AUTHOR=Kou Jiancun , Takahashi Shunichi , Fan Da-Yong , Badger Murray R., Chow Wah S.

TITLE=Partially dissecting the steady-state electron fluxes in Photosystem I in wild-type and pgr5 and ndh mutants of Arabidopsis

JOURNAL=Frontiers in Plant Science

VOLUME=6

YEAR=2015

URL=https://www.frontiersin.org/journals/plant-science/articles/10.3389/fpls.2015.00758

DOI=10.3389/fpls.2015.00758

ISSN=1664-462X

ABSTRACT=<p>Cyclic electron flux (CEF) around Photosystem I (PS I) is difficult to quantify. We obtained the linear electron flux (LEF<sub>O2</sub>) through both photosystems and the total electron flux through PS I (ETR1) in <italic>Arabidopsis</italic> in CO<sub>2</sub>-enriched air. ΔFlux = ETR1 – LEF<sub>O2</sub> is an upper estimate of CEF, which consists of two components, an antimycin A-sensitive, PGR5 (proton gradient regulation 5 protein)-dependent component and an insensitive component facilitated by a chloroplastic nicotinamide adenine dinucleotide dehydrogenase-like complex (NDH). Using wild type as well as <italic>pgr5</italic> and <italic>ndh</italic> mutants, we observed that (1) 40% of the absorbed light was partitioned to PS I; (2) at high irradiance a substantial antimycin A-sensitive CEF occurred in the wild type and the <italic>ndh</italic> mutant; (3) at low irradiance a sizable antimycin A-sensitive CEF occurred in the wild type but not in the <italic>ndh</italic> mutant, suggesting an enhancing effect of NDH in low light; and (4) in the <italic>pgr5</italic> mutant, and the wild type and <italic>ndh</italic> mutant treated with antimycin A, a residual ΔFlux existed at high irradiance, attributable to charge recombination and/or pseudo-cyclic electron flow. Therefore, in low-light-acclimated plants exposed to high light, ΔFlux has contributions from various paths of electron flow through PS I.</p>