The secrets of calcicole species revealed

Abstract

Calcium (Ca) is an essential macronutrient for plants. It serves as a structural component of cell walls and membranes, contributes to charge balance and osmotic regulation, and participates in cellular and systemic signalling (White and Holland, 2018). However, excess Ca can be toxic. In this issue, Kotula et al. (2021) have investigated the adaptive mechanisms enabling survival of soil-indifferent Proteaceae on soils with high Ca availability. To do this, they compared pairs of congeneric species, one of which was calcifuge and the other soil indifferent, in the genera Hakea and Banksia. They observed that the mechanisms of adaptation to excess Ca included both theoretical possibilities: (i) restricted Ca uptake and translocation in the soil-indifferent Hakea by apoplasmic barriers in the root; and (ii) tolerance of large tissue Ca concentrations by sequestration in specific cell types in the shoot in the soil-indifferent Banksia.