EDITORIAL

P.H. LAMBREV, T. JANDA

Photosynthetica 2023, 61(4):398-404 | DOI: 10.32615/ps.2023.044  

LHCII - a protein like a 'Swiss Army knife' with many mechanisms and functions

E. JANIK-ZABROTOWICZ, W.I. GRUSZECKI

Photosynthetica 2023, 61(4):405-416 | DOI: 10.32615/ps.2023.025  

The review highlights the relationship between the molecular organization of the light-harvesting complex of photosystem II (LHCII) and sunlight utilization by higher plants. The molecular form of LHCII switches rapidly and reversibly during diurnal changes of light intensity, from low (ca. 10) to high [ca. 1,000 µmol(photon) m^-2 s^-1], so the sensitivity of LHCII to light may control the balance between light harvesting and photoprotection state. Our understanding and concept of this mechanism are based on the knowledge of the structure and photophysics of different LHCII molecular forms: monomer, dimer, trimer,...

Single-cell microfluidics in combination with chlorophyll a fluorescence measurements to assess the lifetime of the Chlamydomonas PSBO protein

E. SZÉLES, S. KUNTAM, A. VIDAL-MEIRELES, V. NAGY, K. NAGY, Á. ÁBRAHÁM, L. KOVÁCS, S.Z. TÓTH

Photosynthetica 2023, 61(4):417-424 | DOI: 10.32615/ps.2023.028  

PSBO is an essential subunit of the oxygen-evolving complex and we recently demonstrated that its lifetime depends on environmental conditions in Chlamydomonas reinhardtii. To assess PSBO lifetime with a high time resolution, we employed (1) a microfluidic platform enabling the trapping of single cells and the parallel measurement of photosynthetic activity, and (2) a nitrate-inducible PSBO amiRNA line. Our microfluidic platform allowed the rapid replacement of the nutrient solution necessary for induction. It also enabled the precise monitoring of the decline in the F_v/F_m value, reflecting PSBO loss....

Influence of reduced amounts of sulfoquinovosyl diacylglycerol on the thylakoid membranes of the diatom Thalassiosira pseudonana

T. LIEBISCH, M. BAŞOGLU, S. JÄGER, C. BÜCHEL

Photosynthetica 2023, 61(4):425-431 | DOI: 10.32615/ps.2023.032  

Diatom thylakoids contain much higher amounts of sulfoquinovosyl diacylglycerol (SQDG) than vascular plants and the hypothesis was brought forward that this relates to their special thylakoid structure. To test this hypothesis we created knock-down mutants in Thalassiosira pseudonana that exhibited a decreased SQDG content per cell. Surprisingly, the ratio between the different lipid classes did not change, pointing to strict regulation of thylakoid lipid composition. The antenna proteins, fucoxanthin-chlorophyll proteins (FCP), were reduced and photosystem (PS) I compared to PSII was increased as judged from absorbance spectra. CD spectroscopy...

Priming of Pisum sativum seeds with stabilized Pluronic P85 nanomicelles: effects on seedling development and photosynthetic function

S. KRUMOVA, A. PETROVA, D. KOLEVA, S. PETROVA, S. STOICHEV, N. PETROVA, T. TSONEV, P. PETROV, V. VELIKOVA

Photosynthetica 2023, 61(4):432-440 | DOI: 10.32615/ps.2023.033  

Natural and synthetic polymers are widely explored for improving seed germination and plant resistance to environmental constraints. Here, for the first time, we explore stabilized nanomicelles composed of the biocompatible triblock co-polymer Pluronic P85 (SPM) as a priming agent for Pisum sativum (var. RAN-1) seeds. We tested a wide concentration range of 0.04-30 g(SPM) L^-1. Applying several structural and functional methods we revealed that the utilized nanomicelles can positively affect root length, without any negative effects on leaf anatomy and photosynthetic efficiency at 0.2 g L^-1, while strong negative...

The impact of physiologically relevant temperatures on physical properties of thylakoid membranes: a molecular dynamics study

B. FEHÉR, I.K. VOETS, G. NAGY

Photosynthetica 2023, 61(4):441-450 | DOI: 10.32615/ps.2023.035  

Thylakoid membranes are energy-converting membranes with a unique lipid composition. Though the membranes are primarily composed of proteins, their photosynthetic function is strongly influenced by the lipid constituents. Here we characterize, with molecular dynamics (MD) simulations, lipid bilayers with compositions representative of plant thylakoid membranes. We determine, in a wide range of temperatures, the physical parameters of the model membranes which are relevant for the photosynthetic function. We found a marked impact of temperature on membrane permeability due to a combination of increased compressibility and curvature of the membrane...

Growth light substantially affects both primary and secondary metabolic processes in Catharanthus roseus plants

F. GHOLIZADEH, É. DARKÓ, K. BENCZÚR, K.Á. HAMOW, M. DERNOVICS, K. NAGY, T. JANDA, M.R. RADY, G. GOHARI, M. PÁL, V.N. LE, G. SZALAI

Photosynthetica 2023, 61(4):451-460 | DOI: 10.32615/ps.2023.037  

Common periwinkle (Catharanthus roseus L.) is an important medicinal plant used by the pharmaceutical industry. The present work aimed to determine the effect of low light intensity on the primary and secondary metabolic processes, using various photosynthesis and targeted and untargeted analytical techniques. Growth light had only limited effects on the photosynthetic electron transport processes, although membrane stability seemed slightly higher in plants growing under higher light conditions. The reduced growth light caused a reduction in certain primary metabolites, including amino acids and sugars, and it also reduced the contents of...

In appreciation of an ingenious scientist and a great friend: Győző Garab

G. GOVINDJEE

Photosynthetica 2023, 61(4):461-464 | DOI: 10.32615/ps.2023.040  

To express my appreciation of Győző Garab, I describe below our association over the years, followed by a brief description of his fundamental research in the area of biophysics of photosynthesis.

Photosynthetic reaction center/graphene bio-hybrid for low-power optoelectronics

J. VUJIN, T. SZABÓ, R. PANAJOTOVIC, A.G. VÉGH, L. RINYU, L. NAGY

Photosynthetica 2023, 61(4):465-472 | DOI: 10.32615/ps.2023.041  

Photosynthetic reaction center (pRC) purified from Rhodobacter sphaeroides 2.4.1 purple bacteria was deposited on a graphene carrier exfoliated from the liquid phase and layered on the surface of SiO₂/Si substrate for optoelectronic application. Light-induced changes in the drain-source current vs. gate voltage are demonstrated. Dried photosynthetic reaction centers/graphene composite on SiO₂/Si shows a photochemical/-physical activity, as a result of interaction with the current flow in the graphene carrier matrix. The current changes are sensitive to light, due to the contribution from the charge separation in...

Monitoring the photosynthetic activity at single-cell level in Haematococcus lacustris

P.P. PATIL, K. NAGY, Á. ÁBRAHÁM, I. VASS, M. SZABÓ

Photosynthetica 2023, 61(4):473-482 | DOI: 10.32615/ps.2023.042  

Haematococcus lacustris is an important species of green algae because it produces the high-value carotenoid astaxanthin. Astaxanthin production is enhanced by various stress conditions causing the transformation of green vegetative cells to red cells with high amounts of astaxanthin, which plays various photoprotective and antioxidant roles. Although intensive research has been conducted to reveal the regulation of astaxanthin production, the photosynthetic capacity of the various cell forms is unresolved at the single-cell level. In this work, we characterized the photosynthetic and morphological changes of Haematococcus cells, using a combination...

Microdomains heterogeneity in the thylakoid membrane proteins visualized by super-resolution microscopy

R. KAŇA, B. ŠEDIVÁ, O. PRÁŠIL

Photosynthetica 2023, 61(4):483-491 | DOI: 10.32615/ps.2023.043  

The investigation of spatial heterogeneity within the thylakoid membrane (TM) proteins has gained increasing attention in photosynthetic research. The recent advances in live-cell imaging have allowed the identification of heterogeneous organisation of photosystems in small cyanobacterial cells. These sub-micrometre TM regions, termed microdomains in cyanobacteria, exhibit functional similarities with granal (Photosystem II dominant) and stromal (Photosystem I dominant) regions observed in TM of higher plants. This study delves into microdomain heterogeneity using super-resolution Airyscan-based microscopy enhancing resolution to approximately ~125...