Consequences of photosystem‐I damage and repair on photosynthesis and carbon use in Arabidopsis thaliana

Abstract

Summary Natural growth environments commonly include fluctuating conditions that can disrupt the photosynthetic energy balance and induce photoinhibition through inactivation of the photosynthetic apparatus. Photosystem II (PSII) photoinhibition is efficiently reversed by the PSII repair cycle, whereas photoinhibited photosystem I (PSI) recovers much more slowly. In the current study, treatment of the Arabidopsis thaliana mutant proton gradient regulation 5 (pgr5) with excess light was used to compromise PSI functionality in order to investigate the impact of photoinhibition and subsequent recovery on photosynthesis and carbon metabolism. The negative impact of PSI photoinhibition on CO2 fixation was especially deleterious under low irradiance. Impaired starch accumulation after PSI photoinhibition was reflected in reduced respiration in the dark, but this was not attributed to impaired sugar synthesis. Normal chloroplast and mitochondrial metabolisms were shown to recover despite the persistence of substantial PSI photoinhibition for several days. The results of this study indicate that the recovery of PSI function involves the reorganization of the light‐harvesting antennae, and suggest a pool of surplus PSI that can be recruited to support photosynthesis under demanding conditions.

Plastidic glucose-6-phosphate dehydrogenases are regulated to maintain activity in the light

“…However, with high light, in fluctuating light (61), and at low temperature (62), excess energy or electrons could still be passed on to PSI and result in PSI photoinhibition. Unlike PSII, the proteins of PSI have a low turnover rate and damage to PSI is considered more severe than damage to PSII (62–64). Coupling ATP consumption in the G6P shunt with cyclic electron flow would dissipate light energy at PSI (65–67).…”

The unique photosynthetic apparatus of Pinaceae: analysis of photosynthetic complexes in Picea abies

“…Such flavodiiron proteins are absent from all angiosperms (Allahverdiyeva et al , 2015; Yamamoto et al , 2016; Ilík et al , 2017). Alternatively, PSI* may serve as a pool of excess PSI that can supplement photosynthetic activity under demanding conditions (Zhang and Scheller, 2004; Lima-Melo et al , 2019).…”

Photoinhibition of Photosystem I Provides Oxidative Protection During Imbalanced Photosynthetic Electron Transport in Arabidopsis thaliana

“…Under these stress conditions, reduction of O 2 produces O2•- that can inactivate PSI iron-sulfur (FeS) clusters and cause PSI inhibition (Sonoike and Terashima, 1994; Sonoike, 1995; Takagi et al, 2016; Tiwari et al, 2016). In contrast to PSII, the recovery of inhibited PSI has been shown to occur very slowly, over several days (Barth et al, 2001; Kudoh and Sonoike, 2002; Huang et al, 2010; Lima-Melo et al, 2019). PSI photoinhibition in wild type plants has been observed under low irradiance at chilling temperatures, due to down-regulation of stromal electron sinks (Inoue et al, 1986; Terashima et al, 1994; Tjus et al, 1998; Zhang and Scheller, 2004) as well as under fluctuating light (Kono et al, 2014).…”

“…Severe PSI photoinhibition can occur when pH-dependent control of electron transport is inactivated, such as in plants lacking the PGR5 protein (Munekage et al, 2002; Nandha et al, 2007; Suorsa et al, 2012; Tiwari et al, 2016). High light treatment of the pgr5 mutant of Arabidopsis thaliana has provided an inducible model for PSI inhibition that has been used to study the mechanisms of PSI damage and the impacts of PSI photoinhibition on photosynthesis and metabolism of plants (Tiwari et al, 2016; Gollan et al, 2017; Lima-Melo et al, 2019). Exposure of pgr5 to sudden increases in light intensity causes PSI FeS cluster damage (Tiwari et al, 2016) and degradation of PSI subunit proteins (Suorsa et al, 2012; Lima-Melo et al, 2019).…”