First and eighth authors: Department of Plant Sciences, University of the Free State, P.O. Box 339, Bloemfontein, 9300, South Africa; second and fourth authors: Epidemiology and Modelling Group, Department of Plant Sciences, University of Cambridge, Cambridge, CB2 3EA, UK; third author: Plant Breeding Institute Cobbitty, The University of Sydney, Private Mail Bag 11, Camden, NSW 2570, Australia; fifth and sixth authors: Atmospheric Dispersion and Air Quality (ADAQ), Met Office, Exeter, EX1 3PB, UK; and seventh author: International Maize and Wheat Improvement Center (CIMMYT), P.O. Box 5689, Addis Ababa, Ethiopia.
Phytopathology. 2019 Jan;109(1):133-144. doi: 10.1094/PHYTO-04-18-0110-R. Epub 2018 Dec 3.
The Australian wheat stem rust (Puccinia graminis f. sp. tritici) population was shaped by the introduction of four exotic incursions into the country. It was previously hypothesized that at least two of these (races 326-1,2,3,5,6 and 194-1,2,3,5,6 first detected in 1969) had an African origin and moved across the Indian Ocean to Australia on high-altitude winds. We provide strong supportive evidence for this hypothesis by combining genetic analyses and complex atmospheric dispersion modeling. Genetic analysis of 29 Australian and South African P. graminis f. sp. tritici races using microsatellite markers confirmed the close genetic relationship between the South African and Australian populations, thereby confirming previously described phenotypic similarities. Lagrangian particle dispersion model simulations using finely resolved meteorological data showed that long distance dispersal events between southern Africa and Australia are indeed possible, albeit rare. Simulated urediniospore transmission events were most frequent from central South Africa (viable spore transmission on approximately 7% of all simulated release days) compared with other potential source regions in southern Africa. The study acts as a warning of possible future P. graminis f. sp. tritici dispersal events from southern Africa to Australia, which could include members of the Ug99 race group, emphasizing the need for continued surveillance on both continents.
澳大利亚小麦秆锈病（Puccinia graminis f. sp. tritici）种群是由四次外来入侵形成的。此前有假设认为，其中至少有两次（于 1969 年首次发现的 326-1、2、3、5、6 号和 194-1、2、3、5、6 号）起源于非洲，并通过高空风跨越印度洋到达澳大利亚。我们通过结合遗传分析和复杂的大气扩散模型，为这一假说提供了强有力的支持证据。使用微卫星标记对 29 种澳大利亚和南非小麦秆锈病菌（P. graminis f. sp. tritici）进行遗传分析，证实了南非和澳大利亚种群之间的密切遗传关系，从而证实了先前描述的表型相似性。使用精细分辨率气象数据的拉格朗日粒子扩散模型模拟表明，南非和澳大利亚之间的远距离扩散事件确实是可能的，尽管很少见。与南部非洲其他潜在的源区相比，从中部南非（大约 7%的所有模拟释放日都可进行有活力孢子传播）模拟的冬孢子传播事件最为频繁。该研究提醒人们注意南非小麦秆锈病菌（P. graminis f. sp. tritici）可能向澳大利亚的未来扩散事件，其中可能包括 Ug99 菌系群的成员，这强调了在两个大陆继续进行监测的必要性。
