Africa (SA) and is primarily controlled using resistant cultivars. Understanding virulence diversity of is essential for successful breeding of resistant cultivars. Samples of infected wheat stems were collected across the major wheat-growing regions of SA from 2016 to 2020 to determine the pathogenic variability of isolates. Seven races were identified from 517 isolates pathotyped. The most frequently found races were 2SA104 (BPGSC + ,,) (35% frequency) and 2SA88 (TTKSF + ) (33%). Race 2SA42 (PTKSK + ), which was found in 2017, and 2SA5 (BFGSF + ), identified in 2017, are new races. The Ug99 variant race 2SA42 is similar in its virulence to 2SA107 (PTKST + ) except for avirulence to and virulence to . Race 2SA5 is closely related in its virulence to existing races that commonly infect triticale. Certain races showed limited geographical distribution. Races 2SA5, 2SA105, and 2SA108 were found only in the Western Cape, whereas 2SA107 and 2SA42 were detected only in the Free State province. The new and existing races were compared using microsatellite (SSR) marker analysis and their virulence on commercial cultivars was also determined. Seedling response of 113 wheat entries against the new races, using 2SA88, 2SA88+9h, 2SA106, and 2SA107 as controls, revealed 2SA107 as the most virulent (67 entries susceptible), followed by 2SA42 (64), 2SA106 (60), 2SA88+9h (59), 2SA88 (25), and 2SA5 (17). Thus, 2SA5 may not pose a significant threat to local wheat production. SSR genotyping revealed that 2SA5 is genetically distinct from all other SA races.
秆锈病由 f. sp. ()引起，是南非（SA）小麦的重要病害，主要通过抗性品种进行控制。了解的毒力多样性对于成功培育抗性品种至关重要。2016 年至 2020 年，在 SA 的主要小麦种植区采集了受感染的小麦茎样本，以确定分离物的致病性变异性。从 517 个被分型的分离物中鉴定出了 7 个小种。最常发现的小种是 2SA104（BPGSC +,,)（频率为 35%）和 2SA88（TTKSF + )（33%）。2017 年发现的 2SA42（PTKSK + )和 2017 年发现的 2SA5（BFGSF + )是新的小种。Ug99 变体 2SA42 与 2SA107（PTKST + )的毒力相似，除了对 和 的无毒力和对 的毒力。2SA5 在其毒力上与通常感染黑麦草的现有小种密切相关。某些小种的地理分布有限。2SA5、2SA105 和 2SA108 仅在西开普省发现，而 2SA107 和 2SA42 仅在自由州省发现。使用微卫星（SSR）标记分析比较了新的和现有的小种，并确定了它们对商业品种的毒力。使用 2SA88、2SA88+9h、2SA106 和 2SA107 作为对照，对 113 个小麦品种进行了针对新小种的幼苗反应，结果表明 2SA107 最为毒力（67 个品种易感），其次是 2SA42（64 个）、2SA106（60 个）、2SA88+9h（59 个）、2SA88（25 个）和 2SA5（17 个）。因此，2SA5 可能不会对当地小麦生产构成重大威胁。SSR 基因型分析表明，2SA5 在遗传上与南非所有其他小种不同。
