Uncovering the crucial metabolic pathways in the invasive plant Hydrocotyle verticillata for defence against copper exposure by integrative transcriptome and metabolome analysis

Abstract

To throw light on the underlying strategies of Hydrocotyle verticillata coping with potentially toxic elements (PTEs) exposure. In this study, variations in the transcriptome and metabolomics of the leaves of plants exposed to various concentrations of copper ions (Cu²⁺) for 7 d were analyzed. Several crucial metabolic pathways involved in leaf defense against Cu²⁺ exposure were identified using integrative transcriptome and metabolome analysis. The pathways for plants coping with Cu²⁺ exposure were associated with carotenoid metabolism, amino acid metabolism, cutin, suberin, and wax biosynthesis, plant hormonal signal transduction, phenylpropanoid and terpenoid metabolisms. In the 90.0 μM Cu²⁺ treatment, abscisic acid 8′-hydroxylase was upregulated, reducing abscisic acid content, while downregulation of the BAK1 gene and pathogen-related protein genes triggered programmed cell death The positive role of antheraxanthin, γ-L-glutamylcysteine, γ-aminobutyric acid, and carnosine in the plant defense against 45.0 μM Cu²⁺ was observed. Lutein, 3,4-dihydrospheroidene, linoleic acid, glutamine, pyroglutamic acid, the gene encoding brassinosteroid resistant 1/2, and xyloglucan:xyloglucosyl transferase are involved in plant defense against 90.0 μM Cu²⁺. Compared to 0 mM, both Cu²⁺ treatments upregulated hexadecanedioic acid abundance and the gene encoding the auxin response protein. This study provides new insights into the underlying mechanisms through which invasive plants defend against PTE exposure.