Ma Bangya, Tredway Lane P
Department of Plant Pathology, North Carolina State University, Raleigh, NC, 27695, USA.
Pest Manag Sci. 2013 Dec;69(12):1369-78. doi: 10.1002/ps.3513. Epub 2013 Apr 15.
The fungus Sclerotinia homoeocarpa causes dollar spot, the most important turfgrass disease worldwide. Demethylation inhibitor (DMI) fungicides have been relied upon heavily to manage this disease. Presently, populations of S. homoeocarpa with reduced sensitivity or resistance to DMIs are widespread in the United States.
Cytochrome P450 sterol 14α-demethylase (ShCYP51) and its flanking regions were identified and sequenced in 29 isolates of S. homoeocarpa with a range of DMI sensitivities. No modifications were found in the gene coding and upstream regions that were consistently related to DMI sensitivity. In the absence of propiconazole, ShCYP51 was expressed at a similar low level among DMI baseline and resistant isolates. In the presence of propiconazole, DMI-resistant isolates were induced to express ShCYP51 at significantly higher levels than baseline isolates by propiconazole at 5 mg L(-1) for 5 h or at 0.5 mg L(-1) for 72 h. The ShCYP51 expression level after 72 h exposure to 0.5 mg L(-1) of propiconazole was linearly related to EC50 values and ΔRG (the change in relative growth rate over time), with R(2) values equal to 83.7 and 90.0% respectively.
Induced overexpression of ShCYP51 in resistant isolates following DMI exposure is an important factor determining DMI sensitivity in S. homoeocarpa.
真菌禾本科核盘菌引发币斑病，这是全球最重要的草坪草病害。脱甲基抑制剂（DMI）类杀菌剂一直被大量用于防治这种病害。目前，在美国，对DMI敏感性降低或具有抗性的禾本科核盘菌种群广泛存在。
在29株对DMI具有不同敏感性的禾本科核盘菌分离株中，鉴定并测序了细胞色素P450甾醇14α-脱甲基酶（ShCYP51）及其侧翼区域。在与DMI敏感性始终相关的基因编码区和上游区域未发现修饰。在没有丙环唑的情况下，ShCYP51在DMI敏感基线分离株和抗性分离株中的表达水平相似且较低。在有丙环唑存在的情况下，5 mg L⁻¹丙环唑处理5 h或0.5 mg L⁻¹丙环唑处理72 h后，DMI抗性分离株中ShCYP51的表达被诱导至显著高于敏感基线分离株的水平。暴露于0.5 mg L⁻¹丙环唑72 h后的ShCYP51表达水平与EC50值和ΔRG（相对生长速率随时间的变化）呈线性相关，R²值分别为83.7%和90.0%。
DMI暴露后抗性分离株中ShCYP51的诱导过表达是决定禾本科核盘菌对DMI敏感性的一个重要因素。
