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Rashkov GD, Stefanov MA, Yotsova EK, Borisova PB, Dobrikova AG, Apostolova EL. Exploring Nitric Oxide as a Regulator in Salt Tolerance: Insights into Photosynthetic Efficiency in Maize. PLANTS (BASEL, SWITZERLAND) 2024; 13:1312. [PMID: 38794383 PMCID: PMC11125177 DOI: 10.3390/plants13101312] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/04/2024] [Revised: 04/29/2024] [Accepted: 05/08/2024] [Indexed: 05/26/2024]
Abstract
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 (Zea mays 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 F735/F685). 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 QA- reoxidation. The data also revealed that SNP protects the rate constants for two pathways of QA- reoxidation (k1 and k2) from the changes caused by NaCl treatment alone. Additionally, there is a predominance of QA- interaction with plastoquinone in comparison to the recombination of electrons in QA QB- 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 S0 state, i.e., protects the initial S0-S1 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 (PIABS) 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.
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Affiliation(s)
| | | | | | | | | | - Emilia L. Apostolova
- Institute of Biophysics and Biomedical Engineering, Bulgarian Academy of Sciences, Acad. G. Bonchev Str., Bl. 21, 1113 Sofia, Bulgaria; (G.D.R.); (M.A.S.); (E.K.Y.); (P.B.B.); (A.G.D.)
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Stefanov MA, Rashkov GD, Borisova PB, Apostolova EL. Changes in Photosystem II Complex and Physiological Activities in Pea and Maize Plants in Response to Salt Stress. PLANTS (BASEL, SWITZERLAND) 2024; 13:1025. [PMID: 38611554 PMCID: PMC11013719 DOI: 10.3390/plants13071025] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/05/2024] [Revised: 03/26/2024] [Accepted: 04/01/2024] [Indexed: 04/14/2024]
Abstract
Salt stress significantly impacts the functions of the photosynthetic apparatus, with varying degrees of damage to its components. Photosystem II (PSII) is more sensitive to environmental stresses, including salinity, than photosystem I (PSI). This study investigated the effects of different salinity levels (0 to 200 mM NaCl) on the PSII complex in isolated thylakoid membranes from hydroponically grown pea (Pisum sativum L.) and maize (Zea mays L.) plants treated with NaCl for 5 days. The data revealed that salt stress inhibits the photochemical activity of PSII (H2O → BQ), affecting the energy transfer between the pigment-protein complexes of PSII (as indicated by the fluorescence emission ratio F695/F685), QA reoxidation, and the function of the oxygen-evolving complex (OEC). These processes were more significantly affected in pea than in maize under salinity. Analysis of the oxygen evolution curves after flashes and continuous illumination showed a stronger influence on the PSIIα than PSIIβ centers. The inhibition of oxygen evolution was associated with an increase in misses (α), double hits (β), and blocked centers (SB) and a decrease in the rate constant of turnover of PSII reaction centers (KD). Salinity had different effects on the two pathways of QA reoxidation in maize and pea. In maize, the electron flow from QA- to plastoquinone was dominant after treatment with higher NaCl concentrations (150 mM and 200 mM), while in pea, the electron recombination on QAQB- with oxidized S2 (or S3) of the OEC was more pronounced. Analysis of the 77 K fluorescence emission spectra revealed changes in the ratio of the light-harvesting complex of PSII (LHCII) monomers and trimers to LHCII aggregates after salt treatment. There was also a decrease in pigment composition and an increase in oxidative stress markers, membrane injury index, antioxidant activity (FRAP assay), and antiradical activity (DPPH assay). These effects were more pronounced in pea than in maize after treatment with higher NaCl concentrations (150 mM-200 mM). This study provides insights into how salinity influences the processes in the donor and acceptor sides of PSII in plants with different salt sensitivity.
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Affiliation(s)
- Martin A Stefanov
- Institute of Biophysics and Biomedical Engineering, Bulgarian Academy of Sciences, Acad. G. Bonchev Str., Bl. 21, 1113 Sofia, Bulgaria
| | - Georgi D Rashkov
- Institute of Biophysics and Biomedical Engineering, Bulgarian Academy of Sciences, Acad. G. Bonchev Str., Bl. 21, 1113 Sofia, Bulgaria
| | - Preslava B Borisova
- Institute of Biophysics and Biomedical Engineering, Bulgarian Academy of Sciences, Acad. G. Bonchev Str., Bl. 21, 1113 Sofia, Bulgaria
| | - Emilia L Apostolova
- Institute of Biophysics and Biomedical Engineering, Bulgarian Academy of Sciences, Acad. G. Bonchev Str., Bl. 21, 1113 Sofia, Bulgaria
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Rashkov GD, Stefanov MA, Yotsova EK, Borisova PB, Dobrikova AG, Apostolova EL. Impact of Sodium Nitroprusside on the Photosynthetic Performance of Maize and Sorghum. PLANTS (BASEL, SWITZERLAND) 2023; 13:118. [PMID: 38202426 PMCID: PMC10781006 DOI: 10.3390/plants13010118] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/29/2023] [Revised: 12/26/2023] [Accepted: 12/29/2023] [Indexed: 01/12/2024]
Abstract
Nitric oxide (NO) is an important molecule in regulating plant growth, development and photosynthetic performance. This study investigates the impact of varying concentrations (0-300 µM) of sodium nitroprusside (SNP, a donor of NO) on the functions of the photosynthetic apparatus in sorghum (Sorghum bicolor L. Albanus) and maize (Zea mays L. Kerala) under physiological conditions. Analysis of the chlorophyll fluorescence signals (using PAM and the JIP-test) revealed an increased amount of open PSII reaction centers (qP increased), but it did not affect the number of active reaction centers per PSII antenna chlorophyll (RC/ABS). In addition, the smaller SNP concentrations (up to 150 μM) alleviated the interaction of QA with plastoquine in maize, while at 300 μM it predominates the electron recombination on QAQB-, with the oxidized S2 (or S3) states of oxygen evolving in complex ways in both studied plant species. At the same time, SNP application stimulated the electron flux-reducing end electron acceptors at the PSI acceptor side per reaction center (REo/RC increased up to 26%) and the probability of their reduction (φRo increased up to 20%). An increase in MDA (by about 30%) and H2O2 contents was registered only at the highest SNP concentration (300 µM). At this concentration, SNP differentially affected the amount of P700+ in studied plant species, i.e., it increased (by 10%) in maize but decreased (by 16%) in sorghum. The effects of SNP on the functions of the photosynthetic apparatus were accompanied by an increase in carotenoid content in both studied plants. Additionally, data revealed that SNP-induced changes in the photosynthetic apparatus differed between maize and sorghum, suggesting species specificity for SNP's impact on plants.
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Affiliation(s)
| | | | | | | | | | - Emilia L. Apostolova
- Institute of Biophysics and Biomedical Engineering, Bulgarian Academy of Sciences, Acad. G. Bonchev Str., Bl. 21, 1113 Sofia, Bulgaria; (G.D.R.); (M.A.S.); (E.K.Y.); (P.B.B.); (A.G.D.)
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Shao J, Tang W, Huang K, Ding C, Wang H, Zhang W, Li R, Aamer M, Hassan MU, Elnour RO, Hashem M, Huang G, Qari SH. How Does Zinc Improve Salinity Tolerance? Mechanisms and Future Prospects. PLANTS (BASEL, SWITZERLAND) 2023; 12:3207. [PMID: 37765371 PMCID: PMC10534951 DOI: 10.3390/plants12183207] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/01/2023] [Revised: 08/24/2023] [Accepted: 08/28/2023] [Indexed: 09/29/2023]
Abstract
Salinity stress (SS) is a serious abiotic stress and a major constraint to agricultural productivity across the globe. High SS negatively affects plant growth and yield by altering soil physio-chemical properties and plant physiological, biochemical, and molecular processes. The application of micronutrients is considered an important practice to mitigate the adverse effects of SS. Zinc (Zn) is an important nutrient that plays an imperative role in plant growth, and it could also help alleviate the effects of salt stress. Zn application improves seed germination, seedling growth, water uptake, plant water relations, nutrient uptake, and nutrient homeostasis, therefore improving plant performance and saline conditions. Zn application also protects the photosynthetic apparatus from salinity-induced oxidative stress and improves stomata movement, chlorophyll synthesis, carbon fixation, and osmolytes and hormone accumulation. Moreover, Zn application also increases the synthesis of secondary metabolites and the expression of stress responsive genes and stimulates antioxidant activities to counter the toxic effects of salt stress. Therefore, to better understand the role of Zn in plants under SS, we have discussed the various mechanisms by which Zn induces salinity tolerance in plants. We have also identified diverse research gaps that must be filled in future research programs. The present review article will fill the knowledge gaps on the role of Zn in mitigating salinity stress. This review will also help readers to learn more about the role of Zn and will provide new suggestions on how this knowledge can be used to develop salt tolerance in plants by using Zn.
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Affiliation(s)
- Jinhua Shao
- China Guangxi Key Laboratory of Water Engineering Materials and Structures, Guangxi Hydraulic Research Institute, Nanning 530023, China; (J.S.); (W.T.); (K.H.); (C.D.); (W.Z.)
- Research Center on Ecological Sciences, Jiangxi Agricultural University, Nanchang 330045, China; (M.A.); (M.U.H.); (G.H.)
| | - Wei Tang
- China Guangxi Key Laboratory of Water Engineering Materials and Structures, Guangxi Hydraulic Research Institute, Nanning 530023, China; (J.S.); (W.T.); (K.H.); (C.D.); (W.Z.)
| | - Kai Huang
- China Guangxi Key Laboratory of Water Engineering Materials and Structures, Guangxi Hydraulic Research Institute, Nanning 530023, China; (J.S.); (W.T.); (K.H.); (C.D.); (W.Z.)
| | - Can Ding
- China Guangxi Key Laboratory of Water Engineering Materials and Structures, Guangxi Hydraulic Research Institute, Nanning 530023, China; (J.S.); (W.T.); (K.H.); (C.D.); (W.Z.)
| | - Haocheng Wang
- China Guangxi Key Laboratory of Water Engineering Materials and Structures, Guangxi Hydraulic Research Institute, Nanning 530023, China; (J.S.); (W.T.); (K.H.); (C.D.); (W.Z.)
- Research Center on Ecological Sciences, Jiangxi Agricultural University, Nanchang 330045, China; (M.A.); (M.U.H.); (G.H.)
| | - Wenlong Zhang
- China Guangxi Key Laboratory of Water Engineering Materials and Structures, Guangxi Hydraulic Research Institute, Nanning 530023, China; (J.S.); (W.T.); (K.H.); (C.D.); (W.Z.)
- Research Center on Ecological Sciences, Jiangxi Agricultural University, Nanchang 330045, China; (M.A.); (M.U.H.); (G.H.)
| | - Ronghui Li
- College of Civil Engineering and Architecture, Guangxi University, Nanning 530004, China
| | - Muhammad Aamer
- Research Center on Ecological Sciences, Jiangxi Agricultural University, Nanchang 330045, China; (M.A.); (M.U.H.); (G.H.)
| | - Muhammad Umair Hassan
- Research Center on Ecological Sciences, Jiangxi Agricultural University, Nanchang 330045, China; (M.A.); (M.U.H.); (G.H.)
| | - Rehab O. Elnour
- Biology Department, Faculty of Sciences and Arts, King Khalid University, Dahran Al-Janoub, Abha 64353, Saudi Arabia;
| | - Mohamed Hashem
- Department of Biology, College of Science, King Khalid University, Abha 61413, Saudi Arabia;
| | - Guoqin Huang
- Research Center on Ecological Sciences, Jiangxi Agricultural University, Nanchang 330045, China; (M.A.); (M.U.H.); (G.H.)
| | - Sameer H. Qari
- Department of Biology, Al-Jumum University College, Umm Al-Qura University, Makkah 21955, Saudi Arabia;
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Apostolova EL. Molecular Mechanisms of Plant Defense against Abiotic Stress. Int J Mol Sci 2023; 24:10339. [PMID: 37373486 DOI: 10.3390/ijms241210339] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2023] [Accepted: 06/08/2023] [Indexed: 06/29/2023] Open
Abstract
The climatic changes and anthropogenic factors in recent decades (global warming, drought, salinity, extreme temperature, environmental pollution) have led to an increase in the negative impact of environmental factors on plants. Abiotic stress strongly influences the important processes of plants and thus affects their growth and development. The effects of stressors on the plants depend on the intensity, frequency, and duration of stress, plant species as well as a combination of various stressors. Plants have developed different mechanisms to limit adverse environmental conditions. In the publications in this Special Issue, Molecular Mechanisms of Plant Defense against Abiotic Stress, new information on plant defense mechanisms against abiotic and biotic stress is presented. The studies help us better understand plants' protection mechanisms again global climate change.
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Affiliation(s)
- Emilia L Apostolova
- Institute of Biophysics and Biomedical Engineering, Bulgarian Academy of Sciences, Acad. G. Bonchev Str., Bl. 21, 1113 Sofia, Bulgaria
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