Special issue in honour of Prof. Reto J. Strasser - Effect of AtLFNR1 deficiency on chlorophyll a fluorescence rise kinetics OJIP of Arabidopsis

Abstract

Leaf-type ferredoxin-NADP(H) oxidoreductase, encoded by AtLFNR1 gene in Arabidopsis, extensively exists in chloroplast stroma and thylakoids and is responsible for the reduction of NADP + to NADPH in PSI. To investigate the relationship between the characteristics of chlorophyll a fluorescence transients OJIP and the function of AtLFNR1 protein, the fluorescence rise kinetics OJIP curves of AtLFNR1 mutant leaves were determined. It is observed that AtLFNR1 mutant has a lower level of variable fluorescence intensity relative to wild type, especially the J-step and the IP-phase. The JIP-test analysis suggests that the loss of AtLFNR1 function decreases clearly the oxidation rate of plastocyanin as well as PSI reaction center, damages slightly PSII antenna size and pigment assemblies, but stimulates distinctly the photosynthetic activity of PSII. Such multiple effects contribute to the change of shape characteristics of the OJIP transient curve in AtLFNR1 mutant.

In vitro morphophysiological responses of Alternanthera tenella colla (Amaranthaceae) to stress induced by cadmium and the attenuating action of silicon

“…The association among F V /F 0 , φP 0 , and φE 0 allows analyzing the status of the electron transport system and the e ciency of the trapping, conversion, and transport of energy between the two photosystems (Strasser et al 2004;Guo et al 2020). In this respect, the presence of Cd caused a reduction of the values of φP 0 , F V /F 0 , and φE 0 in the treatment with 200 µM Cd, resulting in lower photosynthetic apparatus e ciency.…”

“…The performance indices PI (ABS) and PI (Total) indicate how the stress factors affect the performance and integrity of the photosynthetic apparatus of plants (Kalaji et al 2016). In particular, because PI (ABS) represents the combination of three factors (total number of active reaction centers for absorption of light; trapping of excitation energy; and conversion of that energy into the transport of electrons in PSII), and this parameter is sensitive to the stress caused by the metal (Martins et al 2020;Guo et al 2020). Therefore, the presence of Si reduced the damage to the system for trapping of excitation energy, resulting in a better performance of PSII, mainly at the highest Cd concentration.…”

“…The Si also acted to reduce the photodamage beyond the intersystem, mainly at the highest Cd concentration, con rmed by the increased values of PI (Total) . According to Guo et al (2020), the increase of this parameter when plants are facing high stress is an indicator of improved ability to achieve photochemical reactions, i.e., their e ciency in using the energy absorbed by the antennas for conversion into energy in the form of ATP and NADPH, resulting in better physiological conditions for development and survival.…”

“…For this purpose, the second pair of fully expanded leaves (from the tips and not detached) of 18 different plants (n = 18) from each treatment were previously adapted to the dark for 30 min with leaf clips (Hansatech ® ). The uorescence emission was induced in a circular area with a diameter of 4 mm by exposure of the sample to a saturating redlight pulse (peak 650 nm), and the intensity of 3,000 μmol m -2 s -1 was recorded and used to calculate the parameters of the JIP test and the relative variable uorescence between the steps O and P (V OP ), steps O and K (V OK ), and steps O and J (V OJ ) (Strasser et al 2004; Stirbet and Govindjee 2011; Guo et al 2020) using the Biolyzer software (Bioenergetics Laboratory, University of Geneva, Switzerland). The W L and W K were calculated according to Zhang et al (2018).…”

Photosynthetic apparatus performance and anatomical modulations of Alcantarea imperialis (Bromeliaceae) exposed to selenium during in vitro growth

“…A decline of the J-step level (VJ) can be attributed to a lower accumulation of reduced plastoquinone A (QA) electron acceptor of PSII RC. This is interpreted as a higher rate of electron flow from QA to the plastoquinone B (QB) electron acceptor of PSII RC and expressed as increased values of φE0 (Martins et al 2019, Guo et al 2020a. This lower accumulation of QA − was reflected in higher values of Sm/tFmax.…”