Zeiss Dylan R, Molinaro Antonio, Steenkamp Paul A, Silipo Alba, Piater Lizelle A, Di Lorenzo Flaviana, Dubery Ian A
Research Centre for Plant Metabolomics, Department of Biochemistry, University of Johannesburg, Auckland Park, South Africa.
Department of Chemical Sciences, University of Napoli Federico II, Complesso Universitario Monte Sant'Angelo, Naples, Italy.
Front Mol Biosci. 2023 Aug 10;10:1232233. doi: 10.3389/fmolb.2023.1232233. eCollection 2023.
one of the most destructive crop pathogens worldwide, causes bacterial wilt disease in a wide range of host plants. The major component of the outer membrane of Gram-negative bacteria, lipopolysaccharides (LPS), has been shown to function as elicitors of plant defense leading to the activation of signaling and defense pathways in several plant species. LPS from a strain virulent on tomato (LPS), were purified, chemically characterized, and structurally elucidated. The lipid A moiety consisted of tetra- to hexa-acylated -phosphorylated disaccharide backbone, also decorated by aminoarabinose residues in minor species, while the O-polysaccharide chain consisted of either linear tetrasaccharide or branched pentasaccharide repeating units containing α-L-rhamnose, -acetyl-β-D-glucosamine, and β-L-xylose. These properties might be associated with the evasion of host surveillance, aiding the establishment of the infection. Using untargeted metabolomics, the effect of LPS elicitation on the metabolome of leaves was investigated across three incubation time intervals with the application of UHPLC-MS for metabolic profiling. The results revealed the production of oxylipins, e.g., trihydroxy octadecenoic acid and trihydroxy octadecadienoic acid, as well as several hydroxycinnamic acid amide derivatives, e.g., coumaroyl tyramine and feruloyl tyramine, as phytochemicals that exhibit a positive correlation to LPS treatment. Although the chemical properties of these metabolite classes have been studied, the functional roles of these compounds have not been fully elucidated. Overall, the results suggest that the features of the LPS chemotype aid in limiting or attenuating the full deployment of small molecular host defenses and contribute to the understanding of the perturbation and reprogramming of host metabolism during biotic immune responses.
作为全球最具破坏性的作物病原体之一，可在多种寄主植物中引发青枯病。革兰氏阴性菌外膜的主要成分脂多糖（LPS）已被证明可作为植物防御的激发子，导致多种植物物种中的信号传导和防御途径被激活。从一株对番茄具有毒性的菌株中纯化出LPS，对其进行了化学表征和结构解析。脂多糖A部分由四至六酰化的磷酸化二糖主链组成，在少数物种中还带有氨基阿拉伯糖残基修饰，而O-多糖链由线性四糖或支链五糖重复单元组成，包含α-L-鼠李糖、N-乙酰-β-D-葡萄糖胺和β-L-木糖。这些特性可能与逃避宿主监测有关，有助于感染的建立。利用非靶向代谢组学，通过超高效液相色谱-质谱联用技术进行代谢谱分析，研究了LPS激发在三个孵育时间间隔内对番茄叶片代谢组的影响。结果显示，氧脂类物质如三羟基十八碳烯酸和三羟基十八碳二烯酸以及几种羟基肉桂酸酰胺衍生物如香豆酰酪胺和阿魏酰酪胺作为与LPS处理呈正相关的植物化学物质被产生。尽管已经对这些代谢物类别的化学性质进行了研究，但这些化合物的功能作用尚未完全阐明。总体而言，结果表明LPS化学型的特征有助于限制或减弱小分子宿主防御的全面展开，并有助于理解生物免疫反应期间宿主代谢的扰动和重编程。
