Abstract
Photosynthesis consists of two types of electron flow, linear (LET) and PSI cyclic electron transport (CET). CET is involved in both ATP synthesis and photoprotection. In higher plants, CET consists of two pathways, NDH-dependent and PGR5-dependent electron transport. Antimycin A (AA) inhibits mitochondrial electron transport and is also used as an inhibitor of PGR5-dependent CET. However, high concentration of AA is needed, causing several non-specific inhibitory effects. Furthermore, AA may not bind to the quinone-binding site of FQR, a putative enzyme involved in PGR5-dependent CET. In this study, we examined effects of a series of substituted phenols on CET activity in the wild type, and crr2-2 and pgr5 mutants, defective in NDH- and PGR5-deepndent CET, respectively. We found candidates which inhibit PGR5-dependent CET more efficiently than AA.
