Increasing complexity and versatility: How the calcium signaling toolkit was shaped during plant land colonization

Plants and animals exhibit substantial differences in their complements of Ca2+ channels and Ca2+ binding proteins. Within the plant lineage, remarkable differences in the evolution of complexity between different families of Ca2+ signaling proteins are observable. Using the CBL/CIPK Ca2+ sensor/kinase signaling network as model, we attempt to link evolutionary tendencies to functional predictions. Our analyses, for example, suggest Ca2+ dependent regulation of Na+ homeostasis as an evolutionary most ancient function of this signaling network. Overall, gene families of Ca2+ signaling proteins have significantly increased in their size during plant evolution reaching an extraordinary complexity in angiosperms.