ABSTRACT Arabidopsis thaliana exhibits durable ‘non-host’ resistance against the hemibiotrophic fungal pathogen Colletotrichum tropicale that infects mulberry plants. Arabidopsis non-host resistance comprises two layers of defense: preinvasive and postinvasive resistance. The EDR1 protein kinase contributes to Arabidopsis preinvasive resistance against C. tropicale by inducing the expression of plant defensin (PDF) genes. Here we report that the expressions of multiple PDF genes were strongly induced in Arabidopsis upon invasion by C. tropicale. Invasion by a necrotrophic pathogen, Alternaria brassicicola, also induced PDF expression. Importantly, PDF expression triggered upon invasion by both pathogens was inhibited in edr1 mutants, indicating the requirement of EDR1 for PDF expression in postinvasive resistance by Arabidopsis. Analysis of ora59 mutants also revealed that this gene is critical for induced PDF expression following pathogen invasion. Furthermore, inoculation assays of A. brassicicola indicated that ORA59 is involved in postinvasive resistance against the pathogen, suggesting invasion-triggered PDF expression contributes to postinvasive resistance in Arabidopsis.

中文翻译：

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真菌病原体入侵引发的植物防御素表达取决于拟南芥中的 EDR1 蛋白激酶和 ORA59 转录因子

摘要 拟南芥对感染桑树的半生物营养型真菌热带炭疽病菌表现出持久的“非宿主”抗性。拟南芥非宿主抗性包括两层防御：侵入前和侵入后抵抗。EDR1 蛋白激酶通过诱导植物防御素 (PDF) 基因的表达促进拟南芥对热带假丝酵母的侵袭前抗性。在这里我们报告了在拟南芥中被热带念珠菌入侵后，多个 PDF 基因的表达被强烈诱导。坏死性病原体 Alternaria brasicicola 的入侵也诱导了 PDF 表达。重要的是，在两种病原体入侵时触发的 PDF 表达在 edr1 突变体中被抑制，表明 EDR1 在拟南芥侵袭后抗性中需要 PDF 表达。ora59 突变体的分析还表明，该基因对于病原体入侵后诱导的 PDF 表达至关重要。此外，A. brasicicola 的接种试验表明 ORA59 参与针对病原体的侵袭后抗性，表明侵袭触发的 PDF 表达有助于拟南芥的侵袭后抗性。