High frequency of fungicide resistance‐associated mutations in the wheat yellow rust pathogen Puccinia striiformis f. sp. tritici

Abstract

BACKGROUND: 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 offield failure of fungicides in a cereal rust diseasehas 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. RESULTS: 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. CONCLUSION: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.

Antifungal Activity of a Composition of Selenium and Iodine Nanoparticles

“…For instance, one of the problems with conventional fungicides today is fungal resistance to them. A vast number fungi, including plant pathogens, are reported to develop resistance to modern conventional fungicides (McDonald et al, 2019;Yang et al, 2019;Cook et al, 2021;Sevastos et al, 2018). Also conventional fungicides are shown to be toxic for humans (Lv et al, 2017;Knebel et al, 2019), animals (Gupta et al, 2018;Syromyatnikov et al, 2017;Wade et al, 2019;Kumar et al, 2020;Wu et al, 2018) and plants, including agricultural crops (Shahid et al, 2018;Fedotov et al, 2019).…”

The Evolving Battle Between Yellow Rust and Wheat: Implications for Global Food Security

“…However, of the three classes of fungicides active against Pst (demethylation inhibitors, DMIs; succinate dehydrogenase inhibitors, SDHIs; quinone outside inhibitors, QoIs), Pst resistance has evolved against two. Low levels of DHI resistance have been reported, and while high proportions of isolates carrying resistance associated mutations have been reported in some countries (Cook et al 2021), DHI resistance has so far had limited agronomic-scale signi cance (Oliver, 2014). SDHIs active against rusts have only been introduced relatively recently, giving less time for Pst resistance to evolve.…”

“…SDHIs active against rusts have only been introduced relatively recently, giving less time for Pst resistance to evolve. Nevertheless, sets of geographically diverse isolates have been identi ed that carry a mutation homologous to that linked to SDHI resistance in the related rust species P. pachyrhzi (Cook et al 2021). In the face of additional considerations such as changing regulation surrounding permissible chemistries, such evidence has led to the suggestion that the Pst risk classi cation should be upgraded (Oliver, 2014), fungicide resistance management practices be considered, and that systematic monitoring for Pst for fungicide resistance should be implemented (Cook et al 2021).…”

“…Nevertheless, sets of geographically diverse isolates have been identi ed that carry a mutation homologous to that linked to SDHI resistance in the related rust species P. pachyrhzi (Cook et al 2021). In the face of additional considerations such as changing regulation surrounding permissible chemistries, such evidence has led to the suggestion that the Pst risk classi cation should be upgraded (Oliver, 2014), fungicide resistance management practices be considered, and that systematic monitoring for Pst for fungicide resistance should be implemented (Cook et al 2021). Lastly, the optimisation of fungicide timing, as well as improved fungicide application technologies, represent areas where additional research and development is required (Carmona et al 2020).…”

Detection of Ramularia collo-cygni DMI- and SDHI-resistant field populations in Austria and the effect of fungicides on the population and genetic diversity

“…Resistance to SDH fungicides have been reported after a few years of usefirst in barley against P. teres or R. collo-cygni and later in several other pathogens e.g. Z. tritici and Puccinia striiformis in wheat (Cook et al, 2021;Piotrowska et al, 2017a). The SDH enzyme is composed of four nuclear-encoded subunits (sdh-A, sdh-B, sdh-C and sdh-D), whereby subunits sdh-B, sdh-C and sdh-D interact with SDHI fungicides, which can result in amino acid substitutions (Gutiérrez-Alonso et al, 2017;Sierotzki & Scalliet, 2013).…”