Alvarez-Rivera Gerardo, Sanz Aurora, Cifuentes Alejandro, Ibánez Elena, Paape Timothy, Lucas M Mercedes, Pueyo José J
Laboratory of Foodomics, CIAL-CSIC, Institute of Food Science Research, Madrid, Spain.
Institute of Agricultural Sciences, ICA-CSIC, Madrid, Spain.
Front Plant Sci. 2022 Jul 7;13:933209. doi: 10.3389/fpls.2022.933209. eCollection 2022.
Mercury (Hg) contamination is increasing worldwide in both wild ecosystems and agricultural soils due to natural processes, but mostly to anthropic activities. The molecular mechanisms involved in Hg toxicity and tolerance in plants have been extensively studied; however, the role of flavonoids in response to Hg stress remains to be investigated. We conducted a metabolomic study to analyze the changes induced at the secondary metabolite level in three Hg-tolerant and one Hg-sensitive cultivars. A total of 46 flavonoid compounds, classified into five different flavonoid families: anthocyanidins, flavones, isoflavones, pterocarpan flavonoids, and flavanones, along with their respective glycoconjugate derivatives, were identified in leaf and root tissues. The synthesis of free isoflavones, followed by monoglycosylation and further malonylation was shown to be characteristic of root samples, whereas higher glycosylation, followed by further acylation with coumaric and ferulic acid was characteristic of leaf tissues. While minor changes were observed in leaves, significant quantitative changes could be observed in roots upon Hg treatment. Some flavonoids were strongly upregulated in roots, including malonylglucosides of biochanin A, formononetin and medicarpin, and aglycones biochanin, daidzein, and irisolidone. Hg tolerance appeared to be mainly associated to the accumulation of formononetin MalGlc, tricin GlcAGlcA, and afrormosin Glc II in leaves, whereas aglycone accumulation was associated with tolerance to Hg stress in roots. The results evidence the alteration of the flavonoid metabolic profile and their glycosylation processes in response to Hg stress. However, notable differences existed between varieties, both in the basal metabolic profile and in the response to treatment with Hg. Overall, we observed an increase in flavonoid production in response to Hg stress, and Hg tolerance appeared to be associated to a characteristic glycosylation pattern in roots, associated with the accumulation of aglycones and monoglycosylated flavonoids. The findings are discussed in the context of the flavonoid biosynthetic pathway to provide a better understanding of the role of these secondary metabolites in the response and tolerance to Hg stress in .
由于自然过程，尤其是人为活动，汞（Hg）污染在全球范围内的野生生态系统和农业土壤中都在增加。植物中汞毒性和耐受性的分子机制已得到广泛研究；然而，黄酮类化合物在应对汞胁迫中的作用仍有待研究。我们进行了一项代谢组学研究，以分析三种耐汞品种和一种汞敏感品种在次生代谢物水平上所诱导的变化。在叶片和根系组织中总共鉴定出46种黄酮类化合物，分为五个不同的黄酮类家族：花青素、黄酮、异黄酮、紫檀素黄酮类和黄烷酮，以及它们各自的糖缀合物衍生物。游离异黄酮的合成，随后是单糖基化和进一步的丙二酰化，被证明是根系样本的特征，而较高的糖基化，随后是香豆酸和阿魏酸的进一步酰化，是叶片组织的特征。虽然在叶片中观察到的变化较小，但在汞处理后，根系中可观察到显著的定量变化。一些黄酮类化合物在根系中强烈上调，包括鹰嘴豆芽素A、芒柄花素和苜蓿素的丙二酰葡萄糖苷，以及苷元鹰嘴豆芽素、大豆苷元和鸢尾酮。耐汞性似乎主要与叶片中芒柄花素丙二酰葡萄糖苷、小麦黄素葡萄糖醛酸苷和非洲防己碱葡萄糖苷II的积累有关，而苷元的积累与根系对汞胁迫的耐受性有关。结果证明了黄酮类代谢谱及其糖基化过程在应对汞胁迫时的改变。然而，无论是在基础代谢谱还是对汞处理的反应方面，不同品种之间都存在显著差异。总体而言，我们观察到黄酮类化合物的产生在应对汞胁迫时增加，并且耐汞性似乎与根系中一种特征性的糖基化模式有关，这种模式与苷元和单糖基化黄酮类化合物的积累有关。我们在黄酮类生物合成途径的背景下讨论了这些发现，以便更好地理解这些次生代谢物在植物对汞胁迫的反应和耐受性中的作用。
