Abstract
Local damage (e.g., burning, heating, or crushing) causes the generation and propagation of a variation potential (VP), which is a unique electrical signal in higher plants. A VP influences numerous physiological processes, with photosynthesis and respiration being important targets. VP generation is based on transient inactivation of H+-ATPase in plasma membrane. In this work, we investigated the participation of this inactivation in the development of VP-induced photosynthetic and respiratory responses. Two- to three-week-old pea seedlings (Pisum sativum L.) and their protoplasts were investigated. Photosynthesis and respiration in intact seedlings were measured using a GFS-3000 gas analyzer, Dual-PAM-100 Pulse-Amplitude-Modulation (PAM)-fluorometer, and a Dual-PAM gas-exchange Cuvette 3010-Dual. Electrical activity was measured using extracellular electrodes. The parameters of photosynthetic light reactions in protoplasts were measured using the Dual-PAM-100; photosynthesis- and respiration-related changes in O2 exchange rate were measured using an Oxygraph Plus System. We found that preliminary changes in the activity of H+-ATPase in the plasma membrane (its inactivation by sodium orthovanadate or activation by fusicoccin) influenced the amplitudes and magnitudes of VP-induced photosynthetic and respiratory responses in intact seedlings. Decreases in H+-ATPase activity (sodium orthovanadate treatment) induced fast decreases in photosynthetic activity and increases in respiration in protoplasts. Thus, our results support the effect of H+-ATPase inactivation on VP-induced photosynthetic and respiratory responses.
Highlights
The systemic adaptation response of plants to the local action of stressors requires generation and propagation of long-distance stress signals including electrical signals
Action potential is a short-term change in the electrical potential difference across the plasma membrane including depolarization followed by repolarization; the signal is induced by non-damage stressors and actively propagates through the plant body [1,2]
We showed that the preliminary modification of H+ -ATPase activity influenced the parameters of variation potential (VP) and photosynthesis and respiration responses, its inactivation decreased the amplitude of electrical signals (Figure 3) and magnitudes of photosynthetic (Figure 4) and respiratory (Figure 7) changes
Summary
The systemic adaptation response of plants to the local action of stressors requires generation and propagation of long-distance stress signals including electrical signals. Action potential is a short-term change in the electrical potential difference across the plasma membrane including depolarization followed by repolarization; the signal is induced by non-damage stressors (cooling, touch, salts, etc.) and actively propagates through the plant body [1,2]. The mechanisms of action potential are based on both transient activation of Ca2+ , anion, and K+ channels [1,9]. System potential is long-term propagating hyperpolarization [11,12], which is possibly related to the transient activation of H+ -ATPase [11] and changes in the activity of Ca2+ and K+ channels [8,13].
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