ROS Crosstalk in Signalling Pathways

Abstract Plants have evolved complex signalling networks in order to respond to the plethora of environmental and developmental stimuli to which they are exposed. Within these networks, a diverse range of signals are integrated, allowing the plant to formulate an appropriate response to the prevailing conditions. An important feature of signalling pathways into networks is the potential for pathways to interact with each other, thereby influencing the responses observed. This is known as crosstalk. Signalling networks act through a hub and spoke model where the hub is a key determinant of the pathways that will crosstalk with one another. Reactive oxygen species (ROS) are an example of such a signalling hub that play an intrinsic role in crosstalk within plant stress signalling networks. ROS are of particular interest due to their ability to have positive or negative effects, depending on their abundance within the cell. Key Concepts Plants employ complex signalling networks in their responses to environmental and developmental stimuli, transducing a wide range of signals from the point of perception, typically via a receptor, to a diverse array of effectors. Signalling can occur via a range of intermediates (chemical, electrical or hydraulic) including well‐characterised secondary messenger compounds. Crosstalk can occur between signalling pathways when one or more of these components interact with each other. ROS are important signalling molecules, essential for plant cell homeostasis and the regulation of vital plant responses, such as reaction to abiotic and biotic stress, hormone signalling and the regulation of growth. ROS can have a positive or negative effect within a cell, acting as either a toxic by‐product of aerobic respiration within cells or essential signalling molecules through their role as an indispensable hub in plant signalling networks.