Jack of all trades: Reactive oxygen species in plant responses to stress combinations and priming-induced stress tolerance

Abstract Climate change is expected to increase the frequency of heat waves, drought periods and flooding events, thereby posing a serious risk to crop productivity and global food security. In order to develop strategies to improve plant growth under adverse environmental conditions, in-depth molecular knowledge on plant stress responses is required. In this context, particular attention should be paid to the involvement of reactive oxygen species (ROS), molecules known for causing oxidative damage, but also indispensable for intra- and intercellular signal transduction required for plant acclimation to a wide variety of stress conditions. As plants often encounter multiple stressors simultaneously and their responses to these conditions can generally not be predicted based on the effects of the individual stress factors, the first part of this review focuses on the involvement of ROS and cellular redox homeostasis in plant responses to combined and multifactorial stress conditions. The second part of this work provides an overview of the role of ROS in priming strategies aimed at improving plant tolerance to climate change-related stress conditions. Finally, approaches to advance our understanding of redox dynamics in plant responses to combined stress and priming are discussed.