John Innes Centre, Norwich Research Park, Norwich, UK.
The New Zealand Institute for Plant & Food Research Limited, Lincoln, New Zealand.
Pest Manag Sci. 2021 Jul;77(7):3358-3371. doi: 10.1002/ps.6380. Epub 2021 May 3.
Reliance on fungicides to manage disease creates selection pressure for the evolution of resistance in fungal and oomycete pathogens. Rust fungi (Pucciniales) are major pathogens of cereals and other crops and have been classified as low-risk for developing resistance to fungicides; no case of field failure of fungicides in a cereal rust disease has yet been recorded. Recently, the Asian soybean rust pathogen, Phakopsora pachyrhizi evolved resistance to several fungicide classes, prompting us to screen a large sample of the globally widespread wheat yellow rust pathogen, Puccinia striiformis f. sp. tritici (Pst), for mutations associated with fungicide resistance.
We evaluated 363 Pst isolates from Europe, the USA, Ethiopia, Chile, China and New Zealand for mutations in the target genes of demethylase inhibitor (DMI; Cyp51) and succinate dehydrogenase inhibitor (SDHI; SdhB, SdhC and SdhD) fungicides. A high proportion of Pst isolates carrying a Y134F DMI resistance-associated substitution in the Cyp51 gene was found among those from China and New Zealand. A set of geographically diverse Pst isolates was also found to display a substitution in SdhC (I85V) that is homologous to that reported recently in P. pachyrhizi and linked to SDHI resistance.
The identification of resistance-associated alleles confirms that cereal rusts are not immune to fungicide resistance and that selection for resistance evolution is operating at high levels in certain locations. It highlights the need to adopt fungicide resistance management practices and to monitor cereal rust species for development of resistance. © 2021 The Authors. Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.
依赖杀菌剂来防治病害会对真菌和卵菌病原体产生抗药性进化造成选择压力。锈菌（锈菌目）是谷类作物和其他作物的主要病原体，被归类为对杀菌剂产生抗药性的风险较低；尚未记录到谷物锈病中杀菌剂田间失效的情况。最近，亚洲大豆锈病病原菌 Phakopsora pachyrhizi 对几类杀菌剂产生了抗药性，这促使我们对全球广泛分布的小麦条锈病病原菌 Puccinia striiformis f. sp. tritici（Pst）进行大规模筛选，以寻找与抗药性相关的突变。
我们评估了来自欧洲、美国、埃塞俄比亚、智利、中国和新西兰的 363 个 Pst 分离株，以确定其目标基因（脱甲基酶抑制剂（DMI； Cyp51）和琥珀酸脱氢酶抑制剂（SDHI；SdhB、SdhC 和 SdhD）杀菌剂的突变情况。在中国和新西兰的 Pst 分离株中，发现了携带 Cyp51 基因中 Y134F DMI 抗性相关取代的 Pst 分离株比例较高。一组具有地理多样性的 Pst 分离株也被发现具有 SdhC（I85V）的取代，该取代与最近在 P. pachyrhizi 中报道的取代同源，并与 SDHI 抗性相关。
抗性相关等位基因的鉴定证实，谷物锈病并非对杀菌剂具有免疫力，而且在某些地区，抗药性进化的选择压力很高。这突出表明需要采取杀菌剂抗药性管理措施，并对谷物锈病物种进行监测，以防止抗药性的发展。
