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Plants (Basel, Switzerland) May 2024The growing issue of salinity is a significant threat to global agriculture, affecting diverse regions worldwide. Nitric oxide (NO) serves as an essential signal...
The growing issue of salinity is a significant threat to global agriculture, affecting diverse regions worldwide. Nitric oxide (NO) serves as an essential signal molecule in regulating photosynthetic performance under physiological and stress conditions. The present study reveals the protective effects of different concentrations (0-300 µM) of sodium nitroprusside (SNP, a donor of NO) on the functions of the main complexes within the photosynthetic apparatus of maize ( L. Kerala) under salt stress (150 mM NaCl). The data showed that SNP alleviates salt-induced oxidative stress and prevents changes in the fluidity of thylakoid membranes (Laurdan GP) and energy redistribution between the two photosystems (77K chlorophyll fluorescence ratio F/F). Chlorophyll fluorescence measurements demonstrated that the foliar spray with SNP under salt stress prevents the decline of photosystem II (PSII) open reaction centers (qP) and improves their efficiency (Φexc), thereby influencing Q reoxidation. The data also revealed that SNP protects the rate constants for two pathways of Q reoxidation (k and k) from the changes caused by NaCl treatment alone. Additionally, there is a predominance of Q interaction with plastoquinone in comparison to the recombination of electrons in Q Q with the oxygen-evolving complex (OEC). The analysis of flash oxygen evolution showed that SNP treatment prevents a salt-induced 10% increase in PSII centers in the S state, i.e., protects the initial S-S state distribution, and the modification of the Mn cluster in the OEC. Moreover, this study demonstrates that SNP-induced defense occurs on both the donor and acceptor sides of the PSII, leading to the protection of overall photosystems performance (PI) and efficient electron transfer from the PSII donor side to the reduction of PSI end electron acceptors (PItotal). This study clearly shows that the optimal protection under salt stress occurs at approximately 50-63 nmoles NO/g FW in leaves, corresponding to foliar spray with 50-150 µM SNP.
PubMed: 38794383
DOI: 10.3390/plants13101312 -
International Journal of Molecular... May 2024ROS-dependent induction of oxidative damage can be used as a trigger initiating genetically determined non-specific protection in plant cells and tissues. Plants are...
ROS-dependent induction of oxidative damage can be used as a trigger initiating genetically determined non-specific protection in plant cells and tissues. Plants are potentially able to withstand various specific (toxic, osmotic) factors of abiotic effects, but do not have sufficient or specific sensitivity to form an adequate effective response. In this work, we demonstrate one of the possible approaches for successful cold acclimation through the formation of effective protection of photosynthetic structures due to the insertion of the heterologous gene into the tobacco genome under the control of the constitutive promoter and equipped with a signal sequence targeting the protein to plastid. The increased enzymatic activity of superoxide dismutase in the plastid compartment of transgenic tobacco plants enables them to tolerate the oxidative factor of environmental stresses scavenging ROS. On the other hand, the cost of such resistance is quite high and, when grown under normal conditions, disturbs the arrangement of the intrachloroplastic subdomains leading to the modification of stromal thylakoids, probably significantly affecting the photosynthesis processes that regulate the efficiency of photosystem II. This is partially compensated for by the fact that, at the same time, under normal conditions, the production of peroxide induces the activation of ROS detoxification enzymes. However, a violation of a number of processes, such as the metabolism of accumulation, and utilization and transportation of sugars and starch, is significantly altered, which leads to a shift in metabolic chains. The expected step for further improvement of the applied technology could be both the use of inducible promoters in the expression cassette, and the addition of other genes encoding for hydrogen peroxide-scavenging enzymes in the genetic construct that are downstream in the metabolic chain.
Topics: Nicotiana; Oxidative Stress; Plastids; Superoxide Dismutase; Plants, Genetically Modified; Reactive Oxygen Species; Cold Temperature; Photosynthesis; Plant Proteins
PubMed: 38791585
DOI: 10.3390/ijms25105544 -
International Journal of Molecular... May 2024With the depletion of the ozone layer, the intensity of ultraviolet B (UV-B) radiation reaching the Earth's surface increases, which in turn causes significant stress to...
With the depletion of the ozone layer, the intensity of ultraviolet B (UV-B) radiation reaching the Earth's surface increases, which in turn causes significant stress to plants and affects all aspects of plant growth and development. The aim of this study was to investigate the mechanism of response to UV-B radiation in the endemic species of Pall. () in the Changbai Mountains and to study how exogenous ABA regulates the response of to UV-B stress. The results of chlorophyll fluorescence images and OJIP kinetic curves showed that UV-B radiation damaged the PSII photosystem of , and exogenous ABA could alleviate this damage to some extent. A total of 2148 metabolites were detected by metabolomics, of which flavonoids accounted for the highest number (487, or 22.67%). KEGG enrichment analysis of flavonoids that showed differential accumulation by UV-B radiation and exogenous ABA revealed that flavonoid biosynthesis and flavone and flavonol biosynthesis were significantly altered. GO analysis showed that most of the DEGs produced after UV-B radiation and exogenous ABA were distributed in the cellular process, cellular anatomical entity, and catalytic activity. Network analysis of key DFs and DEGs associated with flavonoid synthesis identified key flavonoids (isorhamnetin-3-O-gallate and dihydromyricetin) and genes (TRINITY_DN2213_c0_g1_i4-A1) that promote the resistance of to UV-B stress. In addition, multiple transcription factor families were found to be involved in the regulation of the flavonoid synthesis pathway under UV-B stress. Overall, actively responded to UV-B stress by regulating changes in flavonoids, especially flavones and flavonols, while exogenous ABA further enhanced its resistance to UV-B stress. The experimental results not only provide a new perspective for understanding the molecular mechanism of the response to UV-B stress in the , but also provide a valuable theoretical basis for future research and application in improving plant adversity tolerance.
Topics: Ultraviolet Rays; Abscisic Acid; Flavonoids; Rhododendron; Gene Expression Regulation, Plant; Chlorophyll
PubMed: 38791294
DOI: 10.3390/ijms25105248 -
International Journal of Molecular... May 2024Photosynthesis, as the primary source of energy for all life forms, plays a crucial role in maintaining the global balance of energy, entropy, and enthalpy in living... (Review)
Review
Photosynthesis, as the primary source of energy for all life forms, plays a crucial role in maintaining the global balance of energy, entropy, and enthalpy in living organisms. Among its various building blocks, photosystem I (PSI) is responsible for light-driven electron transfer, crucial for generating cellular reducing power. PSI acts as a light-driven plastocyanin-ferredoxin oxidoreductase and is situated in the thylakoid membranes of cyanobacteria and the chloroplasts of eukaryotic photosynthetic organisms. Comprehending the structure and function of the photosynthetic machinery is essential for understanding its mode of action. New insights are offered into the structure and function of PSI and its associated light-harvesting proteins, with a specific focus on the remarkable structural conservation of the core complex and high plasticity of the peripheral light-harvesting complexes.
Topics: Photosystem I Protein Complex; Photosynthesis; Light-Harvesting Protein Complexes; Cyanobacteria; Models, Molecular; Electron Transport
PubMed: 38791114
DOI: 10.3390/ijms25105073 -
International Journal of Molecular... May 2024Defoliation is an inevitable abiotic stress for forage and turf grasses because harvesting, grazing, and mowing are general processes for their production and...
Defoliation is an inevitable abiotic stress for forage and turf grasses because harvesting, grazing, and mowing are general processes for their production and management. Vegetative regrowth occurs upon defoliation, a crucial trait determining the productivity and persistence of these grasses. However, the information about the molecular regulation of this trait is limited because it is still challenging to perform molecular analyses in forage and turf grasses. Here, we used rice as a model to investigate vegetative regrowth upon defoliation at physiological and molecular levels. This study analyzed stubble and regrown leaves following periodic defoliation using two rice varieties with contrasting regrowth vigor. Vigorous regrowth was associated with maintained chlorophyll content and photosystem II performance; a restricted and promoted mRNA accumulation of sucrose synthase (SUS) I and III subfamilies, respectively; and reduced enzymatic activity of SUS. These results suggest that critical factors affecting vegetative regrowth upon defoliation are de novo carbohydrate synthesis by newly emerged leaves and proper carbohydrate management in leaves and stubble. Physiological and genetic analyses have demonstrated that the reduced sensitivity to and inhibited biosynthesis of cytokinin enhance regrowth vigor. Proper regulation of these metabolic and hormonal pathways identified in this study can lead to the development of new grass varieties with enhanced regrowth vigor following defoliation.
Topics: Oryza; Plant Leaves; Cytokinins; Gene Expression Regulation, Plant; Carbohydrate Metabolism; Plant Proteins; Glucosyltransferases; Chlorophyll; Photosystem II Protein Complex
PubMed: 38791109
DOI: 10.3390/ijms25105070 -
BMC Plant Biology May 2024Drosera intermedia grows in acidic bogs in parts of valleys that are flooded in winter, and that often dry out in summer. It is also described as the sundew of the most...
Drosera intermedia grows in acidic bogs in parts of valleys that are flooded in winter, and that often dry out in summer. It is also described as the sundew of the most heavily hydrated habitats in peatlands, and it is often found in water and even underwater. This sundew is the only one that can tolerate long periods of submersion, and more importantly produces a typical submerged form that can live in such conditions for many years. Submerged habitats are occupied by D. intermedia relatively frequently. The aim of the study was to determine the environmental conditions and architecture of individuals in the submerged form of D. intermedia. The features of the morphological and anatomical structure and chlorophyll a fluorescence of this form that were measured were compared with analogous ones in individuals that occurred in emerged and peatland habitats. The submerged form occurred to a depth of 20 cm. Compared to the other forms, its habitat had the highest pH (4.71-4.92; Me = 4.71), the highest temperature and substrate hydration, and above all, the lowest photosynthetically active radiation (PAR; 20.4-59.4%). This form differed from the other forms in almost all of the features of the plant's architecture. It is particularly noteworthy that it had the largest main axis height among all of the forms, which exceeded 18 cm. The number of living leaves in a rosette was notable (18.1 ± 8.1), while the number of dead leaves was very low (6.9 ± 3.8). The most significant differences were in the shape of its submerged leaves, in which the length of the leaf blade was the lowest of all of the forms (0.493 ± 0.15 mm; p < 0.001) and usually the widest. The stem cross-sectional area was noticeably smaller in the submerged form than in the other forms, the xylem was less developed and collaterally closed vascular bundles occurred. Our analysis of the parameters of chlorophyll fluorescence in vivo revealed that the maximum quantum yield of the primary photochemistry of photosystem II is the highest for the submerged form (Me = 0.681), the same as the maximum quantum yield of the electron transport (Me φE = 0.183). The efficiency of energy use per one active reaction center of photosystem II (RC) was the lowest in the submerged form (Me = 2.978), same as the fraction of energy trapped by one active RC (Me = 1.976) and the non-photochemical energy dissipation (DI/RC; Me = 0.916). The ET/RC parameter, associated with the efficiency of the energy utilization for electron transport by one RC, in the submerged plant reached the highest value (Me = 0.489). The submerged form of D. intermedia clearly differed from the emerged and peatland forms in its plant architecture. The submerged plants had a thinner leaf blade and less developed xylem than the other forms, however, their stems were much longer. The relatively high photosynthetic efficiency of the submerged forms suggests that most of the trapped energy is utilized to drive photosynthesis with a minimum energy loss, which may be a mechanism to compensate for the relatively small size of the leaf blade.
Topics: Photosynthesis; Chlorophyll; Plant Leaves; Ecosystem; Chlorophyll A; Temperature; Hydrogen-Ion Concentration; Water
PubMed: 38783181
DOI: 10.1186/s12870-024-05155-9 -
BMC Plant Biology May 2024Acacia nilotica Linn. is a widely distributed tree known for its applications in post-harvest and medicinal horticulture. However, its seed-based growth is relatively...
BACKGROUND
Acacia nilotica Linn. is a widely distributed tree known for its applications in post-harvest and medicinal horticulture. However, its seed-based growth is relatively slow. Seed is a vital component for the propagation of A. nilotica due to its cost-effectiveness, genetic diversity, and ease of handling. Colchicine, commonly used for polyploidy induction in plants, may act as a pollutant at elevated levels. Its optimal concentration for Acacia nilotica's improved growth and development has not yet been determined, and the precise mechanism underlying this phenomenon has not been established. Therefore, this study investigated the impact of optimized colchicine (0.07%) seed treatment on A. nilotica's morphological, anatomical, physiological, fluorescent, and biochemical attributes under controlled conditions, comparing it with a control.
RESULTS
Colchicine seed treatment significantly improved various plant attributes compared to control. This included increased shoot length (84.6%), root length (53.5%), shoot fresh weight (59.1%), root fresh weight (42.8%), shoot dry weight (51.5%), root dry weight (40%), fresh biomass (23.6%), stomatal size (35.9%), stomatal density (41.7%), stomatal index (51.2%), leaf thickness (11 times), leaf angle (2.4 times), photosynthetic rate (40%), water use efficiency (2.2 times), substomatal CO (36.6%), quantum yield of photosystem II (13.1%), proton flux (3.1 times), proton conductivity (2.3 times), linear electron flow (46.7%), enzymatic activities of catalase (25%), superoxide dismutase (33%), peroxidase (13.5%), and ascorbate peroxidase (28%), 2,2-diphenyl-1-picrylhydrazyl-radical scavenging activities(23%), total antioxidant capacity (59%), total phenolic (23%), and flavonoid content (37%) with less number of days to 80% germination (57.1%), transpiration rate (53.9%), stomatal conductance (67.1%), non-photochemical quenching (82.8%), non-regulatory energy dissipation (24.3%), and HO (25%) and O levels (30%).
CONCLUSION
These findings elucidate the intricate mechanism behind the morphological, anatomical, physiological, fluorescent, and biochemical transformative effects of colchicine seed treatment on Acacia nilotica Linn. and offer valuable insights for quick production of A. nilotica's plants with modification and enhancement from seeds through an eco-friendly approach.
Topics: Colchicine; Acacia; Seeds; Photosynthesis; Antioxidants
PubMed: 38773358
DOI: 10.1186/s12870-024-05139-9 -
International Journal of Biological... Jun 2024Proteases, essential regulators of plant stress responses, remain enigmatic in their precise functional roles. By employing activity-based probes for real-time...
Proteases, essential regulators of plant stress responses, remain enigmatic in their precise functional roles. By employing activity-based probes for real-time monitoring, this study aimed to delve into protease activities in Chlamydomonas reinhardtii exposed to oxidative stress induced by hydrogen peroxide. However, our work revealed that the activity-based probes strongly labelled three non-proteolytic proteins-PsbO, PsbP, and PsbQ-integral components of photosystem II's oxygen-evolving complex. Subsequent biochemical assays and mass spectrometry experiments revealed the involvement of CrCEP1, a previously uncharacterized papain-like cysteine protease, as the catalyst of this labelling reaction. Further experiments with recombinant CrCEP1 and PsbO proteins replicated the reaction in vitro. Our data unveiled that endopeptidase CrCEP1 also has transpeptidase activity, ligating probes and peptides to the N-termini of Psb proteins, thereby expanding the repertoire of its enzymatic activities. The hitherto unknown transpeptidase activity of CrCEP1, working in conjunction with its proteolytic activity, unveils putative complex and versatile roles for proteases in cellular processes during stress responses.
Topics: Cysteine Proteases; Chlamydomonas reinhardtii; Oxidative Stress; Photosystem II Protein Complex; Plant Proteins; Hydrogen Peroxide; Cysteine Endopeptidases
PubMed: 38768911
DOI: 10.1016/j.ijbiomac.2024.132505 -
Journal of the American Chemical Society May 2024The ability to harvest light effectively in a changing environment is necessary to ensure efficient photosynthesis and crop growth. One mechanism, known as qE, protects...
The ability to harvest light effectively in a changing environment is necessary to ensure efficient photosynthesis and crop growth. One mechanism, known as qE, protects photosystem II (PSII) and regulates electron transfer through the harmless dissipation of excess absorbed photons as heat. This process involves reversible clustering of the major light-harvesting complexes of PSII (LHCII) in the thylakoid membrane and relies upon the ΔpH gradient and the allosteric modulator protein PsbS. To date, the exact role of PsbS in the qE mechanism has remained elusive. Here, we show that PsbS induces hydrophobic mismatch in the thylakoid membrane through dynamic rearrangement of lipids around LHCII leading to observed membrane thinning. We found that upon illumination, the thylakoid membrane reversibly shrinks from around 4.3 to 3.2 nm, without PsbS, this response is eliminated. Furthermore, we show that the lipid digalactosyldiacylglycerol (DGDG) is repelled from the LHCII-PsbS complex due to an increase in both the p of lumenal residues and in the dipole moment of LHCII, which allows for further conformational change and clustering in the membrane. Our results suggest a mechanistic role for PsbS as a facilitator of a hydrophobic mismatch-mediated phase transition between LHCII-PsbS and its environment. This could act as the driving force to sort LHCII into photoprotective nanodomains in the thylakoid membrane. This work shows an example of the key role of the hydrophobic mismatch process in regulating membrane protein function in plants.
Topics: Thylakoids; Hydrophobic and Hydrophilic Interactions; Light-Harvesting Protein Complexes; Photosynthesis; Photosystem II Protein Complex; Galactolipids; Light
PubMed: 38759103
DOI: 10.1021/jacs.4c05220 -
PloS One 2024Microalgae's ability to mitigate flue gas is an attractive technology that can valorize gas components through biomass conversion. However, tolerance and growth must be...
Microalgae's ability to mitigate flue gas is an attractive technology that can valorize gas components through biomass conversion. However, tolerance and growth must be ideal; therefore, acclimation strategies are suggested. Here, we compared the transcriptome and lipidome of Desmodesmus abundans strains acclimated to high CO2 (HCA) and low CO2 (LCA) under continuous supply of model flue gas (MFG) and incomplete culture medium (BG11-N-S). Initial growth and nitrogen consumption from MFG were superior in strain HCA, reaching maximum productivity a day before strain LCA. However, similar productivities were attained at the end of the run, probably because maximum photobioreactor capacity was reached. RNA-seq analysis during exponential growth resulted in 16,435 up-regulated and 4,219 down-regulated contigs in strain HCA compared to LCA. Most differentially expressed genes (DEGs) were related to nucleotides, amino acids, C fixation, central carbon metabolism, and proton pumps. In all pathways, a higher number of up-regulated contigs with a greater magnitude of change were observed in strain HCA. Also, cellular component GO terms of chloroplast and photosystems, N transporters, and secondary metabolic pathways of interest, such as starch and triacylglycerols (TG), exhibited this pattern. RT-qPCR confirmed N transporters expression. Lipidome analysis showed increased glycerophospholipids in strain HCA, while LCA exhibited glycerolipids. Cell structure and biomass composition also revealed strains differences. HCA possessed a thicker cell wall and presented a higher content of pigments, while LCA accumulated starch and lipids, validating transcriptome and lipidome data. Overall, results showed significant differences between strains, where characteristic features of adaptation and tolerance to high CO2 might be related to the capacity to maintain a higher flux of internal C, regulate intracellular acidification, active N transporters, and synthesis of essential macromolecules for photosynthetic growth.
Topics: Carbon Dioxide; Transcriptome; Acclimatization; Lipidomics; Microalgae; Gene Expression Profiling; Photosynthesis; Lipid Metabolism; Chlorophyceae
PubMed: 38758755
DOI: 10.1371/journal.pone.0299780