Department of Crop Science, Teagasc Crops Environment and Land Use Programme, Carlow, Ireland.
Centre for Agriculture, Food and Environmental Management Research, School of Life and Medical Sciences, University of Hertfordshire, Hertfordshire, UK.
Pest Manag Sci. 2024 May;80(5):2393-2404. doi: 10.1002/ps.7219. Epub 2022 Oct 26.
Light leaf spot, caused by Pyrenopeziza brassicae, is amongst the most damaging diseases of winter oilseed rape (Brassica napus), and currently the sterol 14α-demethylase (CYP51) inhibitors (azoles) represent the main class of fungicides used to control light leaf spot development. However, a shift in sensitivity to azole fungicides in P. brassicae populations has been observed in different European countries, including Ireland.
To assess the sensitivity status of Irish P. brassicae populations to azole fungicides, three collections of P. brassicae from 2018-2020 were tested in vitro against tebuconazole and prothioconazole-desthio, and the PbCYP51 gene targeted by this class of fungicides was genotyped in different isolates. A change in sensitivity to azole fungicides was observed and differences in sensitivity to tebuconazole between Irish populations were present. There were two substitutions within PbCYP51 (G460S and S508T) and inserts of different sizes in its promoter region. The presence of the G460S/S508T double mutant was reported for the first time, and the diversity in insert size was greater than previously known. Compared to wild type isolates, those carrying G460S or S508T were less sensitive to both fungicides and, where inserts were also identified, they further reduced sensitivity to azole fungicides.
The results of this study suggest that azole fungicides are still very effective in controlling light leaf spot in Ireland. However, using azole fungicides in mixtures of fungicides with different modes of action is recommended. © 2022 The Authors. Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.
由白锈菌（Pyrenopeziza brassicae）引起的光叶斑病是冬季油菜（Brassica napus）最具破坏性的病害之一，目前甾醇 14α-脱甲基酶（CYP51）抑制剂（唑类）是用于控制光叶斑病发展的主要杀菌剂类别。然而，在包括爱尔兰在内的不同欧洲国家，已经观察到白锈菌种群对唑类杀菌剂的敏感性发生了变化。
为了评估爱尔兰白锈菌种群对唑类杀菌剂的敏感性状况，对 2018-2020 年采集的三批白锈菌进行了体外测试，以测试其对戊唑醇和丙硫菌唑的敏感性，并对该类杀菌剂作用的靶标 PbCYP51 基因在不同分离物中的基因型进行了鉴定。观察到对白锈菌杀菌剂的敏感性发生了变化，并且爱尔兰种群对白锈菌杀菌剂的敏感性存在差异。在 PbCYP51 基因中存在两个替换（G460S 和 S508T）和启动子区域中不同大小的插入。首次报道了 G460S/S508T 双突变体的存在，并且插入大小的多样性大于以前已知的。与野生型分离物相比，携带 G460S 或 S508T 的分离物对两种杀菌剂的敏感性降低，而且在存在插入的情况下，它们进一步降低了对白锈菌杀菌剂的敏感性。
本研究结果表明，唑类杀菌剂在爱尔兰控制光叶斑病仍然非常有效。然而，建议在杀菌剂混合物中使用具有不同作用模式的杀菌剂。© 2022 作者。Pest Management Science 由 John Wiley & Sons Ltd 代表化学工业协会出版。
