Lithium in plants

The physiological significance of lithium (Li⁺) remains largely unexplored in plants despite its consistent presence in at least trace concentrations in plant tissues. While Li⁺ has traditionally been associated with salinity-like stress symptoms and presumed to utilise sodium (Na⁺) transport pathways, accumulating evidence points to multiple differences in Li⁺ and Na⁺ transport and toxicity responses. Notably, the existence of a putative Li⁺-specific transporter and the poor Li⁺ permeability of some Na⁺ transporters challenge the prevailing dogma of shared transport pathways. In addition, Li⁺ specific effects on reactive oxygen species further differentiate it from being a Na⁺ analogue. Moreover, Li⁺ can strongly displace magnesium (Mg²⁺) from enzyme binding sites and also directly interact with nucleic acids, effects that have been largely overlooked in plants, but are likely to be central to its biological impact. This review provides a comprehensive synthesis of Li⁺ transport and molecular interactions, highlighting emerging concepts, knowledge gaps, and new opportunities. As global Li⁺ demand rises due to its role in batteries, understanding how plants tolerate and mobilise Li⁺ may open exciting new biotechnological applications for recycling industrial waste, phytoremediation of contaminated soils and biofortification of Li-enriched foods.