Changes in H(+)-ATP Synthase Activity, Proton Electrochemical Gradient, and pH in Pea Chloroplast Can Be Connected with Variation Potential.

Vladimir Sukhov,Lyubov Surova,Oksana Sherstneva,Ekaterina Morozova,Vladimir Vodeneev

doi:10.3389/fpls.2016.01092

Vladimir Sukhov, Lyubov Surova + Show 3 more

Open Access

https://doi.org/10.3389/fpls.2016.01092

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Abstract

Local stimulation induces generation and propagation of electrical signals, including the variation potential (VP) and action potential, in plants. Burning-induced VP changes the physiological state of plants; specifically, it inactivates photosynthesis. However, the mechanisms that decrease photosynthesis are poorly understood. We investigated these mechanisms by measuring VP-connected systemic changes in CO2 assimilation, parameters of light reactions of photosynthesis, electrochromic pigment absorbance shifts, and light scattering. We reveal that inactivation of photosynthesis in the pea, including inactivation of dark and light reactions, was connected with the VP. Inactivation of dark reactions decreased the rate constant of the fast relaxation of the electrochromic pigment absorbance shift, which reflected a decrease in the H+-ATP synthase activity. This decrease likely contributed to the acidification of the chloroplast lumen, which developed after VP induction. However, VP-connected decrease of the proton motive force across the thylakoid membrane, possibly, reflected a decreased pH in the stroma. This decrease may be another mechanism of chloroplast lumen acidification. Overall, stroma acidification can decrease electron flow through photosystem I, and lumen acidification induces growth of fluorescence non-photochemical quenching and decreases electron flow through photosystem II, i.e., pH decreases in the stroma and lumen, possibly, contribute to the VP-induced inactivation of light reactions of photosynthesis.

Highlights

Electrical signals, namely the action potential (AP), which is mainly induced by non-damaging stimuli, and the variation potential (VP), which is mainly caused by damaging stimuli, are the most likely links between stimulated and non-stimulated zones during the systemic responses of plants (Sukhov, 2016)
The VP amplitude in the leaf significantly correlated with the magnitudes of changes in the ACO2 and non-photochemical quenching (NPQ) (Table 1)
Time of beginning of VP in the leaf was significantly correlated with time of beginning of changes in the ACO2 and NPQ (Table 1)

Summary

Introduction

Local stimulation rapidly elicits systemic responses in plants (Gallé et al, 2015), including changes in gene expression (Stankovicand Davies, 1996; Fisahn et al, 2004) and phytohormone production (Dziubinska et al, 2003; Hlavácková et al, 2006; Hlavinka et al, 2012), increases in plant resistance to stressors (Retivin et al, 1997, 1999; Sukhov et al, 2014b, 2015a; Surova et al, 2016), the activation of respiration (Dziubinska et al, 1989; Filek and Koscielniak, 1997), etc. VP Influences Chloroplast’s Electrochemical Gradient described the influence of local stimuli on photosynthetic processes (Hlavácková et al, 2006; Krupenina and Bulychev, 2007; Grams et al, 2009; Pavlovicet al., 2011; Hlavinka et al, 2012; Sukhov et al, 2012, 2014a,b, 2015a,b; Vredenberg and Pavlovic, 2013; Bulychev and Komarova, 2014; Sherstneva et al, 2015, 2016; Surova et al, 2016), including reduced CO2 assimilation, decreases in the photosystem I (PSI) and photosystem II (PSII) quantum yields, the growth of fluorescence non-photochemical quenching (NPQ), and the activation of cyclic electron flow. Numerous works (Grams et al, 2009; Sukhov et al, 2014a; Sherstneva et al, 2015, 2016) have reported that the VP-connected H+ influx is a potential mechanism of photosynthetic inactivation

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