The integration of reactive oxygen species (ROS) and calcium signalling in abiotic stress responses

Reactive oxygen species (ROS) and calcium (Ca2+) signalling are interconnected in the perception and transmission of environmental signals that control plant growth, development and defence. The concept that systemically propagating Ca2+ and ROS waves function together with electric signals in directional cell‐to‐cell systemic signalling and even plant‐to‐plant communication, is now firmly imbedded in the literature. However, relatively few mechanistic details are available regarding the management of ROS and Ca2+ signals at the molecular level, or how synchronous and independent signalling might be achieved in different cellular compartments. This review discusses the proteins that may serve as nodes or connecting bridges between the different pathways during abiotic stress responses, highlighting the crosstalk between ROS and Ca2+ pathways in cell signalling. We consider putative molecular switches that connect these signalling pathways and the molecular machinery that achieves the synergistic operation of ROS and Ca2+ signals. Summary Statement The systemic transmission of information from the environment, which is crucial to plant growth and resilience, involves interconnected waves of reactive oxygen species (ROS) and calcium (Ca2+) signals that transmit information from the point of origin throughout the plant to regulate growth, development and defence. This review considers the mechanisms and proteins that co‐ordinate ROS and Ca2+ signalling processes to allow both synchronous and independent signalling in different cellular compartments. We consider the putative molecular switches that connect these the signalling pathways.