The Role of Basal H2O2 Concentration in ROS Stress Signaling Waveforms In Planta

In response to stress, living plants propagate a chemical wave composed of H₂O₂ through their tissues. Advances in nanosensors capable of measuring H₂O₂ within the living plant in real time have informed a quantitative theory to describe the spatiotemporal profile of its concentration─labeled a signaling waveform. A heretofore unaddressed aspect of the theory is the role of the existing basal H₂O₂ concentration level within the plant before and after stress wave propagation, potentially informing mechanisms of stress priming─or state changes associated with prior, low magnitude levels of stress that condition the resulting waveform. Herein, we develop a mathematical description of wave propagation within an existing basal level of H₂O₂. We show that the shape and intensity of the waveform can be mathematically decoupled from the basal H₂O₂ concentration. This opens the possibility that the equilibrium basal concentration can operate as a distinct, orthogonal signaling channel, separate from the acute waveform following a discrete stress event. The mathematics developed herein may find utility in a more detailed description of mechanisms such as stress priming. More broadly, the results will aid in extending waveform analysis across diverse plant species and environmental conditions.