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Journal of Agricultural and Food... May 2024For healthier human nutrition, it is desirable to provide food with a high content of nutraceuticals such as polyphenolics, vitamins, and carotenoids. We investigated to...
For healthier human nutrition, it is desirable to provide food with a high content of nutraceuticals such as polyphenolics, vitamins, and carotenoids. We investigated to what extent high growth irradiance influences the content of phenolics, α-tocopherol and carotenoids, in wild rocket (), which is increasingly used as a salad green. Potted plants were grown in a climate chamber with a 16 h day length at photosynthetic photon flux densities varying from 20 to 1250 μmol m s. Measurements of the maximal quantum yield of photosystem II, F/F, and of the epoxidation state of the violaxanthin cycle (V-cycle) showed that the plants did not suffer from excessive light for photosynthesis. Contents of carotenoids belonging to the V-cycle, α-tocopherol and several quercetin derivatives, increased nearly linearly with irradiance. Nonintrusive measurements of chlorophyll fluorescence induced by UV-A and blue light relative to that induced by red light, indicating flavonoid and carotenoid content, allowed not only a semiquantitative measurement of both compounds but also allowed to follow their dynamic changes during reciprocal transfers between low and high growth irradiance. The results show that growth irradiance has a strong influence on the content of three different types of compounds with antioxidative properties and that it is possible to determine the contents of flavonoids and specific carotenoids in intact leaves using chlorophyll fluorescence. The results may be used for breeding to enhance healthy compounds in wild rocket leaves and to monitor their content for selection of appropriate genotypes.
Topics: Carotenoids; Chlorophyll; Light; Photosynthesis; alpha-Tocopherol; Antioxidants; Phenols; Flavonoids; Plant Leaves
PubMed: 38648561
DOI: 10.1021/acs.jafc.3c07698 -
Bioresources and Bioprocessing Jul 2023Solar radiation varies quantitatively and qualitatively while penetrating through the seawater column and thus is one of the most important environmental factors shaping...
Solar radiation varies quantitatively and qualitatively while penetrating through the seawater column and thus is one of the most important environmental factors shaping the vertical distribution pattern of phytoplankton. The haploid and diploid life-cycle phases of coccolithophores might have different vertical distribution preferences. Therefore, the two phases respond differently to high solar photosynthetically active radiation (PAR, 400-700 nm) and ultraviolet radiation (UVR, 280-400 nm). To test this, the haploid and diploid Emiliania huxleyi were exposed to oversaturating irradiance. In the presence of PAR alone, the effective quantum yield was reduced by 10% more due to the higher damage rate of photosystem II in haploid cells than in diploid cells. The addition of UVR resulted in further inhibition of the quantum yield for both haploid and diploid cells in the first 25 min, partly because of the increased damage of photosystem II. Intriguingly, this UVR-induced inhibition of the haploid cells completely recovered half an hour later. This recovery was confirmed by the comparable maximum quantum yields, maximum relative electron transport rates and yields of the haploid cells treated with PAR and PAR + UVR. Our data indicated that photosynthesis of the haploid phase was more sensitive to high visible light than the diploid phase but resistant to UVR-induced inhibition, reflecting the ecological niches to which this species adapts.
PubMed: 38647570
DOI: 10.1186/s40643-023-00660-5 -
Advanced Science (Weinheim,... Jun 2024Natural photosynthesis holds great potential to generate clean electricity from solar energy. In order to utilize this process for power generation, it is necessary to...
Natural photosynthesis holds great potential to generate clean electricity from solar energy. In order to utilize this process for power generation, it is necessary to rewire photosynthetic electron transport chains (PETCs) of living photosynthetic organisms to redirect more electron flux toward an extracellular electrode. In this study, a semi-artificial rewiring strategy, which use a water-soluble fullerene derivative to capture electrons from PETCs and donate them for electrical current generation, is proposed. A positively charged fullerene derivative, functionalized with N,N-dimethyl pyrrolidinium iodide, is found to be efficiently taken up by the cyanobacterium Synechocystis sp. PCC 6803. The distribution of this fullerene derivative near the thylakoid membrane, as well as site-specific inhibitor assays and transient absorption spectroscopy, suggest that it can directly interact with the redox centers in the PETCs, particularly the acceptor side of photosystem I (PSI). The internalized fullerene derivatives facilitate the extraction of photosynthetic electrons and significantly enhance the photocurrent density of Synechocystis by approximately tenfold. This work opens up new possibility for the application of fullerenes as an excellent 3D electron carrier in living biophotovoltaics.
Topics: Fullerenes; Photosynthesis; Solar Energy; Synechocystis; Water; Electron Transport; Electricity
PubMed: 38647389
DOI: 10.1002/advs.202310245 -
Nature Communications Apr 2024Dinoflagellates are ecologically important and essential to corals and other cnidarians as phytosymbionts, but their photosystems had been underexplored. Recently,...
Dinoflagellates are ecologically important and essential to corals and other cnidarians as phytosymbionts, but their photosystems had been underexplored. Recently, photosystem I (PSI) of dinoflagellate sp. was structurally characterized using cryo-Electron Microscopy (cryo-EM). These analyses revealed a distinct organization of the PSI supercomplex, including two previously unidentified subunits, PsaT and PsaU, and shed light on interactions between light harvesting antenna proteins and the PSI core. These results have implications with respect to the evolution of dinoflagellates and their association with cnidarians.
Topics: Photosystem I Protein Complex; Photosynthesis; Chlorophyll; Dinoflagellida; Photosystem II Protein Complex; Light; Light-Harvesting Protein Complexes
PubMed: 38637576
DOI: 10.1038/s41467-024-47797-1 -
Nature Communications Apr 2024The discovery of Mn-Ca complex in photosystem II stimulates research of manganese-based catalysts for oxygen evolution reaction (OER). However, conventional chemical...
The discovery of Mn-Ca complex in photosystem II stimulates research of manganese-based catalysts for oxygen evolution reaction (OER). However, conventional chemical strategies face challenges in regulating the four electron-proton processes of OER. Herein, we investigate alpha-manganese dioxide (α-MnO) with typical Mn-O-Mn-HO motifs as a model for adjusting proton coupling. We reveal that pre-equilibrium proton-coupled redox transition provides an adjustable energy profile for OER, paving the way for in-situ enhancing proton coupling through a new "reagent"- external electric field. Based on the α-MnO single-nanowire device, gate voltage induces a 4-fold increase in OER current density at 1.7 V versus reversible hydrogen electrode. Moreover, the proof-of-principle external electric field-assisted flow cell for water splitting demonstrates a 34% increase in current density and a 44.7 mW/cm² increase in net output power. These findings indicate an in-depth understanding of the role of proton-incorporated redox transition and develop practical approach for high-efficiency electrocatalysis.
PubMed: 38637529
DOI: 10.1038/s41467-024-47568-y -
PloS One 2024Drought stress (DS) is one of the important abiotic stresses facing cash crops today. Drought can reduce plant growth and development, inhibit photosynthesis, and thus...
Drought stress (DS) is one of the important abiotic stresses facing cash crops today. Drought can reduce plant growth and development, inhibit photosynthesis, and thus reduce plant yield. In this experiment, we investigated the protective mechanism of AMF on plant photosynthetic system by inoculating Paris polyphylla var. yunnanensis(P.py) with a clumping mycorrhizal fungus (AMF) under drought conditions. The drought environment was maintained by weighing AMF plants and non-AMF plants. The relative water content (RWC) of plant leaves was measured to determine its drought effect. DS decreased the RWC of plants, but AMF was able to increase the RWC of plants. chlorophyll a fluorescence curve measurements revealed that DS increased the OKJIP curve of plants, but AMF was able to reduce this trend, indicating that AMF increased the light absorption capacity of plants. DS also caused a decrease in plant Y(I) and Y(II). ETRI and ETRII, and increased Y(NO) and Y(NA) in plants, indicating that DS caused photosystem damage in plants. For the same host, different AMFs did not help to the same extent, but all AMFs were able to help plants reduce this damage and contribute to the increase of plant photosynthesis under normal water conditions.
Topics: Mycorrhizae; Chlorophyll A; Droughts; Water; Liliaceae
PubMed: 38635811
DOI: 10.1371/journal.pone.0294394 -
Biotechnologia 2024The microRNAs are endogenous, regulating gene expression either at the DNA or RNA level. Despite the availability of extensive studies on microRNA generation in plants,...
The microRNAs are endogenous, regulating gene expression either at the DNA or RNA level. Despite the availability of extensive studies on microRNA generation in plants, reports on their abundance, biogenesis, and consequent gene regulation in plant organelles remain naVve. Building on previous studies involving pre-miRNA sequencing in , we demonstrated that three putative microRNAs were raised from the chloroplast genome. In the current study, we have characterized the genesis of these three microRNAs through a combination of bioinformatics and experimental approaches. The gene sequence for a miRNA, designated as AecpmiRNA1 ( chloroplast miRNA), is potentially located in both the genomic DNA, i.e., nuclear and chloroplast genome. In contrast, the gene sequences for the other two miRNAs (AecpmiRNA2 and AecpmiRNA3) are exclusively present in the chloroplast genome. Target prediction revealed many potential mRNAs as targets for AecpmiRNAs. Further analysis using 5' RACE-PCR determined the AecpmiRNA3 binding and cleavage site at the photosystem II protein N (psbN). These results indicate that AecpmiRNAs are generated from the chloroplast genome, possessing the potential to regulate mRNAs arising from chloroplast gene(s). On the other side, the possibility of nuclear genome-derived mRNA regulation by AecpmiRNAs cannot be ruled out.
PubMed: 38633894
DOI: 10.5114/bta.2024.135639 -
BMC Plant Biology Apr 2024Several plants are facing drought stress due to climate change in recent years. In this study, we aimed to explore the effect of varying watering frequency on the growth...
BACKGROUND
Several plants are facing drought stress due to climate change in recent years. In this study, we aimed to explore the effect of varying watering frequency on the growth and photosynthetic characteristics of Hosta 'Guacamole'. Moreover, we investigated the effect of high-nitrogen and -potassium fertilizers on alleviating the impacts of drought stress on the morphology, photosynthetic characteristics, chlorophyll fluorescence, fast chlorophyll a fluorescence transient, JIP-test parameters, and enzymatic and non-enzymatic scavenging system for reactive oxygen species (ROS) in this species.
RESULTS
Leaf senescence, decreased chlorophyll contents, limited leaf area, and reduced photosynthetic characteristics and oxygen-evolving complex (OEC) activity were observed in Hosta 'Guacamole' under drought stress. However, high-nitrogen fertilizer (30-10-10) could efficiently alleviate and prevent the adverse effects of drought stress. High-nitrogen fertilizer significantly increased chlorophyll contents, which was higher by 106% than drought stress. Additionally, high-nitrogen fertilizer significantly improved net photosynthetic rate and water use efficiency, which were higher by 467% and 2900% than those under drought stress. It attributes that high-nitrogen fertilizer could reduce transpiration rate of leaf cells and stomatal opening size in drought stress. On the other hand, high-nitrogen fertilizer enhanced actual photochemical efficiency of PS II and photochemical quenching coefficient, and actual photochemical efficiency of PS II significantly higher by 177% than that under drought stress. Furthermore, high-nitrogen fertilizer significantly activated OEC and ascorbate peroxidase activities, and enhanced the performance of photosystem II and photosynthetic capacity compared with high-potassium fertilizers (15-10-30).
CONCLUSIONS
High-nitrogen fertilizer (30-10-10) could efficiently alleviate the adverse effects of drought stress in Hosta 'Guacamole' via enhancing OEC activity and photosynthetic performance and stimulating enzymatic ROS scavenging system.
Topics: Fertilizers; Nitrogen; Hosta; Chlorophyll A; Droughts; Reactive Oxygen Species; Photosynthesis; Chlorophyll; Photosystem II Protein Complex; Potassium; Plant Leaves
PubMed: 38632552
DOI: 10.1186/s12870-024-04929-5 -
International Journal of Molecular... Apr 2024We establish a general kinetic scheme for the energy transfer and radical-pair dynamics in photosystem I (PSI) of , PCC6803, and grown under white-light conditions....
We establish a general kinetic scheme for the energy transfer and radical-pair dynamics in photosystem I (PSI) of , PCC6803, and grown under white-light conditions. With the help of simultaneous target analysis of transient-absorption data sets measured with two selective excitations, we resolved the spectral and kinetic properties of the different species present in PSI. WL-PSI can be described as a Bulk Chl in equilibrium with a higher-energy Chl one or two Red Chl and a reaction-center compartment (WL-RC). Three radical pairs (RPs) have been resolved with very similar properties in the four model organisms. The charge separation is virtually irreversible with a rate of ≈900 ns. The second rate, of RP1 → RP2, ranges from 70-90 ns and the third rate, of RP2 → RP3, is ≈30 ns. Since RP1 and the Red Chl are simultaneously present, resolving the RP1 properties is challenging. In , the excited WL-RC and Bulk Chl compartments equilibrate with a lifetime of ≈0.28 ps, whereas the Red and the Bulk Chl compartments equilibrate with a lifetime of ≈2.65 ps. We present a description of the thermodynamic properties of the model organisms at room temperature.
Topics: Chlorophyll A; Photosystem I Protein Complex; Energy Transfer; Chlamydomonas reinhardtii; Kinetics
PubMed: 38612934
DOI: 10.3390/ijms25074125 -
International Journal of Molecular... Mar 2024Photosystem I (PSI) is one of the two main pigment-protein complexes where the primary steps of oxygenic photosynthesis take place. This review describes low-temperature... (Review)
Review
Photosystem I (PSI) is one of the two main pigment-protein complexes where the primary steps of oxygenic photosynthesis take place. This review describes low-temperature frequency-domain experiments (absorption, emission, circular dichroism, resonant and non-resonant hole-burned spectra) and modeling efforts reported for PSI in recent years. In particular, we focus on the spectral hole-burning studies, which are not as common in photosynthesis research as the time-domain spectroscopies. Experimental and modeling data obtained for trimeric cyanobacterial Photosystem I (PSI), PSI mutants, and PSI-IsiA supercomplexes are analyzed to provide a more comprehensive understanding of their excitonic structure and excitation energy transfer (EET) processes. Detailed information on the excitonic structure of photosynthetic complexes is essential to determine the structure-function relationship. We will focus on the so-called "red antenna states" of cyanobacterial PSI, as these states play an important role in photochemical processes and EET pathways. The high-resolution data and modeling studies presented here provide additional information on the energetics of the lowest energy states and their chlorophyll (Chl) compositions, as well as the EET pathways and how they are altered by mutations. We present evidence that the low-energy traps observed in PSI are excitonically coupled states with significant charge-transfer (CT) character. The analysis presented for various optical spectra of PSI and PSI-IsiA supercomplexes allowed us to make inferences about EET from the IsiA ring to the PSI core and demonstrate that the number of entry points varies between sample preparations studied by different groups. In our most recent samples, there most likely are three entry points for EET from the IsiA ring per the PSI core monomer, with two of these entry points likely being located next to each other. Therefore, there are nine entry points from the IsiA ring to the PSI trimer. We anticipate that the data discussed below will stimulate further research in this area, providing even more insight into the structure-based models of these important cyanobacterial photosystems.
Topics: Photosystem I Protein Complex; Circular Dichroism; Energy Transfer; Chlorophyll; Cold Temperature
PubMed: 38612659
DOI: 10.3390/ijms25073850