Moving magnesium in plant cells

Magnesium (Mg) is among the most abundant mineral elements in plants, yet the knowledge of which genes control its accumulation in specific tissues and organelles lags behind that of many other mineral elements. Only in recent years has identification of important molecular players begun to take shape. In this issue of New Phytologist, Conn et al. (pp. 583–594) shed additional light on two Mg transporters that play important roles in accumulation of Mg in leaf cell vacuoles. Using subcellular-level ion measurements on leaves, gene expression measurements after single-cell sampling, a genetic approach, and clever use of calcium (Ca) and Mg supply to plants or detached leaves, Conn et al. have demonstrated that vacuoles of mesophyll rather than epidermal or bundle sheath cell types of Arabidopsis leaves are the main sites of Mg accumulation. They have also shown the effects of mutations in MRS2-1 and MRS2-5 genes on this accumulation and a role for these genes in plant adaptation to adverse soil environments