Phytophthora species can infect hundreds of different plants, including many important crops, causing a number of agriculturally relevant diseases. A key feature of attempted pathogen infection is the rapid production of the redox active molecule nitric oxide (NO). However, the potential role(s) of NO in plant resistance against Phytophthora is relatively unexplored. Here we show that the level of NO accumulation is crucial for basal resistance in Arabidopsis against Phytophthora parasitica. Counterintuitively, both relatively low or relatively high NO accumulation leads to reduced resistance against P. parasitica. S-nitrosylation, the addition of a NO group to a protein cysteine thiol to form an S-nitrosothiol, is an important route for NO bioactivity and this process is regulated predominantly by S-nitrosoglutathione reductase 1 (GSNOR1). Loss-of-function mutations in GSNOR1 disable both salicylic acid accumulation and associated signalling, and also the production of reactive oxygen species, leading to susceptibility towards P. parasitica. Significantly, we also demonstrate that secreted proteins from P. parasitica can inhibit Arabidopsis GSNOR1 activity.

中文翻译：

---

一氧化氮稳态的扰动促进拟南芥对寄生疫霉的易感性

疫霉属物种可以感染数百种不同的植物，包括许多重要的作物，导致许多农业相关疾病。试图感染病原体的一个关键特征是氧化还原活性分子一氧化氮 (NO) 的快速产生。然而，NO 在植物抗疫病中的潜在作用是相对未知的。在这里，我们表明 NO 积累水平对于拟南芥对寄生疫霉的基础抗性至关重要。与直觉相反，相对低或相对高的 NO 积累都会导致对P. parasitica的抵抗力降低。小号-亚硝基化，将 NO 基团添加到蛋白质半胱氨酸硫醇以形成S-亚硝基硫醇，是 NO 生物活性的重要途径，该过程主要受S-亚硝基谷胱甘肽还原酶 1 (GSNOR1) 调节。GSNOR1中的功能丧失突变使水杨酸积累和相关信号传导以及活性氧物质的产生都失效，导致对寄生假单胞菌的易感性。值得注意的是，我们还证明了来自P. parasitica的分泌蛋白可以抑制拟南芥GSNOR1 的活性。