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Short-term regulation and alternative pathways of photosynthetic electron transport in Hibiscus rosa-sinensis leaves

Paper ID Volume ID Publish Year Pages File Format Full-Text
29668 44427 2015 16 PDF Available
Title
Short-term regulation and alternative pathways of photosynthetic electron transport in Hibiscus rosa-sinensis leaves
Abstract

•Induction events of photosynthetic electron transport in Hibiscus leaves were studied.•The EPR and PAM-fluorometry methods and mathematical modeling were used.•Mechanisms of electron and proton transport control are considered.•Computer model adequately describes transient kinetics of electron transport.

In this work, using the EPR and PAM-fluorometry methods, we have studied induction events of photosynthetic electron transport in Hibiscus rosa-sinensis leaves. The methods used are complementary, providing efficient tools for in situ monitoring of P700 redox transients and photochemical activity of photosystem II (PSII). The induction of P700+ in dark-adapted leaves is characterized by the multiphase kinetics with a lag-phase, which duration elongates with the dark-adaptation time. Analyzing effects of the uncoupler monensin and artificial electron carrier methylviologen (MV) on photooxidation of P700 and slow induction of chlorophyll a fluorescence (SIF), we could ascribe different phases of transient kinetics of electron transport processes in dark-adapted leaves to the following regulatory mechanisms: (i) acceleration of electron transfer on the acceptor side of PSI, (ii) pH-dependent modulation of the intersystem electron flow, and (iii  ) re-distribution of electron fluxes between alternative (linear, cyclic, and pseudocyclic) pathways. Monensin significantly decreases a level of P700+ and inhibits SIF. MV, which mediates electron flow from PSI to O2 with consequent formation of H2O2, promotes a rapid photooxidation of P700 without any lag-phase peculiar to untreated leaves. MV-mediated water–water cycle (H2O → PSII → PSI → MV → O2 → H2O2 → H2O) is accompanied by generation of ascorbate free radicals. This suggests that the ascorbate peroxidase system of defense against reactive oxygen species is active in chloroplasts of H. rosa-sinensis   leaves. In DCMU-treated chloroplasts with inhibited PSII, the contribution of cyclic electron flow is insignificant as compared to linear electron flow. For analysis of induction events, we have simulated electron transport processes within the framework of our generalized mathematical model of oxygenic photosynthesis, which takes into account pH-dependent mechanisms of electron transport control and re-distribution of electron fluxes between alternative pathways. The model adequately describes the main peculiarities of P700+ induction and dynamics of the intersystem electron transport.

Keywords
Photosynthesis; Photooxidation of P700; Induction events; Regulation of photosynthetic electron transport; Mathematical modeling
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Publisher
Database: Elsevier - ScienceDirect
Journal: Journal of Photochemistry and Photobiology B: Biology - Volume 152, Part B, November 2015, Pages 400–415
Authors
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Subjects
Physical Sciences and Engineering Chemical Engineering Bioengineering
Get Full-Text Now
Don't Miss Today's Special Offer
Price was $35.95
You save - $31
Price after discount Only $4.95
100% Money Back Guarantee
Full-text PDF Download
Online Support
Any Questions? feel free to contact us