Dynamic distribution and temporal transcriptome adaptations elucidate lithium accumulation pattern in Cardamine violifolia

Abstract

The growing use of electronic devices and power batteries has introduced lithium (Li) as a new environmental contaminant. However, knowledge on the toxicity of Li to plants remains scarce. In this study, Cardamine violifolia was exposed to 200 mg L⁻¹ of LiCl, with samples collected on 3, 6, 9, and 12 d. Results showed that Li concentration in C. violifolia increased over time. By 12 d, the shoots and roots accumulated 164.67 mg kg⁻¹ and 8.41 mg kg⁻¹ FW of Li, respectively. Li was primarily found in the blade edges and was mainly distributed in cell walls and soluble components. Activities of peroxidase (POD), superoxide dismutase (SOD), catalase (CAT), and ascorbate peroxidase (APX) enzymes were significantly increased under Li exposure. Transcriptome analysis identified 15,810 differentially expressed genes (DEGs). In the shoots, DEGs were enriched in plant hormone signal transduction, phenylpropanoid biosynthesis, and pentose and glucuronate interconversion pathways. In the roots, DEGs were mainly enriched in phagosome and ribosome pathways. Weighted gene co-expression network analysis indicated that potassium transporter 5 (HAK5), potassium transporter 9 (KT9), metal transporter (Nramp), metal-nicotianamine transporter (YSL), Glutathione S-transferase U (GSTU), potassium channel (KAT), nitrate transporter (NRT1), heavy metal-associated isoprenylated plant protein (HMA), odium/calcium exchanger (NCL), and ATP-binding cassette transporter C family member (ABCC) genes may be involved in Li uptake and transport in C. violifolia. This study systematically revealed the unique distribution patterns of Li in C. violifolia. By integrating physiological, biochemical, and transcriptomic analyses, we identified multiple gene families associated with Li transport in plants. These findings not only provide novel insights into the spatial regulatory mechanisms underlying plant responses to emerging pollutants but also establish a theoretical foundation for developing phytoremediation-based technologies for Li contamination.