BACKGROUND Food contamination with Salmonella enterica and enterohemorrhagic Escherichia coli is among the leading causes of foodborne illnesses worldwide and crop plants are associated with > 50% of the disease outbreaks. However, the mechanisms underlying the interaction of these human pathogens with plants remain elusive. In this study, we have explored plant resistance mechanisms against these enterobacteria and the plant pathogen Pseudomonas syringae pv. tomato (Pst) DC3118, as an opportunity to improve food safety. RESULTS We found that S. enterica serovar Typhimurium (STm) transcriptionally modulates stress responses in Arabidopsis leaves, including induction of two hallmark processes of plant defense: ROS burst and cell wall modifications. Analyses of plants with a mutation in the potentially STm-induced gene EXO70H4 revealed that its encoded protein is required for stomatal defense against STm and E. coli O157:H7, but not against Pst DC3118. In the apoplast however, EXO70H4 is required for defense against STm and Pst DC3118, but not against E. coli O157:H7. Moreover, EXO70H4 is required for callose deposition, but had no function in ROS burst, triggered by all three bacteria. The salicylic acid (SA) signaling and biosynthesis proteins NPR1 and ICS1, respectively, were involved in stomatal and apoplastic defense, as well as callose deposition, against human and plant pathogens. CONCLUSIONS The results show that EXO70H4 is involved in stomatal and apoplastic defenses in Arabidopsis and suggest that EXO70H4-mediated defense play a distinct role in guard cells and leaf mesophyll cells in a bacteria-dependent manner. Nonetheless, EXO70H4 contributes to callose deposition in response to both human and plant pathogens. NPR1 and ICS1, two proteins involved in the SA signaling pathway, are important to inhibit leaf internalization and apoplastic persistence of enterobacteria and proliferation of phytopathogens. These findings highlight the existence of unique and shared plant genetic components to fight off diverse bacterial pathogens providing specific targets for the prevention of foodborne diseases.

中文翻译：

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参与胼胝质介导的拟南芥防御沙门氏菌和大肠杆菌 O157:H7 的新分子成分。


背景技术肠道沙门氏菌和肠出血性大肠杆菌的食品污染是全世界食源性疾病的主要原因之一，并且农作物与> 50%的疾病爆发有关。然而，这些人类病原体与植物相互作用的机制仍然难以捉摸。在这项研究中，我们探索了植物对这些肠杆菌和植物病原体丁香假单胞菌的抗性机制。番茄（Pst）DC3118，作为改善食品安全的机会。结果我们发现鼠伤寒沙门氏菌 (STm) 可转录调节拟南芥叶片的应激反应，包括诱导植物防御的两个标志性过程：ROS 爆发和细胞壁修饰。对潜在 STm 诱导基因 EXO70H4 发生突变的植物进行的分析表明，其编码的蛋白质是针对 STm 和大肠杆菌 O157:H7 的气孔防御所必需的，但针对 Pst DC3118 则不需要。然而，在质外体中，需要 EXO70H4 来防御 STm 和 Pst DC3118，但不需要防御大肠杆菌 O157:H7。此外，EXO70H4 是胼胝质沉积所必需的，但在所有三种细菌触发的 ROS 爆发中没有功能。水杨酸 (SA) 信号和生物合成蛋白 NPR1 和 ICS1 分别参与针对人类和植物病原体的气孔和质外体防御以及胼胝质沉积。结论 结果表明，EXO70H4 参与拟南芥的气孔和质外体防御，表明 EXO70H4 介导的防御以细菌依赖性方式在保卫细胞和叶肉细胞中发挥独特的作用。尽管如此，EXO70H4 仍有助于胼胝质沉积，以响应人类和植物病原体。 NPR1 和 ICS1 是参与 SA 信号通路的两种蛋白质，对于抑制叶片内化和肠细菌质外体持久性以及植物病原体的增殖非常重要。这些发现强调了独特且共有的植物遗传成分的存在，可以抵抗多种细菌病原体，为预防食源性疾病提供了具体目标。