Chlorophyll fluorescence kinetic analysis has become an important tool in basic and applied research on plant physiology and agronomy. While early systems recorded the integrated kinetics of a selected spot or plant, later systems enabled imaging of at least the slower parts of the kinetics (20-ms time resolution). For faster events, such as the rise from the basic dark-adapted fluorescence yield to the maximum (OJIP transient), or the fluorescence yield decrease during reoxidation of plastoquinone A after a saturating flash, integrative systems are used because of limiting speed of the available imaging systems. In our new macroscopic and microscopic systems, the OJIP or plastonique A reoxidation fluorescence transients are directly imaged using an ultrafast camera. The advantage of such systems compared to nonimaging measurements is the analysis of heterogeneity of measured parameters, for example between the photosynthetic tissue near the veins and the tissue further away from the veins. Further, in contrast to the pump-and-probe measurement, direct imaging allows for measuring the transition of the plant from the dark-acclimated to a light-acclimated state via a quenching analysis protocol in which every supersaturating flash is coupled to a measurement of the fast fluorescence rise. We show that pump-and-probe measurement of OJIP is prone to artifacts, which are eliminated with the direct measurement. The examples of applications shown here, zinc deficiency and cadmium toxicity, demonstrate that this novel imaging platform can be used for detection and analysis of a range of alterations of the electron flow around PSII.

• MeSH
• Arabidopsis cytologie   metabolismus   MeSH
• Brassicaceae cytologie   účinky léků   metabolismus   MeSH
• chlorofyl chemie   metabolismus   MeSH
• design vybavení MeSH
• fluorescence MeSH
• fluorescenční mikroskopie přístrojové vybavení   metody   MeSH
• fotosyntéza MeSH
• Glycine max cytologie   účinky léků   metabolismus   MeSH
• kinetika MeSH
• listy rostlin cytologie   MeSH
• mezofylové buňky metabolismus   MeSH
• plastochinon metabolismus   MeSH
• zinek metabolismus   MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• chlorofyl MeSH
• plastochinon MeSH
• zinek MeSH

The JIP test, based on fast chlorophyll fluorescence (ChlF) kinetics and derived parameters, is a dependable tool for studying photosynthetic efficiency under varying environmental conditions. We extracted additional information from the whole OJIP and the normalized variable fluorescence (Vt) transient curve using first and second-order derivatives to visualize and localize points of landmark events. To account for light-induced variations in the fluorescence transient, we present a time-adjusted JIP test approach in which the derivatives of the transient curve are used to determine the exact timing of the J and I steps instead of fixed time points. We compared the traditional JIP test method with the time-adjusted method in analyzing fast ChlF measurements of silver birch (Betula pendula) in field conditions studying diurnal and within-crown variation. The time-adjusted JIP test method showed potential for studying ChlF dynamics, as it takes into account potential time shifts in the occurrence of J and I steps. The exact occurrence times of J and I steps and other landmark events coincided with the times of significant differences in fluorescence intensity. Chlorophyll fluorescence parameters were linearly related to photosynthetic photon flux density (PPFD) at different times of day, and the values obtained by the time-adjusted JIP test showed a stronger linear regression than the traditional JIP test. For fluorescence parameters having significant differences among different times of day and crown layers, the time-adjusted JIP test resulted in more clear differences than the traditional JIP test. Diurnal ChlF intensity data indicated that differences between the southern and northern provenance were only evident under low light conditions. Taken together, our results emphasize the potential relevance of considering the time domain in the analysis of the fast ChlF induction.

• Klíčová slova
• Betula pendula, Chlorophyll fluorescence, Diurnal variation, JIP test, Photosynthesis, Within-tree variation,
• MeSH
• bříza * MeSH
• chlorofyl MeSH
• fluorescence MeSH
• fotosyntéza MeSH
• listy rostlin MeSH
• stromy * MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• chlorofyl MeSH

• Publikační typ
• tisková chyba MeSH

Large amounts of antibiotics and microplastics are used in daily life and agricultural production, which affects not only plant growth but also potentially the food safety of vegetables and other plant products. Fast detection of the presence of antibiotics and microplastics in leafy vegetables is of great interest to the public. In this work, a method was developed to detect sulfadiazine and polystyrene, commonly used antibiotics and microplastics, in vegetables by measuring and modeling photosystem II chlorophyll a fluorescence (ChlF) emission from leaves. Chrysanthemum coronarium L., a common beverage and medicinal plant, was used to verify the developed method. Scanning electron microscopy, transmission electron microscopy, and liquid chromatograph-mass spectrometer analysis were used to show the presence of the two pollutants in the samples. The developed kinetic model could describe measured ChlF variations with an average relative error of 0.6%. The model parameters estimated for the chlorophyll a fluorescence induction kinetics curve (OJIP) induction can differentiate the two types of stresses while the commonly used ChlF OJIP induction characteristics cannot. This work provides a concept to detect antibiotic pollutants and microplastic pollutants in vegetables based on ChlF.

• Klíčová slova
• OJIP transients, antibiotics, food security, microplastics, modeling, vegetable quality detection,
• Publikační typ
• časopisecké články MeSH

Lichens are symbiotic organisms that are well adapted to desiccation/rehydration cycles. Over the last decades, the physiological background of their photosynthetic response-specifically activation of the protective mechanism during desiccation-has been studied at the level of photosystem II of the lichen photobiont by means of several biophysical methods. In our study, the effects of desiccation and low temperatures on chlorophyll fluorescence and spectral reflectance parameters were investigated in Antarctic chlorolichen Dermatocarpon polyphyllizum. Lichen thalli were collected from James Ross Island, Antarctica, and following transfer to a laboratory, samples were fully hydrated and exposed to desiccation at temperatures of 18, 10, and 4 °C. During the desiccation process, the relative water content (RWC) was measured gravimetrically and photosynthetic parameters related to the fast transient of chlorophyll fluorescence (OJIP) were measured repeatedly. Similarly, the change in spectral reflectance parameters (e.g., NDVI, PRI, G, NPCI) was monitored during thallus dehydration. The dehydration-response curves showed a decrease in a majority of the OJIP-derived parameters (e.g., maximum quantum yield of photosystem II photochemistry: FV/FM, and performance index: PI in D. polyphyllizum, which were more apparent at RWCs below 20%. The activation of protective mechanisms in severely dehydrated thalli was documented by increased thermal dissipation (DI0/RC) and its quantum yield (Phi_D0). Low temperature accelerated these processes. An analysis of the OJIP shape reveals the presence of K-bands (300 μs), and L-bands (80 μs), which can be attributed to dehydration-induced stress. Spectral reflectance indices decreased in a majority of cases with an RWC decrease and were positively related to the OJIP-derived parameters: FV/FM (capacity of photosynthetic processes in PSII), Phi_E0 (effectiveness of electron transport), and PI_tot (total performance index), which was more apparent in NDVI. A negative relation was found for NPCI. These indices could be used in follow-up ecophysiological photosynthetic studies of lichens that are undergoing rehydration/dehydration cycles.

• Klíčová slova
• Fast chlorophyll fluorescence curve, OJIP, Spectral reflectance, Stress, Upper cortex,
• MeSH
• Ascomycota fyziologie   MeSH
• dehydratace MeSH
• fotosyntéza * MeSH
• fotosystém II (proteinový komplex) metabolismus   MeSH
• fyziologická adaptace * MeSH
• lišejníky fyziologie   MeSH
• nízká teplota MeSH
• voda fyziologie   MeSH
• vysoušení MeSH
• Publikační typ
• časopisecké články MeSH
• Geografické názvy
• Antarktida MeSH
• Názvy látek
• fotosystém II (proteinový komplex) MeSH
• voda MeSH

Short-term heat exposure in tropical regions can generate severe stress in the photosynthetic activity of soil crust cyanobacteria. We investigated the responses of two filamentous cyanobacteria, Scytonema tolypothrichoides and Tolypothrix bouteillei, to 1hr exposure at 35, 45, and 55 °C using variable chlorophyll fluorescence. Protocols for maximum quantum yield (FV/FM) and dark recovery of chlorophyll a fluorescence (OJIP) transient were applied. Heat exposure caused damage to the donor side of PSII, indicated by a decrease in FV/FM and a rapid increase in F0. After heat stress, photochemical energy utilization (φPo, φETo, and φRE1o) declined and energy dissipation (φDIo) increased. At 45 °C, the photosynthetic apparatus was reversibly damaged, since full recovery was observed after 7 days of relaxation. S. tolypothrichoides was more resistant to heat stress than T. bouteillei, confirming better adaptation to higher temperatures as observed in growth experiments.

• Klíčová slova
• Cyanobacteria, Heat stress, OJIP transient, Photosynthesis,
• MeSH
• bakteriální proteiny metabolismus   MeSH
• časové faktory MeSH
• chlorofyl a metabolismus   MeSH
• fluorescence MeSH
• fotosyntetická reakční centra (proteinové komplexy) metabolismus   MeSH
• fotosyntéza fyziologie   MeSH
• kvantová teorie MeSH
• pravděpodobnost MeSH
• půdní mikrobiologie * MeSH
• reakce na tepelný šok * MeSH
• sinice fyziologie   MeSH
• transport elektronů MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• bakteriální proteiny MeSH
• chlorofyl a MeSH
• fotosyntetická reakční centra (proteinové komplexy) MeSH

Current knowledge of the genetic mechanisms underlying the inheritance of photosynthetic activity in forest trees is generally limited, yet it is essential both for various practical forestry purposes and for better understanding of broader evolutionary mechanisms. In this study, we investigated genetic variation underlying selected chlorophyll a fluorescence (ChlF) parameters in structured populations of Scots pine (Pinus sylvestris L.) grown on two sites under non-stress conditions. These parameters were derived from the OJIP part of the ChlF kinetics curve and characterize individual parts of primary photosynthetic processes associated, for example, with the exciton trapping by light-harvesting antennae, energy utilization in photosystem II (PSII) reaction centers (RCs) and its transfer further down the photosynthetic electron-transport chain. An additive relationship matrix was estimated based on pedigree reconstruction, utilizing a set of highly polymorphic single sequence repeat markers. Variance decomposition was conducted using the animal genetic evaluation mixed-linear model. The majority of ChlF parameters in the analyzed pine populations showed significant additive genetic variation. Statistically significant heritability estimates were obtained for most ChlF indices, with the exception of DI0/RC, φD0 and φP0 (Fv/Fm) parameters. Estimated heritabilities varied around the value of 0.15 with the maximal value of 0.23 in the ET0/RC parameter, which indicates electron-transport flux from QA to QB per PSII RC. No significant correlation was found between these indices and selected growth traits. Moreover, no genotype × environment interaction (G × E) was detected, i.e., no differences in genotypes' performance between sites. The absence of significant G × E in our study is interesting, given the relatively low heritability found for the majority of parameters analyzed. Therefore, we infer that polygenic variability of these indices is selectively neutral.

• Klíčová slova
• OJIP transient, pedigree reconstruction, photosynthesis,
• MeSH
• borovice lesní genetika   fyziologie   MeSH
• chlorofyl a MeSH
• chlorofyl fyziologie   MeSH
• fluorescence MeSH
• fotosyntetická reakční centra (proteinové komplexy) fyziologie   MeSH
• fotosyntéza genetika   MeSH
• fotosystém II (proteinový komplex) fyziologie   MeSH
• genetická variace * MeSH
• genotyp * MeSH
• kvantitativní znak dědičný * MeSH
• lesy MeSH
• rostlinné geny MeSH
• stromy genetika   fyziologie   MeSH
• světlo MeSH
• transport elektronů MeSH
• zvířata MeSH
• Check Tag
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• chlorofyl a MeSH
• chlorofyl MeSH
• fotosyntetická reakční centra (proteinové komplexy) MeSH
• fotosystém II (proteinový komplex) MeSH

This work reveals, by imaging in vivo measurements in the Cd/Zn hyperaccumulator Arabidopsis halleri, in how far Cd stress affects macronutrient (Ca, K) and micronutrient (Fe, Zn) distribution in the leaves. We directly correlate these changes with biophysics of the photosynthetic light reactions. Plants were grown for 2 months at 10 μM Zn (=control), and supplemented with 10, 15, 50 or 75 μM Cd. Direct imaging of OJIP transients revealed that bundle sheath cells were more sensitive to Cd toxicity than mesophyll cells further from the vein. Progressive inhibition of photosystem (PS) II reaction centres and decrease in quantum yield of electron transport between QA and QB and further to PSI acceptors was observed. This was correlated with the decreased dynamics of QA re-oxidation and lower operating efficiency of PSII. Analysis by a benchtop micro X-ray fluorescence device showed that Cd mostly accumulated in the veins, and restricted Fe and Zn distribution from the veins, especially in the 75 μM Cd, while K concentration increased in the whole leaf. Calcium distribution was apparently not affected by Cd, but Cd excess inhibited trichome formation and thereby diminished total Ca concentration in the leaves. The results point to differential tissue sensitivity to Cd, evident by heterogeneous inhibition of photosynthesis. Part of this may be a result of selective disturbances in the leaf nutrient homeostasis. The better photosynthetic performance away from the veins compared to the bundle sheath cells, however, indicates that direct inhibition of photosynthesis by Cd dominates over inhibition caused by micronutrient deficiency.

• Klíčová slova
• Arabidopsis halleri, Cadmium, Chlorophyll fluorescence kinetics, OJIP, Tissue-specific metal distribution, Zinc, μXRF,
• MeSH
• Arabidopsis účinky léků   fyziologie   MeSH
• chlorofyl MeSH
• fotosyntéza * MeSH
• fyziologický stres * MeSH
• kadmium toxicita   MeSH
• listy rostlin MeSH
• mikroživiny MeSH
• trichomy MeSH
• zinek metabolismus   MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• chlorofyl MeSH
• kadmium MeSH
• mikroživiny MeSH
• zinek MeSH

In the current study, we used four soybean varieties PK-1029, PK-472, NRC-7, and Hardee to examine the effect of exclusion of solar UV radiation on photosynthetic efficiency and to test possible variety-dependent sensitivity to ambient UV (280-400 nm). Plants that were grown under UV exclusion filters had higher chlorophyll a and b, efficiencies of PSII and more active reaction centers indicated that PSII were substantially affected by solar UV radiation. The significant increase in net photosynthesis was linked to increased stomatal conductance and lower intercellular concentration of CO2 in UV-excluded plants. The exclusion of solar UV increased seed mass per plant in all soybean varieties as compared to the control; this indicates that ambient UV exclusions boost photosynthetic efficiency and improve soybean yield. The overall cumulative stress response index of four varieties implies that Hardee and PK-472 were more sensitive whereas NRC-7 and PK-1029 were resistant to ambient UV radiations.

• Klíčová slova
• OJIP transient, PSII efficiency, UV exclusion, chlorophyll fluorescence, photosynthesis, soybean,
• Publikační typ
• časopisecké články MeSH

The aim of this study was to explore how the mitochondrial alternative oxidase (AOX) pathway alleviates photoinhibition in chilled tomato (Solanum lycopersicum) seedlings. Chilling induced photoinhibition in tomato seedlings despite the increases in thermal energy dissipation and cyclic electron flow around PSI (CEF-PSI). Chilling inhibited the function of PSII and blocked electron transport at the PSII acceptor side, however, it did not affect the oxygen-evolving complex on the donor side of PSII. Upregulation of the AOX pathway protects against photoinhibition by improving PSII function and photosynthetic electron transport in tomato seedlings under chilling stress. The AOX pathway maintained the open state of PSII and the stability of the entire photosynthetic electron transport chain. Moreover, the protective role of the AOX pathway on PSII was more important than that on PSI. However, inhibition of the AOX pathway could be compensated by increasing CEF-PSI activity under chilling stress.

• Klíčová slova
• JIP-test, OJIP curve, Solanum lycopersicum, chlorophyll fluorescence, salicylhydroxamic acid,
• Publikační typ
• časopisecké články MeSH