Different impact of high light on the response and recovery of wild type and lut2 mutant of Arabidopsis thaliana at low temperature

Response of Pea Plants (Pisum sativum cv. Ran 1) to NaCl Treatment in Regard to Membrane Stability and Photosynthetic Activity

“…With respect to activity of PSI, a certain degree of stimulation was detected after 2 days of treatment with 100 and 150 mM NaCl. A similar stimulation of PSI-mediated electron transport was reported for the thylakoids of tomato plants treated with a high temperature and high light intensity [ 54 ] and for Arabidopsis thaliana subjected to high light at low temperature [ 38 ]. The observed stimulation could be due to the activation of a cyclic electron flow around PSI, providing additional ATP for metabolic reactions and maintaining the proton gradient across the thylakoid membrane [ 55 ].…”

“…In addition, the decrease in the A 1 /A 2 ratio indicated that the contribution of PSIIα centers to the overall evolved oxygen was gradually decreased with the elevation in NaCl concentration and duration of treatment, suggesting that these centers were stronger affected by the salt treatment in comparison with PSIIβ. Similar higher sensitivity of PSIIα centers was reported for pea plants after heat treatment and fluidity modification [ 37 ], as well as after UV treatment [ 39 ], and for Arabidopsis thaliana , wt and lut2 mutant, subjected to simultaneous treatment with high light and low temperature [ 38 ]. The kinetics of both types of centers were also affected by the salt treatment, expressed as the retardation of their turnover, as evidenced by the increase in the time constants of the “fast” PSIIα and “slow” PSIIβ centers, t 1 and t 2 , respectively.…”

“…The evaluation of the activity of the oxygen-evolving complex was performed through the detection of the oxygen flash yields and initial oxygen burst, without the addition of an electron acceptor, using home-constructed equipment with a Joliot-type oxygen electrode [ 62 ], as described in [ 38 ]. Each sample contained 100 μL of thylakoid membrane at a concentration of 300 µg Chl mL −1 .…”

“…The thylakoid membranes, at a concentration of 10 µg Chl mL −1 , were resuspended in a medium containing 0.33 M sucrose, 5 mM MgCl 2 , 10 mM NaCl and 20 mM Tricine (pH 7.5). Each sample was transferred to a quartz tube for the fluorescence measurements and immediately frozen in liquid nitrogen [ 38 ]. Fluorescence emission spectra were recorded after excitation with 436 nm to preferentially excite Chl a.…”

“…The PSIIα centers are located in the grana domains of thylakoid membranes, possess larger antenna, form dimmers and contain a functional acceptor and donor side [ 34 ], while the PSIIβ centers are situated in the stroma-exposed thylakoid lamellae, possess smaller antenna and are organized as monomers. Both types of PSII centers demonstrate different levels of sensitivity towards stress stimuli, including heat and altered fluidity [ 37 ], low temperatures [ 38 ] and UV treatment [ 39 ].…”