# Magnesium: An overlooked signalling ion in plant physiology and circadian regulation

## TL;DR

This paper reviews the role of magnesium as a signaling ion in plants, highlighting its importance in growth, metabolism, and circadian regulation.

## Contribution

The paper identifies magnesium as a potential regulatory ion with signaling properties in plants, beyond its traditional roles.

## Key findings

- Magnesium interacts with other nutrients, influencing nutrient acquisition and stress responses.
- Magnesium dynamics are linked to circadian regulation in plants.
- Magnesium may function as a signaling ion with properties similar to secondary messengers in animals.

## Abstract

Magnesium (Mg2+) is essential for plant growth and metabolism, acting as a cofactor in numerous enzymatic and structural processes. This review outlines the main physiological and biochemical functions of Mg2+ and summarizes current knowledge on its transport and homeostatic regulation. We examine how Mg2+ homeostasis intersects with broader signalling networks and metabolic pathways, including its crosstalk with other mineral nutrients, where antagonistic and synergistic interactions influence nutrient acquisition, allocation and stress responses. Emerging evidence further suggests that, beyond its classical roles, Mg2+ may function as a regulatory ion with signalling properties reminiscent of secondary messengers in animal systems. Finally, we highlight recent findings linking Mg2+ dynamics to circadian regulation, suggesting reciprocal interactions between temporal control mechanisms and nutrient fluxes. These insights underscore the central importance of Mg2+ in plant biology and identify key gaps in understanding its regulatory and integrative roles.