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- Andersson, Björn, et al.
(författare)
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Spatio-temporal distribution of DMI and SDHI fungicide resistance of Zymoseptoria tritici throughout Europe based on frequencies of key target-site alterations
- 2021
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Ingår i: Pest Management Science. - : Wiley. - 1526-498X .- 1526-4998. ; 77, s. 5576-5588
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND Over the past decade, demethylation inhibitor (DMI) and succinate dehydrogenase inhibitor (SDHI) fungicides have been extensively used to control to septoria tritici blotch, caused by Zymoseptoria tritici on wheat. This has led to the development and selection of alterations in the target-site enzymes (CYP51 and SDH, respectively). RESULTS Taking advantage of newly and previously developed qPCR assays, the frequency of key alterations associated with DMI (CYP51-S524T) and SDHI (SDHC-T79N/I, C-N86S and C-H152R) resistance was assessed in Z. tritici-infected wheat leaf samples collected from commercial crops (n = 140) across 14 European countries prior to fungicide application in the spring of 2019. This revealed the presence of a West to East gradient in the frequencies of the most common key alterations conferring azole (S524T) and SDHI resistance (T79N and N86S), with the highest frequencies measured in Ireland and Great Britain. These observations were corroborated by sequencing (CYP51 and SDH subunits) and sensitivity phenotyping (prothioconazole-desthio and fluxapyroxad) of Z. tritici isolates collected from a selection of field samples. Additional sampling made at the end of the 2019 season confirmed the continued increase in frequency of the targeted alterations. Investigations on historical leaf DNA samples originating from different European countries revealed that the frequency of all key alterations (except C-T79I) has been gradually increasing over the past decade. CONCLUSION Whilst these alterations are quickly becoming dominant in Ireland and Great Britain, scope still exists to delay their selection throughout the wider European population, emphasizing the need for the implementation of fungicide antiresistance measures.
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| 2. |
- Berlin, Anna, et al.
(författare)
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Disease development and genotypic diversity of Puccinia graminis f. sp avenae in Swedish oat fields
- 2013
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Ingår i: Plant Pathology. - : Wiley. - 0032-0862 .- 1365-3059. ; 62, s. 32-40
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Tidskriftsartikel (refereegranskat)abstract
- The disease development and population structure of Puccinia graminis f. sp. avenae, which causes stem rust on oats, were studied to investigate if sexual reproduction plays an important role in the epidemiology of the disease. The genetic population structure of P. graminis f. sp. avenae in Sweden was investigated by sampling 10 oat fields in July and August 2008 and seven fields during the same period in 2009. Nine single-pustule isolates were first used to test simple sequence repeat (SSR) markers developed for P. graminis f. sp. tritici. Eleven of the 68 tested SSR markers were useful for genotyping P. graminis f. sp. avenae. For the main study, DNA from single uredinia was extracted and the SSR markers were used to genotype 472 samples. Both allelic and genotypic diversity were high in all fields, indicating that P. graminis f. sp. avenae undergoes regular sexual reproduction in Sweden. No significant relationship between genetic and geographic distances was found. Disease development was studied on two farms during 2008 and 2009. The apparent infection rates ranged between 0.17 and 0.55, indicating the potential for rapid disease development within fields. The incidence of oat stem rust has increased recently in Sweden. One possible explanation is a resurgence of its alternate host, barberry (Berberis spp.), after the repeal of the barberry eradication law in 1994. Barberry is present in several grain-producing areas in Sweden, which supports the conclusion that P. graminis f. sp. avenae undergoes regular sexual reproduction there.
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| 3. |
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| 4. |
- Berlin, Anna, et al.
(författare)
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Genetic variation in Puccinia graminis collected from oats, rye, and barberry
- 2012
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Ingår i: Phytopathology. - 0031-949X .- 1943-7684. ; 102, s. 1006-1012
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Tidskriftsartikel (refereegranskat)abstract
- Puccinia graminis, the causal agent of stem rust, was collected from its alternate host barberry (Berberis spp.) and two different uredinial hosts, oats (Avena sativa) and rye (Secale cereale). The samples were analyzed using 11 polymorphic simple sequence repeat (SSR) markers. There were large differences between fungal populations on oats (P. graminis f. sp. avenae) and rye (P. graminis f. sp. secalis), and the genetic variation within the different formae speciales was also high. It was possible to distinguish between the two formae speciales on barberry. Additional genotypic groups not present in the field samples from oats and rye were also identified on barberry. Our results confirm the importance of barberry in maintaining the populations of P. graminis in Sweden and the importance of the sexual stage for the survival of the pathogen.
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| 5. |
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| 6. |
- Berlin, Anna, et al.
(författare)
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Population structure of Puccinia graminis f.sp. avenae in Sweden
- 2009
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Konferensbidrag (refereegranskat)abstract
- Stem rust, caused by Puccinia graminis, is a serious disease of cereal crops and in the past this pathogen has caused severe epidemics worldwide. Incidence of oat stem rust in Sweden has increased recently. One possible explanation could be an increase in the occurrence of barberry (Berberis spp.), on which P. graminis sexual cycle can be completed, due to the repeal of the barberry eradication law in 1994. The epidemiology of P. graminis is not well known in Sweden. In this project, the population biology and epidemiology of P. graminis f. sp. avenae are investigated. Multiple samples of P. graminis f. sp. avenae were collected from 33 different oat fields during the summer of 2008. Single pustule isolates were obtained from the field collections and increased in a greenhouse. DNA from these isolates was extracted from urediniospores and infected leaf tissue and was used to screen Simple Sequence Repeat (SSR) markers developed for P. graminis f.sp. tritici. Some of the markers successfully produced amplicons indicating that they will be useful for genotyping isolates of P. graminis f. sp. avenae. Allele sizes for P. graminis f. sp. avenae were different than those from a U.S. reference isolate of P. graminis f.sp. tritici. A selected set of North American isolates of P. graminis f.sp. avenae are also included in the study. The results from this study will indicate if the oat stem rust pathogen in Sweden is a sexual population and the role of barberry in the epidemiology of P. graminis f. sp. avenae
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| 7. |
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| 8. |
- Berlin, Anna, et al.
(författare)
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Rusts on Berberis spp. in Sweden
- 2012
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- The barberry eradication law in Sweden was repealed in 1994, and incidence of barberry ( Berberis spp.) has increased as a consequence. To investigate the importance of barberry in survival and reproduction of cereal rust pathogens, aecia were collected during 2008-2010. Uredinia of P. graminis were collected from oats ( Avena sativa ) and rye ( Secale cereale ). The samples were analyzed using 11 polymorphic SSR markers. In addition, ITS (Internal transcript spacer region) and EF-1 α (Elongation factor-1 α ) were sequenced in samples collected from barberry, and the identit ies of the species were determined by comparing the sequences to BLAST databases. Cross-section al morpholog ies of a selection of samples of aecia and aeciospores were also examined. SSR marker results revealed large differences between the fungal populations on oats ( P. graminis f. sp. avenae ) and rye ( P. graminis f. sp. secalis ), and genetic variation within the different formae speciales was also high. It was possible to distinguish between the two formae speciales on barberry by SSR markers, ITS sequences and morphological characteristics. Additional genotypic groups of P. graminis not present in samples from either oats or rye were identified on barberry with the SSR markers. Our results confirm the importance of barberry for survival and maintenance of P. graminis populations in Sweden. A not yet identified species showing similar sequences to P. striiformis and P. poa-nemoralis was found on barberry.
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