Superoxide and Singlet Oxygen Produced within the Thylakoid Membranes Both Cause Photosystem I Photoinhibition  . Issue 3 (2nd March 2016)

• Record Type: Journal Article
• Authors: Takagi, Daisuke; Takumi, Shigeo; Hashiguchi, Masaki; Sejima, Takehiro; Miyake, Chikahiro
• Is Part Of: Plant physiology. Volume 171:Issue 3(2016)
• Page Start: 1626
• Page End: 1634
• Publication Date: 2016-03-02
• Subjects: Plant physiology -- Periodicals; Botany -- Periodicals; Periodicals; Electronic journals; 571.2
• DOI: 10.1104/pp.16.00246
• Languages: English
• ISSNs: 0032-0889

Abstract

Abstract : Repetitive short-pulse illumination produces both superoxide and singlet oxygen within the thylakoid membranes, leading to inactivation of photosystem I. Abstract: Photosystem I (PS I) photoinhibition suppresses plant photosynthesis and growth. However, the mechanism underlying PS I photoinhibition has not been fully clarified. In this study, in order to investigate the mechanism of PS I photoinhibition in higher plants, we applied repetitive short-pulse (rSP ) illumination, which causes PS I-specific photoinhibition in chloroplasts isolated from spinach leaves. We found that rSP treatment caused PS I photoinhibition, but not PS II photoinhibition in isolated chloroplasts in the presence of O2 . However, chloroplastic superoxide dismutase and ascorbate peroxidase activities failed to protect PS I from its photoinhibition. Importantly, PS I photoinhibition was largely alleviated in the presence of methyl viologen, which stimulates the production of reactive oxygen species (ROS ) at the stromal region by accepting electrons from PS I, even under the conditions where CuZn-superoxide dismutase and ascorbate peroxidase activities were inactivated by KCN. These results suggest that the ROS production site, but not the ROS production rate, is critical for PS I photoinhibition. Furthermore, we found that not only superoxide (O2 − ) but also singlet oxygen ( 1 O2 ) is involved in PS I photoinhibition induced by rSP treatment. From these results, we suggest that PS I photoinhibition is caused by both O2 − and 1 O2 produced within the thylakoid membranes when electron carriers in PS I become highly reduced. Here, we show, to our knowledge, new insight into the PS I photoinhibition in higher plants.