A qualitative analysis of the regulation of cyclic electron flow around photosystem I from the post-illumination chlorophyll fluorescence transient in Arabidopsis: a new platform for the in vivo investigation of the chloroplast redox state

• Published in: Photosynthesis research 2010-02, Vol.103 (2), p.111-123
• Main Authors: Gotoh, Eiji, Matsumoto, Masayoshi, Ogawa, Ken’ichi, Kobayashi, Yoshichika, Tsuyama, Michito
• Format: Article
• Language: English
• Subjects: Arabidopsis - enzymology; Arabidopsis - metabolism; Arabidopsis - radiation effects; Arabidopsis thaliana; Biochemistry; Biomedical and Life Sciences; Chlorophyll; Chlorophyll - metabolism; Chloroplasts; Chloroplasts - metabolism; Chloroplasts - radiation effects; Electron Transport - radiation effects; Electrons; Ferredoxins - metabolism; Flowers & plants; Fluorescence; Fructose; Fructose-Bisphosphate Aldolase - antagonists & inhibitors; Fructose-Bisphosphate Aldolase - metabolism; Immunoblotting; Investigations; Life Sciences; Light; Mutation - genetics; NADPH Dehydrogenase - metabolism; Oxidation-Reduction - radiation effects; Photosynthesis; Photosystem I Protein Complex - metabolism; Plant Genetics and Genomics; Plant Physiology; Plant Sciences; Plastoquinone - metabolism; Regular Paper
• ISSN: 0166-8595; 1573-5079
• DOI: 10.1007/s11120-009-9525-0

A transient in chlorophyll fluorescence after cessation of actinic light illumination, which has been ascribed to electron donation from stromal reductants to plastoquinone (PQ) by the NAD(P)H-dehydrogenase (NDH) complex, was investigated in Arabidopsis thaliana . The transient was absent in air in a mutant lacking the NDH complex ( ndhM ). However, in ndhM , the transient was detected in CO 2 -free air containing 2% O 2 . To investigate the reason, ndhM was crossed with a pgr5 mutant impaired in ferredoxin (Fd)-dependent electron donation from NADPH to PQ, which is known to be redundant for NDH-dependent PQ reduction in the cyclic electron flow around photosystem I (PSI). In ndhM pgr5 , the transient was absent even in CO 2 -free air with 2% O 2 , demonstrating that the post-illumination transient can also be induced by the Fd- (or PGR5)-dependent PQ reduction. On the other hand, the transient increase in chlorophyll fluorescence was found to be enhanced in normal air in a mutant impaired in plastid fructose-1,6-bisphosphate aldolase (FBA) activity. The mutant, termed fba3-1 , offers unique opportunities to examine the relative contribution of the two paths, i.e., the NDH- and Fd- (or PGR5)-dependent paths, on the PSI cyclic electron flow. Crossing fba3-1 with either ndhM or pgr5 and assessing the transient suggested that the main route for the PSI cyclic electron flow shifts from the NDH-dependent path to the Fd-dependent path in response to sink limitation of linear electron flow.