Detection of virulence to septoria tritici blotch (STB) resistance conferred by the winter wheat cultivar Cougar in the Irish <i>Zymoseptoria tritici</i> population and potential implications for STB control

Kildea, Steven; Sheppard, Liam; Cucak, Mladen; Hutton, Fiona

doi:10.1111/ppa.13432

Cited by 9 publications

(5 citation statements)

References 20 publications

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“…An unmapped gene was introduced in Cougar, possibly from a line derived from T. dicoccoides, but virulent isolates were detected in the UK in 2015 (Caiazzo et al, 2019). Higher levels of Septoria than expected from RL ratings were detected on varieties bred from Cougar in Ireland in 2020 (Kildea et al, 2021) and there was a similar report from the UK in 2021 (AHDB, 2021). Cougar-virulent isolates were recovered from such varieties in Ireland (Kildea et al, 2021).…”

Section: Septoria Tritici Blotchsupporting

confidence: 53%

“…Higher levels of Septoria than expected from RL ratings were detected on varieties bred from Cougar in Ireland in 2020 (Kildea et al, 2021) and there was a similar report from the UK in 2021 (AHDB, 2021). Cougar-virulent isolates were recovered from such varieties in Ireland (Kildea et al, 2021). As ever with major genes, the Cougar resistance may have selected virulent genotypes of Z. tritici and is thus unlikely to be durable.…”

Section: Septoria Tritici Blotchsupporting

confidence: 53%

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Achievements in breeding cereals with durable disease resistance in Northwest Europe

Brown¹

2021

Burleigh Dodds Series in Agricultural Science

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Breeding cereals in Northwest Europe for durable resistance has made an important contribution to control of almost all economically significant diseases and pests of wheat, barley and oats. Durable resistance to fungal diseases is largely polygenic and quantitative, with the important exception of mlo resistance to powdery mildew of spring barley. Resistance to powdery mildew of winter wheat, spring barley and spring oats, brown rust of winter barley and Septoria nodorum blotch of wheat has been especially effective and durable. Resistance to Barley yellow mosaic virus and orange wheat blossom midge has used single genes which have so far been durable. Plant breeders are increasingly producing varieties with high or moderate resistance to all the most important diseases, and have successfully combined durable resistance with other traits which are important to farmers and end-users, including high yield, marketable grain quality and desirable agronomic properties.

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Section: Septoria Tritici Blotchsupporting

confidence: 53%

Section: Septoria Tritici Blotchsupporting

confidence: 53%

Achievements in breeding cereals with durable disease resistance in Northwest Europe

Brown¹

2021

Burleigh Dodds Series in Agricultural Science

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“…umbellulata that do not share common genomes with cultivated wheat (Table 4). Recently, the breakdown of resistance to Septoria tritici blotch (STB; a disease caused by the fungal pathogen Zymoseptoria tritici) in the winter wheat cultivar 'Cougar' and its derivatives has been reported in the UK and Ireland [224]. These findings show that diverse sources of resistance need to be deployed in disease resistance breeding programs.…”

Section: Diversification Of Resistance Genesmentioning

confidence: 99%

Introducing Beneficial Alleles from Plant Genetic Resources into the Wheat Germplasm

Sharma¹,

Schulthess

Bassi³

et al. 2021

Biology

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Wheat (Triticum sp.) is one of the world’s most important crops, and constantly increasing its productivity is crucial to the livelihoods of millions of people. However, more than a century of intensive breeding and selection processes have eroded genetic diversity in the elite genepool, making new genetic gains difficult. Therefore, the need to introduce novel genetic diversity into modern wheat has become increasingly important. This review provides an overview of the plant genetic resources (PGR) available for wheat. We describe the most important taxonomic and phylogenetic relationships of these PGR to guide their use in wheat breeding. In addition, we present the status of the use of some of these resources in wheat breeding programs. We propose several introgression schemes that allow the transfer of qualitative and quantitative alleles from PGR into elite germplasm. With this in mind, we propose the use of a stage-gate approach to align the pre-breeding with main breeding programs to meet the needs of breeders, farmers, and end-users. Overall, this review provides a clear starting point to guide the introgression of useful alleles over the next decade.

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“…The lack of broad spectrum STB resistance in wheat leaves agricultural systems vulnerable when major resistance genes are broken (e.g. the cultivar Gene in the USA, which was fully resistant in 1992 but become widely susceptible by 1995, causing substantial crop losses ( Cowger et al., 2000 ), or Cougar, which has become unpopular due to the development of Cougar-virulent strains of Z. tritici in the UK ( Kildea et al., 2021 ). Such problems will only become more frequent as effective fungicide protection options become more limited ( Birr et al., 2021 ).…”

Section: Introductionmentioning

confidence: 99%

A large bioassay identifies Stb resistance genes that provide broad resistance against Septoria tritici blotch disease in the UK

et al. 2023

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IntroductionSeptoria tritici blotch (STB) is one of the most damaging fungal diseases of wheat in Europe, largely due to the paucity of effective resistance genes against it in breeding materials. Currently dominant protection methods against this disease, e.g. fungicides and the disease resistance genes already deployed, are losing their effectiveness. Therefore, it is vital that other available disease resistance sources are identified, understood and deployed in a manner that maximises their effectiveness and durability.MethodsIn this study, we assessed wheat genotypes containing nineteen known major STB resistance genes (Stb1 through to Stb19) or combinations thereof against a broad panel of 93 UK Zymoseptoria tritici isolates. Seedlings were inoculated using a cotton swab and monitored for four weeks. Four infection-related phenotypic traits were visually assessed. These were the days post infection to the development of first symptoms and pycnidia, percentage coverage of the infected leaf area with chlorosis/necrosis and percentage coverage of the infected leaf area with pycnidia.ResultsThe different Stb genes were found to vary greatly in the levels of protection they provided, with pycnidia coverage at four weeks differing significantly from susceptible controls for every tested genotype. Stb10, Stb11, Stb12, Stb16q, Stb17, and Stb19 were identified as contributing broad spectrum disease resistance, and synthetic hexaploid wheat lines were identified as particularly promising sources of broadly effective STB resistances.DiscussionNo single Z. tritici isolate was found to be virulent against all tested resistance genes. Wheat genotypes carrying multiple Stb genes were found to provide higher levels of resistance than expected given their historical levels of use. Furthermore, it was noted that disease resistance controlled by different Stb genes was associated with different levels of chlorosis, with high levels of early chlorosis in some genotypes correlated with high resistance to fungal pycnidia development, potentially suggesting the presence of multiple resistance mechanisms.The knowledge obtained here will aid UK breeders in prioritising Stb genes for future breeding programmes, in which optimal combinations of resistance genes could be pyramided. In addition, this study identified the most interesting Stb genes for cloning and detailed functional analysis.

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Detection of virulence to septoria tritici blotch (STB) resistance conferred by the winter wheat cultivar Cougar in the Irish Zymoseptoria tritici population and potential implications for STB control

Cited by 9 publications

References 20 publications

Achievements in breeding cereals with durable disease resistance in Northwest Europe

Achievements in breeding cereals with durable disease resistance in Northwest Europe

Introducing Beneficial Alleles from Plant Genetic Resources into the Wheat Germplasm

A large bioassay identifies Stb resistance genes that provide broad resistance against Septoria tritici blotch disease in the UK

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