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Nature Reviews. Molecular Cell Biology May 2024
PubMed: 38589639
DOI: 10.1038/s41580-024-00732-0 -
The Journal of General and Applied... Feb 2024Although n-butanol (BuOH) is an ideal fuel because of its superior physical properties, it has toxicity to microbes. Previously, a Synechococcus elongatus PCC 7942...
Although n-butanol (BuOH) is an ideal fuel because of its superior physical properties, it has toxicity to microbes. Previously, a Synechococcus elongatus PCC 7942 derivative strain that produces BuOH from CO was developed by introducing six heterologous genes (BUOH-SE strain). To identify the bottleneck in BuOH production, the effects of BuOH production and its toxicity on central metabolism and the photosystem were investigated. Parental (WT) and BUOH-SE strains were cultured under autotrophic conditions. Consistent with the results of a previous study, BuOH production was observed only in the BUOH-SE strain. Isotopically non-stationary C-metabolic flux analysis revealed that the CO fixation rate was much larger than the BuOH production rate in the BUOH-SE strain (1.70 vs 0.03 mmol gDCW h), implying that the carbon flow for BuOH biosynthesis was less affected by the entire flux distribution. No large difference was observed in the flux of metabolism between the WT and BUOH-SE strains. Contrastingly, in the photosystem, the chlorophyll content and maximum O evolution rate per dry cell weight of the BUOH-SE strain were decreased to 81% and 43% of the WT strain, respectively. Target proteome analysis revealed that the amounts of some proteins related to antennae (ApcA, ApcD, ApcE, and CpcC), photosystem II (PsbB, PsbU, and Psb28-2), and cytochrome bf complex (PetB and PetC) in photosystems decreased in the BUOH-SE strain. The activation of photosynthesis would be a novel approach for further enhancing BuOH production in S. elongatus PCC 7942.
Topics: 1-Butanol; Proteome; Cytochrome b6f Complex; Carbon Dioxide; Photosynthesis; Butanols
PubMed: 36935115
DOI: 10.2323/jgam.2023.03.002 -
Biosensors Aug 2023Most agricultural land, as a result of climate change, experiences severe stress that significantly reduces agricultural yields. Crop sensing by imaging techniques... (Review)
Review
Most agricultural land, as a result of climate change, experiences severe stress that significantly reduces agricultural yields. Crop sensing by imaging techniques allows early-stage detection of biotic or abiotic stress to avoid damage and significant yield losses. Among the top certified imaging techniques for plant stress detection is chlorophyll fluorescence imaging, which can evaluate spatiotemporal leaf changes, permitting the pre-symptomatic monitoring of plant physiological status long before any visible symptoms develop, allowing for high-throughput assessment. Here, we review different examples of how chlorophyll fluorescence imaging analysis can be used to evaluate biotic and abiotic stress. Chlorophyll is able to detect biotic stress as early as 15 min after feeding, or 30 min after application on tomato plants, or on the onset of water-deficit stress, and thus has potential for early stress detection. Chlorophyll fluorescence (ChlF) analysis is a rapid, non-invasive, easy to perform, low-cost, and highly sensitive method that can estimate photosynthetic performance and detect the influence of diverse stresses on plants. In terms of ChlF parameters, the fraction of open photosystem II (PSII) reaction centers (q) can be used for early stress detection, since it has been found in many recent studies to be the most accurate and appropriate indicator for ChlF-based screening of the impact of environmental stress on plants.
Topics: Humans; Chlorophyll A; Agriculture; Dehydration; Optical Imaging; Stress, Physiological
PubMed: 37622882
DOI: 10.3390/bios13080796 -
Scientific Reports Jul 2023We have analyzed the effect of salinity on photosystem II (PSII) photochemistry and plastoquinone (PQ) pool in halophytic Mesembryanthemum crystallinum plants. Under...
We have analyzed the effect of salinity on photosystem II (PSII) photochemistry and plastoquinone (PQ) pool in halophytic Mesembryanthemum crystallinum plants. Under prolonged salinity conditions (7 or 10 days of 0.4 M NaCl treatment) we noted an enlarged pool of open PSII reaction centers and increased energy conservation efficiency, as envisaged by parameters of the fast and slow kinetics of chlorophyll a fluorescence. Measurements of oxygen evolution, using 2,6-dichloro-1,4-benzoquinone as an electron acceptor, showed stimulation of the PSII activity due to salinity. In salt-acclimated plants (10 days of NaCl treatment), the improved PSII performance was associated with an increase in the size of the photochemically active PQ pool and the extent of its reduction. This was accompanied by a rise in the NADP/NADPH ratio. The presented data suggest that a redistribution of PQ molecules between photochemically active and non-active fractions and a change of the redox state of the photochemically active PQ pool indicate and regulate the acclimation of the photosynthetic apparatus to salinity.
Topics: Plastoquinone; Salt-Tolerant Plants; Mesembryanthemum; Chlorophyll A; Salinity; Sodium Chloride; Oxidation-Reduction; NADP; Photosystem II Protein Complex
PubMed: 37430104
DOI: 10.1038/s41598-023-38194-7 -
Tree Physiology Jul 2023Zinc (Zn) is a widespread industrial pollutant that has detrimental effects on plant growth and development. Photoprotective properties ensure plant survival during...
Zinc (Zn) is a widespread industrial pollutant that has detrimental effects on plant growth and development. Photoprotective properties ensure plant survival during stress by protecting the photosynthetic apparatus. This occurs via numerous mechanisms, including non-photochemical quenching (NPQ), cyclic electron flow (CEF) and the water-to-water cycle (WWC). However, whether and how Zn stress affects the photoprotective properties of plants to enhance the tolerance of Zn toxicity remains unknown. In this study, we treated Melia azedarach plants with different Zn concentrations ranging from 200 to 1000 mg kg-1. We then analyzed the activities of two leaf photosynthetic pigment components-photosystems I and II (PSI and PSII)-and the relative expression levels of their subunit genes. As expected, we found that Zn treatment decreases photosynthesis and increases photodamage in M. azedarach leaves. The Zn treatments exacerbated a variety of photodamage phenotypes in photosystem activities and altered the expression levels of key photosystem complex genes and proteins. Furthermore, our results demonstrated that PSI was more seriously damaged than PSII under Zn stress. Subsequently, we compared differences in photodamage in the NPQ, CEF and WWC photoprotection pathways under Zn stress and found that each exerted a protective function again photodamage under 200 mg kg-1 Zn stress. The NPQ and CEF may also play major protective roles in the avoidance of irreversible photodamage and helping to ensure survival under higher (i.e., 500 and 1000 mg kg-1) levels of Zn stress. Thus, our study revealed that NPQ- and CEF-based photoprotection mechanisms are more effective than WWC in M. azedarach upon Zn stress.
Topics: Electron Transport; Chlorophyll; Melia azedarach; Zinc; Electrons; Water Cycle; Photosystem II Protein Complex; Photosynthesis; Photosystem I Protein Complex; Plant Leaves; Water; Light
PubMed: 37073465
DOI: 10.1093/treephys/tpad045 -
Scientific Reports Nov 2023Symbiodiniaceae form associations with extra- and intracellular bacterial symbionts, both in culture and in symbiosis with corals. Bacterial associates can regulate...
Symbiodiniaceae form associations with extra- and intracellular bacterial symbionts, both in culture and in symbiosis with corals. Bacterial associates can regulate Symbiodiniaceae fitness in terms of growth, calcification and photophysiology. However, the influence of these bacteria on interactive stressors, such as temperature and light, which are known to influence Symbiodiniaceae physiology, remains unclear. Here, we examined the photophysiological response of two Symbiodiniaceae species (Symbiodinium microadriaticum and Breviolum minutum) cultured under acute temperature and light stress with specific bacterial partners from their microbiome (Labrenzia (Roseibium) alexandrii, Marinobacter adhaerens or Muricauda aquimarina). Overall, bacterial presence positively impacted Symbiodiniaceae core photosynthetic health (photosystem II [PSII] quantum yield) and photoprotective capacity (non-photochemical quenching; NPQ) compared to cultures with all extracellular bacteria removed, although specific benefits were variable across Symbiodiniaceae genera and growth phase. Symbiodiniaceae co-cultured with M. aquimarina displayed an inverse NPQ response under high temperatures and light, and those with L. alexandrii demonstrated a lowered threshold for induction of NPQ, potentially through the provision of antioxidant compounds such as zeaxanthin (produced by Muricauda spp.) and dimethylsulfoniopropionate (DMSP; produced by this strain of L. alexandrii). Our co-culture approach empirically demonstrates the benefits bacteria can deliver to Symbiodiniaceae photochemical performance, providing evidence that bacterial associates can play important functional roles for Symbiodiniaceae.
Topics: Animals; Anthozoa; Photosynthesis; Temperature; Bacteria; Photosystem II Protein Complex; Dinoflagellida; Symbiosis
PubMed: 38007500
DOI: 10.1038/s41598-023-48020-9 -
Inorganic Chemistry Oct 2023Transition-metal chalcogenide quantum dots (TMCs QDs) exhibit emerging potential in the field of solar energy conversion due to large absorption coefficients for light...
Transition-metal chalcogenide quantum dots (TMCs QDs) exhibit emerging potential in the field of solar energy conversion due to large absorption coefficients for light harvesting, quantum size effect, and abundant active sites. However, fine-tuning the photoinduced charge carrier over TMCs QDs to manipulate the directional charge-transfer pathway remains challenging, considering their ultrashort charge lifetime and slow charge-transfer kinetics. To this end, herein, MoS/PDDA/TMCs QDs heterostructures were exquisitely designed by a simple and green electrostatic self-assembly strategy under ambient conditions, wherein tailor-made negatively charged TMCs QDs stabilized by mercaptoacetic acid (MAA) were precisely self-assembled on the positively charged polydiallyl dimethylammonium chloride (PDDA)-modified MoS nanoflowers (NFs), forming a well-defined three-dimensional heterostructured nanoarchitecture. As an electron trapping agent, an MoS NFs cocatalyst benefits the unidirectional electron transfer from TMCs QDs to the ideal active centers on the MoS NFs surface by tunneling the ultrathin insulating polymer interim layer, thereby boosting the charge separation efficiency and endowing self-assembled MoS/PDDA/TMCs QDs heterostructures with considerably increased photocatalytic hydrogen evolution activity (1.96 mmol·g·h) and admirable stability under visible light irradiation. Our work will provide new insights into smart regulation of directional charge transfer over TMCs QDs-based photosystems for solar energy conversion.
PubMed: 37827854
DOI: 10.1021/acs.inorgchem.3c02857 -
The Plant Cell Apr 2024Photosynthetic control (PCON) is a protective mechanism that prevents light-induced damage to photosystem I (PSI) by ensuring the rate of NADPH and ATP production via...
Photosynthetic control (PCON) is a protective mechanism that prevents light-induced damage to photosystem I (PSI) by ensuring the rate of NADPH and ATP production via linear electron transfer (LET) is balanced by their consumption in the CO2 fixation reactions. Protection of PSI is a priority for plants since they lack a dedicated rapid-repair cycle for this complex, meaning that any damage leads to prolonged photoinhibition and decreased growth. The imbalance between LET and the CO2 fixation reactions is sensed at the level of the transthylakoid ΔpH, which increases when light is in excess. The canonical mechanism of PCON involves feedback control by ΔpH on the plastoquinol oxidation step of LET at cytochrome b6f. PCON thereby maintains the PSI special pair chlorophylls (P700) in an oxidized state, that allows excess electrons unused in the CO2 fixation reactions to be safely quenched via charge recombination. In this review we focus on angiosperms, considering how photo-oxidative damage to PSI comes about, explore the consequences of PSI photoinhibition on photosynthesis and growth, discuss recent progress in understanding PCON regulation, and finally consider the prospects for its future manipulation in crop plants to improve photosynthetic efficiency.
PubMed: 38668079
DOI: 10.1093/plcell/koae133 -
Doklady Biological Sciences :... Aug 2023The endogenous brassinosteroid (BS) profile was for the first time shown to change in response to salt stress in potato plants. A group of 6-keto-BSs was identified and...
The endogenous brassinosteroid (BS) profile was for the first time shown to change in response to salt stress in potato plants. A group of 6-keto-BSs was identified and found to significantly increase in content during salinization in contrast to other groups of hormones examined. A tenfold reduction in the level of endogenous BSs in mutant Arabidopsis thaliana plants with impaired biosynthesis (det2) (or reception (bri1)) of phytosteroids decreased their salt resistance, as evidenced by a lower efficiency of photochemical processes of photosystem II (PSII) and growth inhibition. The results confirmed the idea that endogenous BSs are involved in the formation of salt resistance in plants.
Topics: Brassinosteroids; Arabidopsis; Arabidopsis Proteins
PubMed: 37833583
DOI: 10.1134/S0012496623700485 -
Nature Communications Dec 2023Diatoms are dominant marine algae and contribute around a quarter of global primary productivity, the success of which is largely attributed to their photosynthetic...
Diatoms are dominant marine algae and contribute around a quarter of global primary productivity, the success of which is largely attributed to their photosynthetic capacity aided by specific fucoxanthin chlorophyll-binding proteins (FCPs) to enhance the blue-green light absorption under water. We purified a photosystem II (PSII)-FCPII supercomplex and a trimeric FCP from Cyclotella meneghiniana (Cm) and solved their structures by cryo-electron microscopy (cryo-EM). The structures reveal detailed organizations of monomeric, dimeric and trimeric FCP antennae, as well as distinct assemblies of Lhcx6_1 and dimeric FCPII-H in PSII core. Each Cm-PSII-FCPII monomer contains an Lhcx6_1, an FCP heterodimer and other three FCP monomers, which form an efficient pigment network for harvesting energy. More diadinoxanthins and diatoxanthins are found in FCPs, which may function to quench excess energy. The trimeric FCP contains more chlorophylls c and fucoxanthins. These diversified FCPs and PSII-FCPII provide a structural basis for efficient light energy harvesting, transfer, and dissipation in C. meneghiniana.
Topics: Photosystem II Protein Complex; Diatoms; Cryoelectron Microscopy; Chlorophyll Binding Proteins; Photosynthesis; Light-Harvesting Protein Complexes
PubMed: 38071196
DOI: 10.1038/s41467-023-44055-8