Calcium signaling is involved in diverse cellular processes in fungi.

Calcium (Ca2+) is a universal signalling molecule of life. The Ca2+ signalling is an evolutionarily conserved process from prokaryotes to eukaryotes. Ca2+ at high concentration is deleterious to the cell; therefore, cell maintains a low resting level of intracellular free Ca2+ concentration ([Ca2+]c). The resting [Ca2+]c is tightly regulated, and a transient increase of the [Ca2+]c initiates a signalling cascade in the cell. Ca2+ signalling plays an essential role in various processes, including growth, development, reproduction, tolerance to stress conditions, and virulence in fungi. In this review, we describe the evolutionary aspects of Ca2+ signalling and cell functions of major Ca2+ signalling proteins in different fungi.