Exserohilum turcicum is the causal agent of northern leaf blight (NLB) disease in sorghum and maize. Early detection of this economically important pathogen is essential for effective disease management to limit yield losses. Here we present a real-time quantitative PCR (qPCR) assay specific for E. turcicum detection and biomass quantification in sorghum and maize. In planta fungal quantification was achieved through amplification of a cytochrome P450 oxidoreductase (cpr1) gene fragment and subsequent normalisation to the host glutathione S-transferase III gene (gst3). The assay could specifically detect E. turcicum in sorghum and maize, but the cpr1 gene fragment was not amplified in non-target fungal pathogens. Application of the assay with NLB diseased sorghum and maize leaf material revealed a significant increase in E. turcicum DNA in leaves with lesion symptoms when compared to leaves with early stage chlorotic fleck symptoms in both hosts. Furthermore, E. turcicum was detected at levels as low as 1 pg in infected sorghum and maize leaves. The assay enables rapid detection and quantification of E. turcicum in sorghum and maize and has useful applications in crop breeding programmes and disease management where cultivar selection and early detection of the pathogen are essential to limit disease spread.

中文翻译：

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北方叶疫病高粱和玉米叶片中Exserohilum turcicum的定量检测

Exserohilum turcicum 是高粱和玉米中北方叶枯病 (NLB) 病害的病原体。早期检测这种具有重要经济意义的病原体对于有效管理疾病以限制产量损失至关重要。在这里，我们提出了一种实时定量 PCR (qPCR) 检测，专门用于高粱和玉米中的 E. turcicum 检测和生物量定量。在植物中，真菌定量是通过细胞色素 P450 氧化还原酶 (cpr1) 基因片段的扩增和随后对宿主谷胱甘肽 S-转移酶 III 基因 (gst3) 的标准化来实现的。该测定法可以特异性检测高粱和玉米中的 E. turcicum，但 cpr1 基因片段在非目标真菌病原体中未扩增。对 NLB 患病高粱和玉米叶材料应用该测定显示大肠杆菌显着增加。与两个宿主中具有早期褪绿斑点症状的叶子相比，具有病变症状的叶子中的 turcicum DNA 的差异。此外，在受感染的高粱和玉米叶子中检测到的 E. turcicum 含量低至 1 pg。该测定能够快速检测和量化高粱和玉米中的 E. turcicum，并在作物育种计划和疾病管理中具有有用的应用，其中品种选择和病原体的早期检测对于限制疾病传播至关重要。