Participation of intracellular and extracellular pH changes in photosynthetic response development induced by variation potential in pumpkin seedlings

Abstract

Electrical signals presented in plants by action potential and by variation potential (VP) can induce a reversible inactivation of photosynthesis. Changes in the intracellular and extracellular pH during VP generation are a potential mechanism of photosynthetic response induction; however, this hypothesis requires additional experimental investigation. The purpose of the present work was to analyze the influence of pH changes on induction of the photosynthetic response in pumpkin. It was shown that a burning of the cotyledon induced VP propagation into true leaves of pumpkin seedlings inducing a decrease in the photosynthetic CO2 assimilation and an increase in non-photochemical quenching of fluorescence, whereas respiration was activated insignificantly. The photosynthetic response magnitude depended linearly on the VP amplitude. The intracellular and extracellular concentrations of protons were analyzed using pH-sensitive fluorescent probes, and the VP generation was shown to be accompanied by apoplast alkalization (0.4 pH unit) and cytoplasm acidification (0.3 pH unit). The influence of changes in the incubation medium pH on the non-photochemical quenching of fluorescence of isolated chloroplasts was also investigated. It was found that acidification of the medium stimulated the non-photochemical quenching, and the magnitude of this increase depended on the decrease in pH. Our results confirm the contribution of changes in intracellular and extracellular pH to induction of the photosynthetic response caused by VP. Possible mechanisms of the influence of pH changes on photosynthesis are discussed.

Analysis of Light-Induced Changes in the Photochemical Reflectance Index (PRI) in Leaves of Pea, Wheat, and Pumpkin Using Pulses of Green-Yellow Measuring Light

“…Seedlings of pea (Pisum sativum L., cultivar "Albumen"), wheat (Triticum aestivum L., cultivar "Zlata"), and pumpkin (Cucurbita pepo L., cultivar "Mozoleevskaya") were used as objects in our investigation, since these are important agricultural plants with photosynthetic parameters, which were investigated in our previous works [15,18,[23][24][25][26][27]. These plants were cultivated in a Binder KBW 240 plant growth chamber (BinderGmbH, Tuttlingen, Germany) at 24 • C under a 16/8 h (light/dark) photoperiod.…”

Connection of the Photochemical Reflectance Index (PRI) with the Photosystem II Quantum Yield and Nonphotochemical Quenching Can Be Dependent on Variations of Photosynthetic Parameters among Investigated Plants: A Meta-Analysis

“…can reveal a new field for use of the photochemical reflectance index. In particular, PRI can potentially be used for fast and remote investigations of systemic photosynthetic responses induced by long-distance stress signals, including electrical [140][141][142][143][144][145][146][147], hydraulic [148], and Reactive Oxygen Species (ROS) [149] signals which strongly influence photosynthetic processes (e.g., the nonphotochemical quenching).…”

Variation potential propagation decreases heat-related damage of pea photosystem I by 2 different pathways

“…8,[10][11][12][13] VP-induced response is caused by changes in intra-and extracellular pH that is concomitant with VP generation. [14][15][16] pH-dependent decrease of HCO 3 :CO 2 ratio, 16 changes in aquaporin permeability, 12 and (or) changes in carbonic anhydrase activity 14 are potential mechanisms by which VP influences dark stage photosynthesis.…”