title: A deficiency in chloroplastic ferredoxin 2 facilitates effective photosynthetic capacity during long-term high light acclimation in Arabidopsis thaliana.
abstract: Photosynthetic electron transport is the major energy source for cellular metabolism in plants, and also has the potential to generate excess reactive oxygen species that cause irreversible damage to photosynthetic apparatus under adverse conditions. Ferredoxins (Fds), as the electron-distributing hub in the chloroplast, contribute to redox regulation and antioxidant defense. However, the steady-state levels of photosynthetic Fd decrease in plants when they are exposed to environmental stress conditions. To understand the effect of Fd down-regulation on plant growth, we characterized Arabidopsis thaliana plants lacking Fd2 (Fd2-KO) under long-term high light (HL) conditions. Unexpectedly, Fd2-KO plants exhibited efficient photosynthetic capacity and stable thylakoid protein complexes. At the transcriptional level, photoprotection-related genes were up-regulated more in the mutant plants, suggesting that knockout Fd2 lines possess a relatively effective photo-acclimatory responses involving enhanced plastid redox signaling. In contrast to the physiological characterization of Fd2-KO under short-term HL, the plastoquinone pool returned to a relatively balanced redox state via elevated PGR5-dependent cyclic electron flow during extended HL. fd2 pgr5 double mutant plants displayed severely impaired photosynthetic capacity under HL treatment, further supporting a role for PGR5 in adaptation to HL in the Fd2-KO plants. These results suggest potential benefits of reducing Fd levels in plants grown under long-term HL conditions.
authors.affiliation: State Key Laboratory of Biocontrol and Guangdong Key Laboratory of Plant Resources, School of Life Sciences, Sun Yat-sen University, 510275, Guangzhou, China.
authors.forename: Jun
authors.initials: J
authors.lastname: Liu
authors.forename: Peng
authors.initials: P
authors.lastname: Wang
authors.forename: Bing
authors.initials: B
authors.lastname: Liu
authors.forename: Dongru
authors.initials: D
authors.lastname: Feng
authors.forename: Jie
authors.initials: J
authors.lastname: Zhang
authors.forename: Jianbin
authors.initials: J
authors.lastname: Su
authors.forename: Yang
authors.initials: Y
authors.lastname: Zhang
authors.forename: Jin-Fa
authors.initials: JF
authors.lastname: Wang
authors.forename: Hong-Bin
authors.initials: HB
authors.lastname: Wang
mesh_terms: D000064:Acclimatization; D017360:Arabidopsis / Q000235:genetics / Q000502:physiology / Q000528:radiation effects*; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D002736:Chloroplasts / Q000378:metabolism; D005288:Ferredoxins / Q000235:genetics / Q000378:metabolism*; D055786:Gene Knockout Techniques; D008027:Light; D008969:Molecular Sequence Data; D010788:Photosynthesis / Q000502:physiology*; D045322:Photosynthetic Reaction Center Complex Proteins / Q000235:genetics / Q000378:metabolism; D013312:Stress, Physiological
chemical_list: D029681:Arabidopsis Proteins; D005288:Ferredoxins; C465062:PGR5 protein, Arabidopsis; D045322:Photosynthetic Reaction Center Complex Proteins
keywords: Arabidopsis thaliana; PGR5-dependent cyclic electron flow; ferredoxin 2 knockout; high light acclimation; photosynthetic capacity; redox signaling