Light-stress-related changes in the properties of photosystem I

Abstract

Light-stress-related changes in photosystem I (PS I) were analyzed in photoautotrophic cultured cells of Marchantia polymorpha L. High light treatment (30 h; 1300 mol photons · m )2 · s )1 ) reduced the PS I-mediated electron-transport rate by more than 50% and the photochemical efficiency of photosystem II (PS II) by about 35%. In photoinhibited cells, 76% of the PS II centers remained closed in low light, which is in agreement with a preferential impairment of PS I. Our data indicate that excessive linear electron transport is a cause of the loss in PS I activity. Two PS I forms could be isolated by sucrose-gradient ultracentrifugation of mildly solubilized thylakoid membranes. After high-light treatment one of these forms, which showed a larger light-harvesting complex (LHC) I antenna and a specific association of LHC IIb, was enriched. The effect could be suppressed by blockage of linear electron transport. It is suggested that PS I inactivation and state transitions caused the change in PS I organisation.Abbreviations: Chl = chlorophyll; DCMU = 3-(3,4-dichlorphenyl)-1,1-dimethylurea; Fo, Fs, F′m = basal, steady-state (light) and maximum chlorophyll fluorescence yield; LHC = light-harvesting complex; PFD = photon flux density; PS I u , PS I l = upper and lower PS I-containing bands after ultracentrifugation Correspondence

Temperature/light dependent development of selective resistance to photoinhibition of photosystem I

“…Furthermore, our results indicate that the susceptibility of PSI to photoinhibition is dependent upon the developmental history of the plant. We suggest that this may in part, explain the variability in the published literature regarding the susceptibility of PSI to photoinhibition [11–16, 38–41].…”

“…In these reports, it was demonstrated that during light stress at low temperatures the maximum quantum yield of electron transport through PSI, the pool of photooxidizeable reaction center pigment of PSI (P700), and the efficiency of P700 oxidation were dramatically reduced [11–14]. Decreased levels of EPR‐detectable P700 + [10]and inhibition of PSI electron transport [15, 16]were also shown to occur in vivo under high light at ambient temperatures. Selective photoinactivation of PSI in isolated thylakoid membranes has been also reported at chilling temperatures and at 25°C in thylakoids isolated from either chilling sensitive or chilling tolerant plants [17].…”

“…The primary site of the photoinactivation of PSI at chilling temperatures in vivo appears to be the iron‐sulfur centers [20]. More recently, excessive linear electron transport has been suggested to be a primary cause of the loss in PSI activity [16].…”

Characterization of PSI recovery after chilling-induced photoinhibition in cucumber (Cucumis sativus L.) leaves

“…Although it is known that rapid photoinhibition of PSII protects PSI by reducing electron donation to P700 during high-light treatment at room temperature (25°C) or during moderate-light treatment at low temperature (4°C) (Sonoike 1995;Herrmann et al 1997;Tjus et al 1998), the interaction between PSI and PSII during recovery from chilling-induced photoinhibition was still unknown. In addition, Kudoh and Sonoike (2002) observed that during recovery process after chilling-light treatment in cucumber leaves, chlorophyll content continues to decrease and the amount of functional PSI per unit leaf area increases very slow.…”

Identification and characterization of photosystem II chlorophyll a / b binding proteins in Marchantia polymorpha L.

“…On the other hand, zeaxanthin is formed in the xanthophyll cycle and after prolonged light stress the pool size of xanthophyll cycle pigments is increased (SchaÈ fer et al 1994). Finally, we have demonstrated that light-stress treatment of M. polymorpha culture cells also results in characteristic changes in PSI organization (Herrmann et al 1997). Due to these pronounced high-light eects we decided to investigate the molecular organization of the photosynthetic apparatus in this species.…”