A pronounced light-induced zeaxanthin formation accompanied by an unusually slight increase in non-photochemical quenching: A study with barley leaves treated with methyl viologen at moderate light

Effect of chilling on photosynthesis and antioxidant enzymes in Hevea brasiliensis Muell. Arg.

“…It is known that chilling can induce water loss because cold reduces root hydraulic conductivity and substantially inhibits water uptake from the soil (Améglio et al 1990;Cochard et al 2000;Wilkinson et al 2001). The decrease of photochemical efficiency of photosystem (PS) II (F v /F m ) in PB260 indicates the reduced capacity of PS II to utilize incident light (Jung et al 1998). During the first day of chilling treatment, F v /F m ratio was slightly affected (at 1 and 7 h, F v /F m still represented 88 and 83% of the initial value, respectively), while the net photosynthetic rate was drastically decreased (60-70% of decrease after 1-7 h), showing that chilling temperatures inhibit the net photosynthetic rate more than the photochemical activities.…”

Effects of controlled oxidative stress and uncouplers on primary photosynthetic processes in vegetative cells of Antarctic alga Zygnema sp.

“…After 2 h of exposition to MV, NPQ was still substantially higher than in control indicating that PS II was still under stress and protective non-photochemical processes were necessary. Such behavior can be supported by the study made on barley (Kotabová et al 2008) that reports 10 mol MV-induced increase in NPQ that was attributed to violaxanthin to zeaxanthin conversion. Antioxidative response of chloroplastic photosynthetic apparatus to MV is, however, a complex matter since both inhibition and no change in antioxidative enzymes activity is reported (Kotabová et al 2008).…”

“…Such behavior can be supported by the study made on barley (Kotabová et al 2008) that reports 10 mol MV-induced increase in NPQ that was attributed to violaxanthin to zeaxanthin conversion. Antioxidative response of chloroplastic photosynthetic apparatus to MV is, however, a complex matter since both inhibition and no change in antioxidative enzymes activity is reported (Kotabová et al 2008). Similarly to NPQ, qF 0 showed increased values in MVtreated Zygnema than in control.…”

Systematic Analysis of Superoxide‐Dependent Signaling in Plant Cells: Usefulness and Specificity of Methyl Viologen Application

“…Only under stress imposed for instance by cadmium was the compensation insufficient and root growth was strongly inhibited in the PRXIIF knockout plants [64]. Methyl viologen (1,1'-dimethyl-4,4'-bipyridylium dichloride), also known as paraquat, is a quaternary nitrogen compound that is routinely used as an effector in oxidative stress research and during characterization of the antioxidative network in plants [65][66][67]. Chemically, this substance belongs to the class of viologens or bipyridylium compounds and was first described by Weidel and Russo in 1882 [68].…”

“…Its production mainly takes place in the chloroplast, while methyl viologen reactivity in the plant mitochondrion is considered to be low [86,127]. The site-specificity of O 2 À generation in the chloroplast is of use for a high number of studies employing methyl viologen as an efficient mediator of oxidative stress [65][66][67][101][102][103][104]. However, thorough discrimination between signaling events remains a critical issue to enable the precise assignment of signaling processes to specific ROS.…”