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. 2018 Mar;74(3):672-681.
doi: 10.1002/ps.4761. Epub 2017 Nov 23.

Non-target Site SDHI Resistance Is Present as Standing Genetic Variation in Field Populations of Zymoseptoria Tritici

Free PMC article

Non-target Site SDHI Resistance Is Present as Standing Genetic Variation in Field Populations of Zymoseptoria Tritici

Masao Yamashita et al. Pest Manag Sci. .
Free PMC article


Background: A new generation of more active succinate dehydrogenase (Sdh) inhibitors (SDHIs) is currently widely used to control Septoria leaf blotch in northwest Europe. Detailed studies were conducted on Zymoseptoria tritici field isolates with reduced sensitivity to fluopyram and isofetamid; SDHIs which have only just or not been introduced for cereal disease control, respectively.

Results: Strong cross-resistance between fluopyram and isofetamid, but not with other SDHIs, was confirmed through sensitivity tests using laboratory mutants and field isolates with and without Sdh mutations. The sensitivity profiles of most field isolates resistant to fluopyram and isofetamid were very similar to a lab mutant carrying SdhC-A84V, but no alterations were found in SdhB, C and D. Inhibition of mitochondrial Sdh enzyme activity and control efficacy in planta for those isolates was severely impaired by fluopyram and isofetamid, but not by bixafen. Isolates with similar phenotypes were not only detected in northwest Europe but also in New Zealand before the widely use of SDHIs.

Conclusion: This is the first report of SDHI-specific non-target site resistance in Z. tritici. Monitoring studies show that this resistance mechanism is present and can be selected from standing genetic variation in field populations. © 2017 The Authors. Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

Keywords: Septoria leaf blotch; fluopyram; fungicide resistance; isofetamid; succinate dehydrogenase inhibitor.


Figure 1
Figure 1
Chemical structures of six SDHIs tested in this study. Fluxapyroxad (1), bixafen (2), penthiopyrad (3), boscalid (4), fluopyram (5) and isofetamid (6).
Figure 2
Figure 2
Spearman's correlations between six SDHIs for Zymoseptoria tritici isolates with Sdh mutations shown in Table 2 (n = 22). Sensitivity data measured as EC50 (mg L−1) values were expressed with log10 scale. P < 0.05 means the correlation was statistically significant.
Figure 3
Figure 3
Sensitivity distribution of French and UK strains of Zymoseptoria tritici to bixafen, fluopyram and isofetamid. Isolates are ranked according increasing EC50 values (cumulative). French strains (n = 65) sampled from untreated plots near Lyon (n = 33) and Orleans (n = 32) in 2015. UK strains (n = 48) sampled from untreated plots at Rothamsted Research (Harpenden) in 2015.
Figure 4
Figure 4
PCR detection of the 519‐bp MgMFS1 promoter insert in Zymoseptoria tritici strains using primers MFF1 and MFR1. Samples of EasyLadder I (Bioline, London, UK) in lanes 1 and 16, products of strains Orleans 26 (lane 2), Lyon 35 (3), R15‐46 (4), Orleans 8 (5), Lyon 26 (6), Orleans 6 (7), Lyon 24 (8), Orleans 12 (9), Orleans 11 (10), Lyon 14 (11), Orleans 40 (12), Lyon 31 (13), Lyon 16 (14), NT321.17 (15), IPO323 (17) and Flu‐6 (18). No amplification for Lyon 24, Lyon 31 and water control (not shown). Largest product (1009 bp) in lane 14 and 15, Lyon 16 and NT321.17, respectively, indicates the presence of 519 bp promoter insert; no insert present in smaller 490 bp product.

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    1. Torriani SFF, Melichar JPE, Mills C, Pain N, Sierotzki H and Courbot M, Zymoseptoria tritici: a major threat to wheat production, integrated approaches to control. Fungal Genet Biol 79:8–12 (2015). - PubMed
    1. Griffin MJ and Fischer N, Laboratory studies on benzimidazole resistance in Septoria tritici . EPPO Bull 15:505–511 (1985).
    1. Cools HJ and Fraaije BA, Update on mechanisms of azole resistance in Mycosphaerella graminicola and implications for future control. Pest Manag Sci 69:150–155 (2013). - PubMed
    1. Fraaije BA, Cools HJ, Fountaine J, Lovell DJ, Motteram J, West JS et al, Role of ascospores in further spread of QoI‐resistant cytochrome b alleles (G143A) in field populations of Mycosphaerella graminicola . Phytopathology 95:933–941 (2005). - PubMed
    1. Schmeling BV and Kulka M, Systemic fungicidal activity of 1,4‐oxathiin derivatives. Science 152:659–660 (1966). - PubMed

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