Offor Benedict C, Mhlongo Msizi I, Steenkamp Paul A, Dubery Ian A, Piater Lizelle A
Department of Biochemistry, University of Johannesburg, Auckland Park, Johannesburg 2006, South Africa.
Metabolites. 2022 Apr 22;12(5):379. doi: 10.3390/metabo12050379.
Plants perceive pathogenic threats from the environment that have evaded preformed barriers through pattern recognition receptors (PRRs) that recognise microbe-associated molecular patterns (MAMPs). The perception of and triggered defence to lipopolysaccharides (LPSs) as a MAMP is well-studied in mammals, but little is known in plants, including the PRR(s). Understanding LPS-induced secondary metabolites and perturbed metabolic pathways in Arabidopsis will be key to generating disease-resistant plants and improving global plant crop yield. Recently, Arabidopsis LPS-binding protein (LBP) and bactericidal/permeability-increasing protein (BPI)-related proteins (LBP/BPI related-1) and (LBP/BPI related-2) were shown to perceive LPS from and trigger defence responses. In turn, brassinosteroid insensitive 1 (BRI1)-associated receptor kinase 1 (BAK1) is a well-established co-receptor for several defence-related PRRs in plants. Due to the lack of knowledge pertaining to LPS perception in plants and given the involvement of the afore-mentioned proteins in MAMPs recognition, in this study, Arabidopsis wild type (WT) and mutant ( and ) plants were pressure-infiltrated with LPSs purified from pv. DC3000 () and pv. 8004 (). Metabolites were extracted from the leaves at four time points over a 24 h period and analysed by UHPLC-MS, generating distinct metabolite profiles. Data analysed using unsupervised and supervised multivariate data analysis (MVDA) tools generated results that reflected time- and treatment-related variations after both LPS chemotypes treatments. Forty-five significant metabolites were putatively annotated and belong to the following groups: glucosinolates, hydroxycinnamic acid derivatives, flavonoids, lignans, lipids, oxylipins, arabidopsides and phytohormones, while metabolic pathway analysis (MetPA) showed enrichment of flavone and flavanol biosynthesis, phenylpropanoid biosynthesis, alpha-linolenic acid metabolism and glucosinolate biosynthesis. Distinct metabolite accumulations depended on the LPS chemotype and the genetic background of the and mutants. This study highlights the role of LPSs in the reprogramming Arabidopsis metabolism into a defensive state, and the possible role of LBR and BAK1 proteins in LPSs perception and thus plant defence against pathogenic bacteria.
植物通过模式识别受体（PRR）感知来自环境的致病威胁，这些受体能够识别微生物相关分子模式（MAMP），从而规避预先形成的屏障。在哺乳动物中，对作为MAMP的脂多糖（LPS）的感知和触发的防御反应已有深入研究，但在植物中，包括对相关PRR的了解却很少。了解拟南芥中LPS诱导的次生代谢产物和受干扰的代谢途径，将是培育抗病植物和提高全球农作物产量的关键。最近，拟南芥脂多糖结合蛋白（LBP）和杀菌/通透性增加蛋白（BPI）相关蛋白（LBP/BPI相关-1）以及（LBP/BPI相关-2）被证明能够感知来自[具体细菌名称]的LPS并触发防御反应。反过来，油菜素内酯不敏感1（BRI1）相关受体激酶1（BAK1）是植物中几种与防御相关的PRR的成熟共受体。由于缺乏关于植物中LPS感知的知识，且鉴于上述蛋白质参与MAMP识别，在本研究中，将拟南芥野生型（WT）和突变体（[具体突变体名称1]和[具体突变体名称2]）植株用从[细菌名称1]pv. [具体菌株名称1] DC3000（[具体菌株名称1]）和[细菌名称2]pv. [具体菌株名称2] 8004（[具体菌株名称2]）纯化的LPS进行压力浸润。在24小时内的四个时间点从叶片中提取代谢产物，并通过超高效液相色谱-质谱联用（UHPLC-MS）进行分析，生成不同的代谢产物谱。使用无监督和有监督的多变量数据分析（MVDA）工具分析数据，得到的结果反映了两种LPS化学类型处理后与时间和处理相关的变化。45种显著的代谢产物被初步注释，属于以下类别：芥子油苷、羟基肉桂酸衍生物、黄酮类、木脂素、脂质、氧脂素、拟南芥糖苷和植物激素，而代谢途径分析（MetPA）显示黄酮和黄烷醇生物合成、苯丙烷生物合成、α-亚麻酸代谢和芥子油苷生物合成富集。不同的代谢产物积累取决于LPS化学类型以及[具体突变体名称1]和[具体突变体名称2]突变体的遗传背景。本研究强调了LPS在将拟南芥代谢重编程为防御状态中的作用，以及LBR和BAK1蛋白在LPS感知从而植物对病原菌防御中的可能作用。
