Effects of H₂O₂ Micropipette Application on Photosynthetic Electron Transport in Chara Chloroplasts With Unimpaired and Short-Circuited H⁺ Flows.

Authors

Natalia A Krupenina, Alexander A Bulychev, Alexander A Cherkashin

Published in

Physiologia plantarum. Volume 178. Issue 5. Pages e71156.

Abstract

Hydrogen peroxide is a byproduct of oxygenic photosynthesis. While the ways of H₂O₂ disposal in chloroplasts are mostly known, the influence of H₂O₂ on photosynthetic electron transport received less attention. According to various reports, H₂O₂ indirectly promotes electron transport on the acceptor side of photosystem I and activates cyclic electron transport (CET). Here the microinjection technique and PAM microfluorometry were applied to study the influence of H₂O₂ on linear and cyclic electron flows in internodal Chara cells. First, the cells loaded with a fluorogenic ROS-sensitive probe DCF were used to show that microinjection of H₂O₂ is followed by rapid intracellular penetration of H₂O₂ and its distribution with the streaming cytoplasm. Next, the regulatory influence of H₂O₂ on electron transport was examined in chloroplasts with unimpaired and short-circuited H⁺ flows. Linear electron transport (LET) was assessed with a Microscopy PAM fluorometer, whereas the inference on CET was based on measurements of the post-illumination rise of the chlorophyll fluorescence yield. The local application of H₂O₂ was followed by a temporary development of non-photochemical quenching (NPQ). In chloroplasts uncoupled with nigericin, the NPQ development after H₂O₂ microinjection was eliminated, while the polarity and amplitude of H₂O₂-induced F' fluorescence changes were reverted and enhanced, respectively. Post-illumination fluorescence responses (PIFR) in Chara were large and comparable in extent to changes induced by intense light. The development of PIFR after preillumination was instantly collapsed upon H₂O₂ injection, indicating that the reaction product arising in the presence of H₂O₂ redirected electron flow from the cyclic route along the competitive linear pathway.

PMID:
42893799
Bibliographic data and abstract were imported from PubMed on 19 Oct 2026.

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