Exogenous Abscisic Acid Can Influence Photosynthetic Processes in Peas through a Decrease in Activity of H+-ATP-ase in the Plasma Membrane

Abstract

Abscisic acid (ABA) is an important hormone in plants that participates in their acclimation to the action of stressors. Treatment by exogenous ABA and its synthetic analogs are a potential way of controlling the tolerance of agricultural plants; however, the mechanisms of influence of the ABA treatment on photosynthetic processes require further investigations. The aim of our work was to investigate the participation of inactivation of the plasma membrane H+-ATP-ase on the influence of ABA treatment on photosynthetic processes and their regulation by electrical signals in peas. The ABA treatment of seedlings was performed by spraying them with aqueous solutions (10−5 M). The combination of a Dual-PAM-100 PAM fluorometer and GFS-3000 infrared gas analyzer was used for photosynthetic measurements; the patch clamp system on the basis of a SliceScope Pro 2000 microscope was used for measurements of electrical activity. It was shown that the ABA treatment stimulated the cyclic electron flow around photosystem I and decreased the photosynthetic CO2 assimilation, the amplitude of burning-induced electrical signals (variation potentials), and the magnitude of photosynthetic responses relating to these signals; in contrast, treatment with exogenous ABA increased the heat tolerance of photosynthesis. An investigation of the influence of ABA treatment on the metabolic component of the resting potential showed that this treatment decreased the activity of the H+-ATP-ase in the plasma membrane. Inhibitor analysis using sodium orthovanadate demonstrated that this decrease may be a mechanism of the ABA treatment-induced changes in photosynthetic processes, their heat tolerance, and regulation by electrical signals.

Inactivation of H+-ATPase Participates in the Influence of Variation Potential on Photosynthesis and Respiration in Peas

“…The transient inactivation of H + -ATPase in the plasma membrane, which is the main action of VPs [ 1 , 2 , 3 , 4 , 5 , 6 ], is a potential reason for these pH changes [ 39 , 51 , 60 ]. However, alternative mechanisms of pH changes, including anion [ 9 , 58 ] and K + [ 57 ] effluxes, are also probable.…”

“…In contrast, its activation can increase the magnitude of VP-induced changes in A CO2 . Second, the VP amplitudes and magnitudes of photosynthetic and respiratory responses are linearly related to the magnitudes of the metabolic component of the resting potential, which demonstrates the activity of H + -ATPase [ 60 , 61 ] ( Figure 2 e, Figure 5 and Figure 7 b). Third, the injection of a H + -ATPase inhibitor (OV) into a suspension of pea protoplasts induced photosynthetic and respiratory changes ( Figure 8 and Figure 9 ) that were similar to changes induced by VP.…”

“…Plants 2020, 9, 1585 3 of 21 Figure 1 shows the influence of the preliminary treatment by 0.5 mM sodium orthovanadate (OV) and 1 µM fusicoccin (FC) on the metabolic component of the resting potential in the cells of pea seedling leaves. The magnitude of the metabolic component was used to estimate the activity of H + -ATPase in the plasma membrane [60,61] because this transporter is the main mechanism through which ions are actively transported in higher plants [55,56]. Figure 1 shows the influence of the preliminary treatment by 0.5 mM sodium orthovanadate (OV) and 1 µM fusicoccin (FC) on the metabolic component of the resting potential in the cells of pea seedling leaves.…”

“…Thus, the hypothesized key role of the inactivation of H + -ATPase in the induction of photosynthetic and respiratory responses caused by electrical signals requires further investigations. Our earlier work [ 60 ] preliminarily showed that decreases in the activity of H + -ATPase influenced photosynthetic CO 2 assimilation and its response induced by VP; this study was devoted to further analyzing the participation of changes in H + -ATPase activity in forming VP-induced photosynthetic and respiratory responses in peas.…”

A Theoretical Analysis of Relations between Pressure Changes along Xylem Vessels and Propagation of Variation Potential in Higher Plants

“…It is known that electrical signals are likely to influence numerous physiological processes in plants [ 1 , 2 , 3 , 4 ], including activation of the expression of defense genes [ 12 , 13 , 14 ] and production of stress phytohormones [ 14 , 15 , 16 , 17 , 18 ]; increase in the respiratory rate [ 19 , 20 , 21 ] and ATP content of leaves [ 22 ]; changes in transpiration [ 23 , 24 , 25 ], water content [ 26 ], and photosynthetic processes [ 27 , 28 , 29 , 30 , 31 , 32 ]; and suppression of phloem mass flow [ 33 , 34 ] and plant growth [ 35 ]. There are several arguments supporting the participation of electrical signals in the induction of physiological changes after local actions of stressors.…”