Plants quickly accumulate reactive oxygen species (ROS) to resist against pathogen invasion, while pathogens strive to escape host immune surveillance by degrading ROS. However, the nature of the strategies that fungal pathogens adopt to counteract host‐derived oxidative stress is manifold and requires deep investigation. In this study, a superoxide dismutase (SOD) from Puccinia striiformis f. sp. tritici (Pst) PsSOD2 with a signal peptide (SP) and the glycophosphatidyl inositol (GPI) anchor, strongly induced during infection, was analysed for its biological characteristics and potential role in wheat–Pst interactions. The results showed that PsSOD2 encodes a Cu‐only SOD and responded to ROS treatment. Heterologous complementation assays in Saccharomyces cerevisiae suggest that the SP of PsSOD2 is functional for its secretion. Transient expression in Nicotiana benthamiana leaves revealed that PsSOD2 is localized to the plasma membrane. In addition, knockdown of PsSOD2 by host‐induced gene silencing reduced Pst virulence and resulted in restricted hyphal development and increased ROS accumulation. In contrast, heterologous transient assays of PsSOD2 suppressed flg22‐elicited ROS production. Taken together, our data indicate that PsSOD2, as a virulence factor, was induced and localized to the plasma membrane where it may function to scavenge host‐derived ROS for promoting fungal infection.

中文翻译：

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条锈菌中仅含铜的超氧化物歧化酶起着毒力因子的作用，可对抗宿主来源的氧化应激

植物会迅速积累活性氧（ROS）以抵抗病原体的入侵，而病原体则通过降解ROS来逃避宿主的免疫监视。但是，真菌病原体用来抵消宿主衍生的氧化应激的策略的性质是多种多样的，需要深入研究。在这项研究中，来自Puccinia striiformis f。的超氧化物歧化酶（SOD）。sp。分析了在感染过程中强烈诱导的带有信号肽（SP）和糖磷脂酰肌醇（GPI）锚的小麦（Pst）PsSOD2的生物学特性及其在小麦与Pst相互作用中的潜在作用。结果表明，PsSOD2编码仅含铜的SOD并响应ROS处理。酿酒酵母中的异源互补测定表明，PsSOD2的SP对其分泌起作用。在本氏烟草叶片中的瞬时表达表明，PsSOD2位于质膜上。此外，宿主诱导的基因沉默可降低PsSOD2的Pst毒力，并导致菌丝发育受限和ROS积累增加。相反，PsSOD2的异源瞬时测定抑制flg22引起的ROS产生。综上所述，我们的数据表明，作为致病因子的PsSOD2被诱导并定位于质膜，在该膜中它可能起到清除宿主来源的ROS促进真菌感染的作用。