Background and Aims Plant diseases caused by Pectobacterium atrosepticum are often accompanied by extensive rot symptoms. In addition, these bacteria are able to interact with host plants without causing disease for long periods, even throughout several host plant generations. There is, to date, no information on the comparative physiology/biochemistry of symptomatic and asymptomatic plant–P. atrosepticum interactions. Typical (symptomatic) P. atrosepticum infections are associated with the induction of plant responses mediated by jasmonates, which are one of the products of the lipoxygenase cascade that gives origin to many other oxylipins with physiological activities. In this study, we compared the functioning of the lipoxygenase cascade following typical and latent (asymptomatic) infections to gain better insight into the physiological basis of the asymptomatic and antagonistic coexistence of plants and pectobacteria. Methods Tobacco plants were mock-inoculated (control) or infected with the wild type P. atrosepticum (typical infection) or its coronafacic acid-deficient mutant (latent infection). The expression levels of the target lipoxygenase cascade-related genes were assessed by Illumina RNA sequencing. Oxylipin profiles were analysed by GC-MS. With the aim of revising the incorrect annotation of one of the target genes, its open reading frame was cloned to obtain the recombinant protein, which was further purified and characterized using biochemical approaches. Key Results The obtained data demonstrate that when compared to the typical infection, latent asymptomatic P. atrosepticum infection is associated with (and possibly maintained due to) decreased levels of 9-lipoxygenase branch products and jasmonic acid and increased level of cis-12-oxo-10,15-phytodienoic acid. The formation of 9-oxononanoic acid and epoxyalcohols in tobacco plants was based on the identification of the first tobacco hydroperoxide lyase (HPL) with additional epoxyalcohol synthase (EAS) activity. Conclusions Our results contribute to the hypothesis of the oxylipin signature, indicating that different types of plant interactions with a particular pathogen are characterized by the different oxylipin profiles of the host plant. In addition, the tobacco LOC107825278 gene was demonstrated to encode an NtHPL (CYP74C43) enzyme yielding volatile aldehydes and aldoacids (HPL products) as well as oxiranyl carbinols (EAS products).

中文翻译：

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典型和潜伏的黑腐果杆菌感染过程中脂氧合酶级联的差异调节


背景和目的 由黑腐果杆菌引起的植物病害通常伴有广泛的腐烂症状。此外，这些细菌能够与宿主植物相互作用，即使在宿主植物的几代中，也不会长时间引起疾病。迄今为止，还没有关于有症状和无症状植物-P的比较生理学/生物化学的信息。间质相互作用。典型的（有症状的）黑脓杆菌感染与茉莉酸介导的植物反应的诱导有关，茉莉酸是脂氧合酶级联的产物之一，它是许多其他具有生理活性的氧脂素的起源。在这项研究中，我们比较了典型和潜伏（无症状）感染后脂氧合酶级联的功能，以更好地了解植物和果胶细菌无症状和拮抗共存的生理基础。方法用野生型黑腐病菌（典型感染）或其冠状酸缺陷突变体（潜伏感染）模拟接种（对照）或感染烟草植物。通过 Illumina RNA 测序评估目标脂氧合酶级联相关基因的表达水平。通过 GC-MS 分析 Oxylipin 谱。为了修正其中一个靶基因的错误注释，克隆了其开放阅读框以获得重组蛋白，并利用生化方法对其进行进一步纯化和表征。主要结果 获得的数据表明，与典型感染相比，潜伏无症状疟原虫。 atrosepticum 感染与 9-脂氧合酶分支产物和茉莉酸水平降低以及 cis-12-oxo-10,15-phytodienoic 酸水平升高有关（并且可能由于）而维持。烟草植物中 9-氧壬酸和环氧醇的形成基于第一个具有额外环氧醇合酶 (EAS) 活性的烟草氢过氧化物裂合酶 (HPL) 的鉴定。结论我们的结果有助于氧脂素特征的假设，表明植物与特定病原体的不同类型的相互作用以宿主植物的不同氧脂素谱为特征。此外，烟草LOC107825278基因被证明编码NtHPL（CYP74C43）酶，产生挥发性醛和醛酸（HPL产品）以及环氧乙烷甲醇（EAS产品）。