The Role of Basal H₂O₂ Concentration in ROS Stress Signaling Waveforms <i>In Planta</i>

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.