Plants continuously have to cope with changing environmental conditions. Upon perception of biotic and abiotic stresses, such as heat or excess light, molecular warning signals propagate rapidly throughout plant tissues to trigger whole-plant defense mechanisms. Reactive oxygen species (ROS) are well-known as essential components of such systemic warning signals. However, how these ‘ROS waves’ in plants are perceived and decoded to activate defensive mechanisms remains to be elucidated. Sensing of ROS can be achieved by the oxidative modification of protein cysteine thiols, which can rapidly affect protein function and trigger downstream signaling. In this project, we will identify oxidative cysteine modifications associated with ROS waves in plant systemic stress signaling. To properly study these modifications occurring in cell-to-cell communication, we will advance and implement complementary profiling methods for cysteine oxidation within an in planta context. Obtained results will hint at putative systemic ROS protein sensors that will be functionally tested for their involvement in systemic stress signaling and acclimation. This project will be of broad relevance to stress acclimation mechanisms in other plant species and can instigate the engineering of stress tolerance in crops.