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Iwuala E, Olajide O, Abiodun I, Odjegba V, Utoblo O, Ajewole T, Oluwajobi A, Uzochukwu S. Silicon ameliorates cadmium (Cd) toxicity in pearl millet by inducing antioxidant defense system. Heliyon 2024; 10:e25514. [PMID: 38333779 PMCID: PMC10850601 DOI: 10.1016/j.heliyon.2024.e25514] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2023] [Revised: 01/17/2024] [Accepted: 01/29/2024] [Indexed: 02/10/2024] Open
Abstract
Cadmium (Cd) stress is a significant environmental pollutant that can negatively impact crop yield and growth, and is a serious global issue. However, silicon (Si) has been shown to have a potential function in alleviating the effects of several abiotic stress conditions on crops, including Cd stress. This study investigated the effectiveness of applying silicon to soil as a method for reducing cadmium toxicity in pearl millet (IP14599) seedlings. Seeds of IP14599 were treated with Si + Cd element which cumulated to a combination of 9 treatments. Different Cd concentration of (0, 200, and 300 mg/kg-1) was taken and manually mixed into a sieved soil prior to planting and Si (0, 100 and 200 mg/kg-1) was selectively introduced till after attaining 12 days of seedling emergence. The physiochemical parameters of Cd stressed plants investigated includes chlorophyll, gas exchange attributes, proline, relative water contents, malondialdehyde (MDA) content and antioxidant enzymes (superoxide dismutase (SOD),catalase (CAT), ascorbate peroxidase (APX), peroxidase (POD). Our result revealed that the metal (Cd) caused serious oxidative impairment thereby reducing photosynthetic performance, increased activity of MDA and Cd content in the roots and leaves of IP14599.In addition, Si increased the growth pattern and antioxidant defense action thereby mitigating the Cd toxicity. The results revealed that at Si 200, Si significantly increased the chlorophyll, carotenoids and plant height at 122 %, 69 % and 128 % under the Cd 200 and Cd 300 mg/kg-1 treatment, respectively. The single treatment at Si100 and Si 200 decreased ROS by 29 %, and 37 % respectively and MDA decreased by 33 % and 43 % in contrast to Cd 200 and 300 treatments, respectively. However, Si200 showed significant increase in the activities of APX 97 %, SOD by 89 %, CAT 35 % and POD 86 % as compared to single Si, Cd or combine Cd + Si treatment. Also, a gradual decline in Cd level in both the leaf and root was present when exposed to high concentrations of Si at Si200 and 300 mg/kg-1. Our findings revealed that Si might significantly increase the capacity to tolerate Cd stress in crop plants. Therefore, the study revealed that Si has the potential to alleviate Cd-induced toxicity by reducing Cd assimilation and enhancing the growth attributes of IP14599 plants.
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Affiliation(s)
- Emmanuel Iwuala
- Department of Plant Science and Biotechnology, Federal University Oye Ekiti, Nigeria
| | - Olubunmi Olajide
- Department of Landscape and Horticulture, Ekiti State University, Ekiti, Nigeria
| | - Isaika Abiodun
- Department of Plant Science and Biotechnology, Federal University Oye Ekiti, Nigeria
| | - Victor Odjegba
- Department of Botany, University of Lagos, Akoka, Yaba, Lagos State, Nigeria
| | - Obaiya Utoblo
- Department of Plant Science and Biotechnology, University of Jos, Plateau State, Nigeria
| | - Tolulope Ajewole
- Department of Plant Science and Biotechnology, Federal University Oye Ekiti, Nigeria
| | - Ayoola Oluwajobi
- Department of Plant Science and Biotechnology, Federal University Oye Ekiti, Nigeria
| | - Sylvia Uzochukwu
- Department of Plant Science and Biotechnology, Federal University Oye Ekiti, Nigeria
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Santos JDS, Pontes MDS, de Souza MB, Fernandes SY, Azevedo RA, de Arruda GJ, Santiago EF. Toxicity of bisphenol A (BPA) and its analogues BPF and BPS on the free-floating macrophyte Salvinia biloba. CHEMOSPHERE 2023; 343:140235. [PMID: 37734497 DOI: 10.1016/j.chemosphere.2023.140235] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/02/2023] [Revised: 09/17/2023] [Accepted: 09/19/2023] [Indexed: 09/23/2023]
Abstract
Evidence linking the toxicity of bisphenol A (BPA) to environmental and public-health issues has led to restrictions on its use. This compound has been gradually replaced with analogues proposed as a safer alternative, normally bisphenol F (BPF) and bisphenol S (BPS), but these substitutes are structurally almost identical to BPA, suggesting they may pose similar risks. The effects of BPA and these analogues were compared for antioxidant activity, lipid peroxidation, free-radical generation, photosynthetic pigments, and chlorophyll fluorescence in Salvinia biloba Raddi (S. biloba) plants exposed to environmentally relevant and sublethal concentrations (1, 10, 50, 100 and 150 μM). Bisphenol exposure promoted alterations in most of the physiological parameters investigated, with BPS toxicity differing slightly from that of the analogues. Furthermore, S. biloba removed similar levels of BPA and BPF from aqueous solutions with ≈70% removed at the 150 μM concentration, while BPS was less effectively removed, with only 23% removed at 150 μM. These findings show that high concentrations of bisphenols (10≥) are toxic to S. biloba, and even typical environmental levels (≤1 μM) can induce metabolic changes in plants, bringing to light that both BPA and its substitutes BPF and BPS pose risks to aquatic ecosystems.
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Affiliation(s)
- Jaqueline da Silva Santos
- Genetics Department, Escola Superior de Agricultura Luiz de Queiroz (ESALQ), Universidade de São Paulo (USP), Piracicaba, SP, Brazil.
| | - Montcharles da Silva Pontes
- Natural Resources Program, Centro de Estudos em Recursos Naturais (CERNA), Universidade Estadual de Mato Grosso do Sul (UEMS), Dourados, MS, Brazil; Research and Development Sector (R&D), Agróptica Instrumentation and Services Ltda (AGROPTICA), São Carlos, SP, Brazil
| | - Matheus Bispo de Souza
- Graduate Program in Chemistry, Analytics Department, Universidade Estadual de São Paulo (UNESP), Araraquara, SP, Brazil
| | - Simone Yasuda Fernandes
- Natural Resources Program, Centro de Estudos em Recursos Naturais (CERNA), Universidade Estadual de Mato Grosso do Sul (UEMS), Dourados, MS, Brazil
| | - Ricardo Antunes Azevedo
- Genetics Department, Escola Superior de Agricultura Luiz de Queiroz (ESALQ), Universidade de São Paulo (USP), Piracicaba, SP, Brazil
| | - Gilberto José de Arruda
- Natural Resources Program, Centro de Estudos em Recursos Naturais (CERNA), Universidade Estadual de Mato Grosso do Sul (UEMS), Dourados, MS, Brazil
| | - Etenaldo Felipe Santiago
- Natural Resources Program, Centro de Estudos em Recursos Naturais (CERNA), Universidade Estadual de Mato Grosso do Sul (UEMS), Dourados, MS, Brazil
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Che Y, Fan D, Teng Z, Yao T, Wang Z, Zhang H, Sun G, Zhang H, Chow WS. Potassium alleviates over-reduction of the photosynthetic electron transport chain and helps to maintain photosynthetic function under salt-stress. PHYSIOLOGIA PLANTARUM 2023; 175:e13981. [PMID: 37616008 DOI: 10.1111/ppl.13981] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/17/2022] [Revised: 05/11/2023] [Accepted: 07/15/2023] [Indexed: 08/25/2023]
Abstract
Potassium ions enhance photosynthetic tolerance to salt stress. We hypothesized that potassium ions, by minimizing the trans-thylakoid proton diffusion potential difference, can alleviate over-reduction of the photosynthetic electron transport chain and maintain the functionality of the photosynthetic apparatus. This study investigated the effects of exogenous potassium on the transcription level and activity of proteins related to the photosynthetic electron-transport chain of tobacco seedlings under salt stress. Salt stress retarded the growth of seedlings and caused an outflow of potassium ions from the chloroplast. It also lowered qP (indicator of the oxidation state of QA , the primary quinone electron acceptor in Photosystem II (PSII) and YPSII (average photochemical yield of PSII in the light-adapted state) while increasing YNO+NF (nonregulatory energy dissipation in functional and nonfunctional PSII), accompanied by decreased expression of most light-harvesting, energy-transduction, and electron-transport genes. However, exogenous potassium prevented these effects due to NaCl. Interestingly, lincomycin (an inhibitor of the synthesis of chloroplast-encoded proteins in PSII) significantly diminished the alleviation effect of exogenous potassium on salt stress. We attribute the comprehensive NaCl-induced downregulation of transcription and photosynthetic activities to retrograde signaling induced by reactive oxygen species. There probably exist at least two types of retrograde signaling induced by reactive oxygen species, distinguished by their sensitivity to lincomycin. Exogenous potassium appears to exert its primary effect by ameliorating the trans-thylakoid proton diffusion potential difference via a potassium channel, thereby accelerating ATP synthesis and carbon assimilation, alleviating over-reduction of the photosynthetic electron transport chain, and maintaining the functionality of photosynthetic proteins.
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Affiliation(s)
- Yanhui Che
- College of Life Sciences, Northeast Forestry University, Harbin, China
| | - Dayong Fan
- College of Forestry, Beijing Forestry University, Beijing, China
| | - Zhiyuan Teng
- College of Life Sciences, Northeast Forestry University, Harbin, China
| | - Tongtong Yao
- College of Life Sciences, Northeast Forestry University, Harbin, China
| | - Zihan Wang
- College of Life Sciences, Northeast Forestry University, Harbin, China
| | - Hongbo Zhang
- College of Life Sciences, Northeast Forestry University, Harbin, China
| | - Guangyu Sun
- College of Life Sciences, Northeast Forestry University, Harbin, China
| | - Huihui Zhang
- College of Life Sciences, Northeast Forestry University, Harbin, China
| | - Wah Soon Chow
- Division of Plant Sciences, Research School of Biology, Australian National University, Canberra, Australia
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Balasubramaniam T, Shen G, Esmaeili N, Zhang H. Plants' Response Mechanisms to Salinity Stress. PLANTS (BASEL, SWITZERLAND) 2023; 12:2253. [PMID: 37375879 DOI: 10.3390/plants12122253] [Citation(s) in RCA: 23] [Impact Index Per Article: 23.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/19/2023] [Revised: 05/29/2023] [Accepted: 05/31/2023] [Indexed: 06/29/2023]
Abstract
Soil salinization is a severe abiotic stress that negatively affects plant growth and development, leading to physiological abnormalities and ultimately threatening global food security. The condition arises from excessive salt accumulation in the soil, primarily due to anthropogenic activities such as irrigation, improper land uses, and overfertilization. The presence of Na⁺, Cl-, and other related ions in the soil above normal levels can disrupt plant cellular functions and lead to alterations in essential metabolic processes such as seed germination and photosynthesis, causing severe damage to plant tissues and even plant death in the worst circumstances. To counteract the effects of salt stress, plants have developed various mechanisms, including modulating ion homeostasis, ion compartmentalization and export, and the biosynthesis of osmoprotectants. Recent advances in genomic and proteomic technologies have enabled the identification of genes and proteins involved in plant salt-tolerance mechanisms. This review provides a short overview of the impact of salinity stress on plants and the underlying mechanisms of salt-stress tolerance, particularly the functions of salt-stress-responsive genes associated with these mechanisms. This review aims at summarizing recent advances in our understanding of salt-stress tolerance mechanisms, providing the key background knowledge for improving crops' salt tolerance, which could contribute to the yield and quality enhancement in major crops grown under saline conditions or in arid and semiarid regions of the world.
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Affiliation(s)
| | - Guoxin Shen
- Zhejiang Academy of Agricultural Sciences, Hangzhou 310021, China
| | - Nardana Esmaeili
- Department of Biological Sciences, Texas Tech University, Lubbock, TX 79409, USA
| | - Hong Zhang
- Department of Biological Sciences, Texas Tech University, Lubbock, TX 79409, USA
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Awan SA, Khan I, Rizwan M, Irshad MA, Xiaosan W, Zhang X, Huang L. Reduction in the cadmium (Cd) accumulation and toxicity in pearl millet (Pennisetum glaucum L.) by regulating physio-biochemical and antioxidant defense system via soil and foliar application of melatonin. ENVIRONMENTAL POLLUTION (BARKING, ESSEX : 1987) 2023; 328:121658. [PMID: 37075919 DOI: 10.1016/j.envpol.2023.121658] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/26/2023] [Revised: 03/12/2023] [Accepted: 04/16/2023] [Indexed: 05/03/2023]
Abstract
Cadmium (Cd) is among the toxic pollutants that harms the both animals and plants. The natural antioxidant, melatonin can improve Cd-stress tolerance but its potential role in reducing Cd stress and resilience mechanisms in pearl millet (Pennisetum glaucum L.) is remain unclear. The present study suggests that Cd causes severe oxidative damage by decreasing photosynthesis, and increasing reactive oxygen species (ROS), malondialdehyde content (MDA), and Cd content in different parts of pearl millet. However, exogenous melatonin (soil application and foliar treatment) mitigated the Cd toxicity and enhanced the growth, antioxidant defense system, and differentially regulated the expression of antioxidant-responsive genes i. e superoxide dismutase SOD-[Fe] 2, Fe-superoxide dismutase, Peroxiredoxin 2C, and L-ascorbate peroxidase-6. The results showed that foliar melatonin at F-200/50 significantly increased the plant height, chlorophyll a, b, a+b and carotenoids by 128%, 121%, 150%, 122%, and 69% over the Cd treatment, respectively. The soil and foliar melatonin at S-100/50 and F-100/50 reduced the ROS by 36%, and 44%, and MDA by 42% and 51% over the Cd treatment, respectively. Moreover, F200/50 significantly boosted the activities of antioxidant enzymes i. e SOD by 141%, CAT 298%, POD 117%, and APX 155% over the Cd treatment. Similarly, a significant reduction in Cd content in root, stem, and leaf was found on exposure to higher concentrations of exogenous melatonin. These findings suggest that exogenous melatonin may significantly and differentially improve the tolerance to Cd stress in crop plants. However, field applications, type of plant species, concentration of dose, and type of stress may vary with the degree of tolerance in crop plants.
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Affiliation(s)
- Samrah Afzal Awan
- College of Grassland Science & Technology, Sichuan Agricultural University, Chengdu, 611130, China; College of Agronomy, Sichuan Agricultural University, Chengdu, 611130, China
| | - Imran Khan
- College of Grassland Science & Technology, Sichuan Agricultural University, Chengdu, 611130, China; State Key Laboratory of Herbage Improvement and Grassland Agro-Ecosystems, Key Laboratory of Grassland Livestock Industry Innovation, Ministry of Agriculture, College of Pastoral Agriculture Science and Technology, Lanzhou University, Lanzhou 730020, China
| | - Muhammad Rizwan
- Department of Environmental Sciences, Government College University Faisalabad, Faisalabad, Pakistan
| | - Muhammad Atif Irshad
- Department of Environmental Sciences, The University of Lahore, Lahore, Pakistan
| | - Wang Xiaosan
- College of Grassland Science & Technology, Sichuan Agricultural University, Chengdu, 611130, China
| | - Xinquan Zhang
- College of Grassland Science & Technology, Sichuan Agricultural University, Chengdu, 611130, China
| | - Linkai Huang
- College of Grassland Science & Technology, Sichuan Agricultural University, Chengdu, 611130, China.
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Fu J, Li L, Wang S, Yu N, Shan H, Shi Z, Li F, Zhong X. Effect of gibberellic acid on photosynthesis and oxidative stress response in maize under weak light conditions. FRONTIERS IN PLANT SCIENCE 2023; 14:1128780. [PMID: 36875610 PMCID: PMC9978513 DOI: 10.3389/fpls.2023.1128780] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 12/21/2022] [Accepted: 02/03/2023] [Indexed: 06/18/2023]
Abstract
Gibberellin (GA) is an important endogenous hormone involved in plant responses to abiotic stresses. Experiments were conducted at the Research and Education Center of Agronomy, Shenyang Agricultural University (Shenyang, China) in 2021.We used a pair of near-isogenic inbred maize lines comprising, SN98A (light-sensitive inbred line) and SN98B (light-insensitive inbred line) to study the effects of exogenous gibberellin A3 (GA3) application on different light-sensitive inbred lines under weak light conditions. The concentration of GA3 was selected as 20, 40 and 60 mg L-1. After shade treatment, the photosynthetic physiological indexes of SN98A were always lower than SN98B, and the net photosynthetic rate of SN98A was 10.12% lower than SN98B on the 20th day after shade treatment. GA3 treatments significantly reduced the barren stalk ratios in SN98A and improved its seed setting rates by increasing the net photosynthetic rate (Pn), transpiration rate (Tr), stomatal conductance (Gs), photosynthetic pigment contents, photochemical efficiency of photosystem II (PS II) (Fv/Fm), photochemical quenching coefficient (qP), effective quantum yield of PSII photochemistry (ΦPSII), and antioxidant enzyme activities, where the most effective treatment was 60 mg L-1GA3. Compared with CK group, the seed setting rate increased by 33.87%. GA3 treatment also regulated the metabolism of reactive oxygen species (ROS) and reduced the superoxide anion ( O 2 - ) production rate, H2O2 content, and malondialdehyde content. The superoxide anion ( O 2 - ) production rate, H2O2 content and malondialdehyde content of SN98A sprayed with 60 mg L-1 GA3 decreased by 17.32%,10.44% and 50.33% compared with CK group, respectively. Compared with the control, GA3 treatment significantly (P < 0.05) increased the expression levels of APX and GR in SN98A, and APX, Fe-SOD, and GR in SN98B. Weak light stress decreased the expression of GA20ox2, which was related to gibberellin synthesis, and the endogenous gibberellin synthesis of SN98A. Weak light stress accelerated leaf senescence, and exogenous GA3 application inhibited the ROS levels in the leaves and maintained normal physiological functions in the leaves. These results indicate that exogenous GA3 enhances the adaptability of plants to low light stress by regulating photosynthesis, ROS metabolism and protection mechanisms, as well as the expression of key genes, which may be an economical and environmentally friendly method to solve the low light stress problem in maize production.
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Affiliation(s)
- Jianjun Fu
- Special Corn Institute, Shenyang Agricultural University, Shenyang, China
| | - Linlin Li
- Special Corn Institute, Shenyang Agricultural University, Shenyang, China
| | - Shuang Wang
- Special Corn Institute, Shenyang Agricultural University, Shenyang, China
| | - Na Yu
- Special Corn Institute, Shenyang Agricultural University, Shenyang, China
| | - Hong Shan
- Liaoning Dongya Seed Co., Ltd., Shenyang, China
| | - Zhensheng Shi
- Special Corn Institute, Shenyang Agricultural University, Shenyang, China
| | - Fenghai Li
- Special Corn Institute, Shenyang Agricultural University, Shenyang, China
| | - Xuemei Zhong
- Special Corn Institute, Shenyang Agricultural University, Shenyang, China
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Su Q, Sun Z, Liu Y, Lei J, Zhu W, Nanyan L. Physiological and comparative transcriptome analysis of the response and adaptation mechanism of the photosynthetic function of mulberry ( Morus alba L.) leaves to flooding stress. PLANT SIGNALING & BEHAVIOR 2022; 17:2094619. [PMID: 35786355 PMCID: PMC9255227 DOI: 10.1080/15592324.2022.2094619] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 06/08/2022] [Revised: 06/21/2022] [Accepted: 06/22/2022] [Indexed: 06/15/2023]
Abstract
Flooding has become one of the major abiotic stresses that seriously affects plant growth and development owing to changes in the global precipitation pattern. Mulberry (Morus alba L.) is a desirable tree spePhysocarpus amurensis Maxim andcies with high ecological and economic benefits. To reveal the response and adaptive mechanisms of the photosynthetic functions of mulberry leaves to flooding stress, chlorophyll synthesis, photosynthetic electron transfer and the Calvin cycle were investigated by physiological studies combined with an analysis of the transcriptome. Flooding stress inhibited the synthesis of chlorophyll (Chl) and decreased its content in mulberry leaves. The sensitivity of Chl a to flooding stress was higher than that of Chl b owing to the changes of CHLG (LOC21385082) and CAO (LOC21408165) that encode genes during chlorophyll synthesis. The levels of expression of Chl b reductase NYC (LOC112094996) and NYC (LOC21385774), which are involved in Chl b degradation, were upregulated on the fifteenth day of flooding, which accelerated the transformation of Chl b to Chl a, and upregulated the expression of PPH (LOC21385040) and PAO (LOC21395013). This accelerated the degradation of chlorophyll. Flooding stress significantly inhibited the photosynthetic function of mulberry leaves. A Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analysis of differentially expressed genes under different days of flooding stress indicated significant enrichment in Photosynthesis-antenna proteins (map00196), Photosynthesis (map00195) and Carbon fixation in photosynthetic organisms (map00710). On the fifth day of flooding, 7 and 5 genes that encode antenna proteins were identified on LHCII and LHCI, respectively. They were significantly downregulated, and the degree of downregulation increased as the trees were flooded longer. Therefore, the power of the leaves to capture solar energy and transfer this energy to the reaction center was reduced. The chlorophyll fluorescence parameters and related changes in the expression of genes in the transcriptome indicated that the PSII and PSI of mulberry leaves were damaged, and their activities decreased under flooding stress. On the fifth day of flooding, electron transfer on the PSII acceptor side of mulberry leaves was blocked, and the oxygen-evolving complex (OEC) on the donor side was damaged. On the tenth day of flooding, the thylakoid membranes of mulberry leaves were damaged. Five of the six coding genes that mapped to the OEC were significantly downregulated. Simultaneously, other coding genes located at the PSII reaction center and those located at the PSI reaction center, including Cytb6/f, PC, Fd, FNR and ATP, were also significantly downregulated. In addition, the gas exchange parameters (Pn, Gs, Tr, and Ci) of the leaves decreased after 10 days of flooding stress primarily owing to the stomatal factor. However, on the fifteenth day of flooding, the value for the intracellular concentration of CO2 was significantly higher than that on the tenth day of flooding. In addition, the differentially expressed genes identified in the Calvin cycle were significantly downregulated, suggesting that in addition to stomatal factors, non-stomatal factors were also important factors that mediated the decrease in the photosynthetic capacity of mulberry leaves. In conclusion, the inhibition of growth of mulberry plants caused by flooding stress was primarily related to the inhibition of chlorophyll synthesis, antenna proteins, photosynthetic electron transfer and the Calvin cycle. The results of this study provide a theoretical basis for the response and mechanism of adaptation of the photosynthetic function of mulberry to flooding stress.
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Affiliation(s)
- Quan Su
- College of Life Science, Guangxi Normal University, Guilin, Liaoning, China
| | - Zhiyu Sun
- College of Forestry, Shenyang Agricultural University, Shenyang, Guangxi, China
| | - Yuting Liu
- College of Forestry, Shenyang Agricultural University, Shenyang, Guangxi, China
| | - Jiawei Lei
- College of Forestry, Shenyang Agricultural University, Shenyang, Guangxi, China
| | - Wenxu Zhu
- College of Forestry, Shenyang Agricultural University, Shenyang, Guangxi, China
| | - Liao Nanyan
- Guangxi Fangcheng Golden Camellias National Nature Reserve, Guilin541006, Guangxi, China
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Li Y, Tian B, Wang Y, Wang J, Zhang H, Wang L, Sun G, Yu Y, Zhang H. The Transcription Factor MYB37 Positively Regulates Photosynthetic Inhibition and Oxidative Damage in Arabidopsis Leaves Under Salt Stress. FRONTIERS IN PLANT SCIENCE 2022; 13:943153. [PMID: 35903240 PMCID: PMC9315438 DOI: 10.3389/fpls.2022.943153] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 05/13/2022] [Accepted: 06/21/2022] [Indexed: 06/15/2023]
Abstract
MYB transcription factors (TFs) mediate plant responses and defenses to biotic and abiotic stresses. The effects of overexpression of MYB37, an R2R3 MYB subgroup 14 transcription factors in Arabidopsis thaliana, on chlorophyll content, chlorophyll fluorescence parameters, reactive oxygen species (ROS) metabolism, and the contents of osmotic regulatory substances were studied under 100 mM NaCl stress. Compared with the wild type (Col-0), MYB37 overexpression significantly alleviated the salt stress symptoms in A. thaliana plants. Chlorophyll a (Chl a) and chlorophyll b (Chl b) contents were significantly decreased in OE-1 and OE-2 than in Col-0. Particularly, the Chl a/b ratio was also higher in OE-1 and OE-2 than in Col-0 under NaCl stress. However, MYB37 overexpression alleviated the degradation of chlorophyll, especially Chl a. Salt stress inhibited the activities of PSII and PSI in Arabidopsis leaves, but did not affect the activity of PSII electron donor side oxygen-evolving complex (OEC). MYB37 overexpression increased photosynthesis in Arabidopsis by increasing PSII and PSI activities. MYB37 overexpression also promoted the transfer of electrons from Q A to Q B on the PSII receptor side of Arabidopsis under NaCl stress. Additionally, MYB37 overexpression increased Y(II) and Y(NPQ) of Arabidopsis under NaCl stress and decreased Y(NO). These results indicate that MYB37 overexpression increases PSII activity and regulates the proportion of energy dissipation in Arabidopsis leaves under NaCl stress, thus decreasing the proportion of inactivated reaction centers. Salt stress causes excess electrons and energy in the photosynthetic electron transport chain of Arabidopsis leaves, resulting in the release of reactive oxygen species (ROS), such as superoxide anion and hydrogen peroxide, leading to oxidative damage. Nevertheless, MYB37 overexpression reduced accumulation of malondialdehyde in Arabidopsis leaves under NaCl stress and alleviated the degree of membrane lipid peroxidation caused by ROS. Salt stress also enhanced the accumulation of soluble sugar (SS) and proline (Pro) in Arabidopsis leaves, thus reducing salt stress damage to plants. Salt stress also degraded soluble protein (SP). Furthermore, the accumulation of osmoregulation substances SS and Pro in OE-1 and OE-2 was not different from that in Col-0 since MYB37 overexpression in Arabidopsis OE-1, and OE-2 did not significantly affect plants under NaCl stress. However, SP content was significantly higher in OE-1 and OE-2 than in Col-0. These results indicate that MYB37 overexpression can alleviate the degradation of Arabidopsis proteins under NaCl stress, promote plant growth and improve salt tolerance.
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Affiliation(s)
- Yuanyuan Li
- Key Laboratory of Saline-alkali Vegetation Ecology Restoration, Ministry of Education, College of Life Sciences, Northeast Forestry University, Harbin, China
| | - Bei Tian
- Key Laboratory of Saline-alkali Vegetation Ecology Restoration, Ministry of Education, College of Life Sciences, Northeast Forestry University, Harbin, China
| | - Yue Wang
- Key Laboratory of Saline-alkali Vegetation Ecology Restoration, Ministry of Education, College of Life Sciences, Northeast Forestry University, Harbin, China
| | - Jiechen Wang
- Key Laboratory of Saline-alkali Vegetation Ecology Restoration, Ministry of Education, College of Life Sciences, Northeast Forestry University, Harbin, China
| | - Hongbo Zhang
- Key Laboratory of Saline-alkali Vegetation Ecology Restoration, Ministry of Education, College of Life Sciences, Northeast Forestry University, Harbin, China
| | - Lu Wang
- Key Laboratory of Saline-alkali Vegetation Ecology Restoration, Ministry of Education, College of Life Sciences, Northeast Forestry University, Harbin, China
| | - Guangyu Sun
- Key Laboratory of Saline-alkali Vegetation Ecology Restoration, Ministry of Education, College of Life Sciences, Northeast Forestry University, Harbin, China
| | - Yongtao Yu
- National Watermelon and Melon Improvement Center, Beijing Academy of Agriculture and Forestry Sciences, Key Laboratory of Biology and Genetic Improvement of Horticultural Crops (North China), Beijing Key Laboratory of Vegetable Germplasm Improvement, Beijing, China
| | - Huihui Zhang
- Key Laboratory of Saline-alkali Vegetation Ecology Restoration, Ministry of Education, College of Life Sciences, Northeast Forestry University, Harbin, China
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Screening of Key Indices and the Gene Transcriptional Regulation Analysis Related to Salt Tolerance in Salix matsudana Seedlings. FORESTS 2022. [DOI: 10.3390/f13050754] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Pot experiments were performed to comparatively study the differences in 16 salt tolerance indices between the seedlings of six Salix matsudana clones under the stress of various concentrations of NaCl (0, 0.1%, 0.3%, 0.5%, and 0.7%), including the salt injury index, shoot fresh weight, root fresh weight, leaf water content, relative conductivity, malondialdehyde content, and antioxidant enzyme activity. The salt-tolerant clones and key indices of salt tolerance were selected. Transcriptome sequencing analysis was performed on the selected salt-tolerant and salt-sensitive clones under salt stress, and the links between the physiological indices of salt tolerance and gene expression were analyzed. Results: (1) Superoxide dismutase (SOD), peroxidase (POD), chlorophyll, and net photosynthetic rate were closely related to the salt tolerance of Salix matsudana at the seedling stage. The regression equation was constructed as follows: salt tolerance index (y) = 0.224x10 + 0.216x11 + 0.127x12 + 0.191x7 − 0.187 (x10 = chlorophyll, x11 = SOD, x12 = POD, x7 = net photosynthetic rate). (2) The number of differentially expressed genes between the seedlings of salt-tolerant and salt-sensitive clones varied with the time of exposure (0 h, 4 h, 12 h, and 24 h) to 200 mmol·L−1 NaCl stress. The most differentially expressed genes in Sm172 were detected upon 24 h vs. 4 h of salt treatment, while the most in Sm6 were in the 24 h vs. 0 h comparison. Gene Ontology analysis and Kyoto Encyclopedia of Genes and Genomes analysis showed that several differentially expressed genes were involved in carotenoid biosynthesis and plant mitogen-activated protein kinase signaling pathways. The nine highly expressed transcription factor genes (Sm172-f2p30-2392, Sm172-f2p28-2386, Sm6-f8p60-2372, Sm6-f2p39-2263, Sm6-f16p60-2374, Sm6-f3p60-931, Sm6-f2p60-1067, Sm172-f3p54-1980, and Sm172-f3p54-1980) were closely correlated with the four key indices of salt tolerance. These genes could become genetic resources for salt tolerance breeding of Salix matsudana.
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Zahra N, Al Hinai MS, Hafeez MB, Rehman A, Wahid A, Siddique KHM, Farooq M. Regulation of photosynthesis under salt stress and associated tolerance mechanisms. PLANT PHYSIOLOGY AND BIOCHEMISTRY : PPB 2022; 178:55-69. [PMID: 35276596 DOI: 10.1016/j.plaphy.2022.03.003] [Citation(s) in RCA: 51] [Impact Index Per Article: 25.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/30/2021] [Revised: 02/12/2022] [Accepted: 03/03/2022] [Indexed: 05/24/2023]
Abstract
Photosynthesis is crucial for the survival of all living biota, playing a key role in plant productivity by generating the carbon skeleton that is the primary component of all biomolecules. Salinity stress is a major threat to agricultural productivity and sustainability as it can cause irreversible damage to photosynthetic apparatus at any developmental stage. However, the capacity of plants to become photosynthetically active under adverse saline conditions remains largely untapped. This study addresses this discrepancy by exploring the current knowledge on the impact of salinity on chloroplast operation, metabolism, chloroplast ultrastructure, and leaf anatomy, and highlights the dire consequences for photosynthetic machinery and stomatal conductance. We also discuss enhancing photosynthetic capacity by modifying and redistributing electron transport between photosystems and improving photosystem stability using genetic approaches, beneficial microbial inoculations, and root architecture changes to improve salt stress tolerance under field conditions. Understanding chloroplast operations and molecular engineering of photosynthetic genes under salinity stress will pave the way for developing salt-tolerant germplasm to ensure future sustainability by rehabilitating saline areas.
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Affiliation(s)
- Noreen Zahra
- Department of Botany, University of Agriculture, Faisalabad, 38040, Pakistan
| | - Marwa Sulaiman Al Hinai
- Department of Plant Sciences, College of Agricultural and Marine Sciences, Sultan Qaboos University, Al-Khoud 123, Oman
| | | | - Abdul Rehman
- Department of Agronomy, Faculty of Agriculture and Environment, The Islamia University of Bahawalpur, 63100, Bahawalpur, Pakistan
| | - Abdul Wahid
- Department of Botany, University of Agriculture, Faisalabad, 38040, Pakistan
| | - Kadambot H M Siddique
- The UWA Institute of Agriculture, The University of Western Australia, Perth, WA, 6001, Australia
| | - Muhammad Farooq
- Department of Plant Sciences, College of Agricultural and Marine Sciences, Sultan Qaboos University, Al-Khoud 123, Oman; The UWA Institute of Agriculture, The University of Western Australia, Perth, WA, 6001, Australia.
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Raja V, Wani UM, Wani ZA, Jan N, Kottakota C, Reddy MK, Kaul T, John R. Pyramiding ascorbate-glutathione pathway in Lycopersicum esculentum confers tolerance to drought and salinity stress. PLANT CELL REPORTS 2022; 41:619-637. [PMID: 34383122 DOI: 10.1007/s00299-021-02764-8] [Citation(s) in RCA: 13] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/05/2021] [Accepted: 07/30/2021] [Indexed: 06/13/2023]
Abstract
Stacking Glutathione-Ascorbate pathway genes (PgSOD, PgAPX, PgGR, PgDHAR and PgMDHAR) under stress inducible promoter RD29A imparts significant tolerance to drought and salinity stress in Solanum lycopersicum. Although the exposure of plants to different environmental stresses results in overproduction of reactive oxygen species (ROS), many plants have developed some unique systems to alleviate the ROS production and mitigate its deleterious effect. One of the key pathways that gets activated in plants is ascorbate glutathione (AsA-GSH) pathway. To demonstrate the effect of this pathway in tomato, we developed the AsA-GSH overexpression lines by stacking the genes of the AsA-GSH pathway genes isolated from Pennisetum glaucoma (Pg) including PgSOD, PgAPX, PgGR, PgDHAR and PgMDHAR under stress inducible promoter RD29A. The overexpression lines have an improved germination and seedling growth with concomitant elevation in the survival rate. The exposure of transgenic seedlings to varying stress regiments exhibited escalation in the antioxidant enzyme activity and lesser membrane damage as reflected by decreased electrolytic leakage and little accumulation of malondialdehyde and H2O2. Furthermore, the transgenic lines accumulated high levels of osmoprotectants with increase in the relative water content. The increased photosynthetic activity and enhanced gaseous exchange parameters further confirmed the enhanced tolerance of AsA-GSH overexpression lines. We concluded that pyramiding of AsA-GSH pathway genes is an effective strategy for developing stress resistant crops.
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Affiliation(s)
- Vaseem Raja
- Plant Molecular Biology Laboratory, Department of Botany, University of Kashmir, Srinagar, Kashmir, 190006, India
| | - Umer Majeed Wani
- Plant Molecular Biology Laboratory, Department of Botany, University of Kashmir, Srinagar, Kashmir, 190006, India
- Department of Biotechnology, University of Kashmir, Srinagar, 190006, India
| | - Zubair Ahmad Wani
- Department of Biotechnology, University of Kashmir, Srinagar, 190006, India
| | - Nelofer Jan
- Plant Molecular Biology Laboratory, Department of Botany, University of Kashmir, Srinagar, Kashmir, 190006, India
| | - Chandrasekhar Kottakota
- International Center for Genetic Engineering and Biotechnology (ICGEB), New Delhi, 1100067, India
| | - Malireddy K Reddy
- International Center for Genetic Engineering and Biotechnology (ICGEB), New Delhi, 1100067, India
| | - Tanushri Kaul
- International Center for Genetic Engineering and Biotechnology (ICGEB), New Delhi, 1100067, India
| | - Riffat John
- Plant Molecular Biology Laboratory, Department of Botany, University of Kashmir, Srinagar, Kashmir, 190006, India.
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Liu B, Zhang X, You X, Li Y, Long S, Wen S, Liu Q, Liu T, Guo H, Xu Y. Hydrogen sulfide improves tall fescue photosynthesis response to low-light stress by regulating chlorophyll and carotenoid metabolisms. PLANT PHYSIOLOGY AND BIOCHEMISTRY : PPB 2022; 170:133-145. [PMID: 34883320 DOI: 10.1016/j.plaphy.2021.12.002] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/26/2021] [Revised: 11/26/2021] [Accepted: 12/01/2021] [Indexed: 06/13/2023]
Abstract
Hydrogen sulfide (H2S), as a gaseous messenger molecule, plays critical roles in signal transduction and biological modulation. In the present study, the roles of H2S in regulating chlorophyll (Chl) and carotenoid (Car) contents to improve photosynthesis in tall fescue were investigated under low-light (LL) stress. Compared to control conditions, LL stress significantly reduced total biomass, net photosynthetic rate (Pn), maximal quantum yield of photosystem II (PSII) photochemistry (Fv/Fm), and the contents of Chl and Car. Under exogenous sodium hydrosulfide (NaHS, H2S donor) application, these parameters were enhanced, ultimately increasing photosynthesis. Moreover, exogenous H2S up-regulated the expression of chlorophyll biosynthesis genes while down-regulated chlorophyll degradation genes, resulting in increases in chlorophyll precursors. Components of carotenoids and expression of genes encoding biosynthesis and degradation enzymes varied similarly. Additionally, application exogenous H2S up-regulated expression of FaDES1 and FaDCD. Thus, it enhanced L-cysteine desulfhydrase 1 (DES1, EC 4.4.1.1) and D-cysteine desulfhydrase (DCD, EC 4.4.1.15) activities leading to elevated endogenous H2S. However, these responses were reversed by treatment with hypotaurine (HT, H2S scavenger). These results suggested that H2S is involved in regulating photosynthesis to improve LL tolerance via modulating Chl and Car metabolisms in tall fescue.
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Affiliation(s)
- Bowen Liu
- College of Grassland Agriculture, Northwest A&F University, Yangling, Shaanxi Province, 712100, PR China
| | - Xuhu Zhang
- College of Grassland Agriculture, Northwest A&F University, Yangling, Shaanxi Province, 712100, PR China
| | - Xiangkai You
- College of Grassland Agriculture, Northwest A&F University, Yangling, Shaanxi Province, 712100, PR China
| | - Youyue Li
- College of Grassland Agriculture, Northwest A&F University, Yangling, Shaanxi Province, 712100, PR China
| | - Si Long
- College of Grassland Agriculture, Northwest A&F University, Yangling, Shaanxi Province, 712100, PR China
| | - Suyun Wen
- College of Grassland Agriculture, Northwest A&F University, Yangling, Shaanxi Province, 712100, PR China
| | - Qian Liu
- College of Grassland Agriculture, Northwest A&F University, Yangling, Shaanxi Province, 712100, PR China
| | - Tieyuan Liu
- College of Grassland Agriculture, Northwest A&F University, Yangling, Shaanxi Province, 712100, PR China
| | - Huan Guo
- College of Grassland Agriculture, Northwest A&F University, Yangling, Shaanxi Province, 712100, PR China
| | - Yuefei Xu
- College of Grassland Agriculture, Northwest A&F University, Yangling, Shaanxi Province, 712100, PR China.
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Ding G, Yang Q, Ruan X, Si T, Yuan B, Zheng W, Xie Q, Souleymane OA, Wang X. Proteomics analysis of the effects for different salt ions in leaves of true halophyte Sesuvium portulacastrum. PLANT PHYSIOLOGY AND BIOCHEMISTRY : PPB 2022; 170:234-248. [PMID: 34920320 DOI: 10.1016/j.plaphy.2021.12.009] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/07/2021] [Revised: 12/07/2021] [Accepted: 12/09/2021] [Indexed: 05/25/2023]
Abstract
Sesuvium portulacastrum is a true halophyte and shows an optimal development under moderate salinity with large amounts of salt ions in its leaves. However, the specific proteins in response to salt ions are remained unknown. In this study, comparative physiological and proteomic analyses of different leaves subject to NaCl, KCl, NaNO3 and KNO3 were performed. Chlorophyll content was decreased under the above four kinds of salt treatments. Starch and soluble sugar contents changed differently under different salt treatments. A total of 53 differentially accumulated proteins (DAPs) were identified by mass spectrometry. Among them, 13, 25, 26 and 25 DAPs were identified after exposure to KCl, NaCl, KNO3, and NaNO3, respectively. These DAPs belong to 47 unique genes, and 37 of them are involved in protein-protein interactions. These DAPs displayed different expression patterns after treating with different salt ions. Functional annotation revealed they are mainly involved in photosynthesis, carbohydrate and energy metabolism, lipid metabolism, and biosynthesis of secondary metabolites. Genes and proteins showed different expression profiles under different salt treatments. Enzyme activity analysis indicated P-ATPase was induced by KCl, NaCl and NaNO3, V-ATPase was induced by KCl and NaCl, whereas V-PPase activity was significantly increased after application of KNO3, but sharply inhibited by NaCl. These results might deepen our understanding of responsive mechanisms in the leaves of S. portulacastrum upon different salt ions.
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Affiliation(s)
- Guohua Ding
- College of Life Sciences, Ministry of Education Key Laboratory for Ecology of Tropical Islands, Hainan Normal University, Haikou, Hainan, 571158, China
| | - Qian Yang
- South Subtropical Crop Research Institute, China Academy of Tropical Agricultural Sciences, China
| | - Xueyu Ruan
- College of Life Sciences, Ministry of Education Key Laboratory for Ecology of Tropical Islands, Hainan Normal University, Haikou, Hainan, 571158, China
| | - Tingting Si
- College of Life Sciences, Ministry of Education Key Laboratory for Ecology of Tropical Islands, Hainan Normal University, Haikou, Hainan, 571158, China
| | - Boxuan Yuan
- College of Life Sciences, Ministry of Education Key Laboratory for Ecology of Tropical Islands, Hainan Normal University, Haikou, Hainan, 571158, China; Key Laboratory of Xinjiang Phytomedicine Resource and Utilization of Ministry of Education, College of Life Sciences, Shihezi University, Shihezi, 832003, China
| | - Wenwei Zheng
- College of Life Sciences, Ministry of Education Key Laboratory for Ecology of Tropical Islands, Hainan Normal University, Haikou, Hainan, 571158, China
| | - Quanliang Xie
- Key Laboratory of Xinjiang Phytomedicine Resource and Utilization of Ministry of Education, College of Life Sciences, Shihezi University, Shihezi, 832003, China
| | - Ousmane Ahmat Souleymane
- College of Life Sciences, Ministry of Education Key Laboratory for Ecology of Tropical Islands, Hainan Normal University, Haikou, Hainan, 571158, China
| | - Xuchu Wang
- College of Life Sciences, Ministry of Education Key Laboratory for Ecology of Tropical Islands, Hainan Normal University, Haikou, Hainan, 571158, China.
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Liang XD, Shalapy M, Zhao SF, Liu JH, Wang JY. A stress-responsive transcription factor PeNAC1 regulating beta-D-glucan biosynthetic genes enhances salt tolerance in oat. PLANTA 2021; 254:130. [PMID: 34817644 DOI: 10.1007/s00425-021-03770-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/24/2021] [Accepted: 10/22/2021] [Indexed: 06/13/2023]
Abstract
A Populus euphratica NAC gene regulates (1,3; 1,4)-β-D-glucan content in oat developing seed and improves the spikelet number and grain number per spike in transgenic oat under salinity conditions Salinity is the major factor affecting the production and quality of oat, and improving oat salt tolerance to increase yield and quality is vital. (1,3;1,4)-β-D-glucan in Gramineae is the key component in response to various environmental signals, and it is the most important functional ingredient in oat grain. The NAC transcription factors are important candidate genes used in genetic engineering to improve plant abiotic stress tolerance. In this study, we introduced Populus euphratica PeNAC1, controlled by its own promoter, into hexaploid cultivated oat and produced six transgenic lines. Compared to the non-transgenic control, the expression of PeNAC1 significantly improved the seed germination rate, seedling survival rate, and leaf chlorophyll content in the transgenic plants under salt stress. These physiological changes increased the spikelet number and grain number per spike in the transgenic oat under salinity conditions and reduced the yield loss per plant. The results indicated that the heterologous expression of PeNAC1 plays an effective role in improving the salt tolerance in transgenic oat. In addition, overexpressing PeNAC1 significantly increased the (1,3;1,4)-β-D-glucan content as well as the expression level of the (1,3;1,4)-β-D-glucan biosynthetic genes AsCslF3, AsCslF6, and AsCslF9 in the transgenic lines under salt stress, which suggested that PeNAC1 regulates the synthesis of (1,3;1,4)-β-D-glucan. Our research should assist in the discovery of the diverse action modes of NAC proteins, while PeNAC1 will be useful for improving the salt tolerance and quality of oat through molecular breeding.
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Affiliation(s)
- Xiao-Dong Liang
- XinJiang Academy of Agricultural Sciences Grain Crops Institute, No. 403 Nanchang Road, Urumqi, 830091, China
- Biotechnology Research Institute of Chinese Academy of Agricultural Sciences, No. 12 Zhong Guan Cun South Street, Beijing, 100081, China
| | - Mohamed Shalapy
- XinJiang Academy of Agricultural Sciences Grain Crops Institute, No. 403 Nanchang Road, Urumqi, 830091, China
| | - Shi-Feng Zhao
- Zhangjiakou Academy of Agricultural Sciences, Zhangjiakou, 075000, China
| | - Jing-Hui Liu
- Inner Mongolia Agriculture University, No. 275 Xue Yuan East Street, Hohhot, 010019, China.
| | - Jun-Ying Wang
- XinJiang Academy of Agricultural Sciences Grain Crops Institute, No. 403 Nanchang Road, Urumqi, 830091, China.
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Genetic Determinants of Stress Resistance in Desiccated Salmonella enterica. Appl Environ Microbiol 2021; 87:e0168321. [PMID: 34586905 DOI: 10.1128/aem.01683-21] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Enteric pathogens, including Salmonella, are capable of long-term survival after desiccation and resist heat treatments that are lethal to hydrated cells. The mechanisms of dry-heat resistance differ from those of wet-heat resistance. To elucidate the mechanisms of dry-heat resistance in Salmonella, screening of the dry-heat resistance of 108 Salmonella strains, representing 39 serotypes, identified the 22 most resistant and the 8 most sensitive strains for comparative genome analysis. A total of 289 genes of the accessory genome were differently distributed between resistant and sensitive strains. Among these genes, 28 proteins with a putative relationship to stress resistance were selected for to quantify relative gene expression before and after desiccation and expression by solid-state cultures on agar plates relative to cultures growing in liquid culture media. Of these 28 genes, 15 genes were upregulated (P < 0.05) after desiccation or by solid-state cultures on agar plates. These 15 genes were cloned into the low-copy-number vector pRK767 under the control of the lacZ promoter. The expression of 6 of these 15 genes increased (P < 0.05) resistance to dry heat and to treatment with pressure of 500 MPa. Our finding extends the knowledge of mechanisms of stress resistance in desiccated Salmonella to improve control of this bacterium in dry food. IMPORTANCE This study directly targeted an increasing threat to food safety and developed knowledge and targeted strategies that can be used by the food industry to help reduce the risk of foodborne illness in their dry products and thereby reduce the overall burden of foodborne illness. Genomic and physiological analyses have elucidated mechanisms of bacterial resistance to many food preservation technologies, including heat, pressure, disinfection chemicals, and UV light; however, information on bacterial mechanisms of resistance to dry heat is scarce. Mechanisms of tolerance to desiccation likely also contribute to resistance to dry heat, but this assumption has not been verified experimentally. It remains unclear how mechanisms of resistance to wet heat relate to dry-heat resistance. Thus, this study will fill a knowledge gap to improve the safety of dry foods.
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Wang Y, Wang J, Guo D, Zhang H, Che Y, Li Y, Tian B, Wang Z, Sun G, Zhang H. Physiological and comparative transcriptome analysis of leaf response and physiological adaption to saline alkali stress across pH values in alfalfa (Medicago sativa). PLANT PHYSIOLOGY AND BIOCHEMISTRY : PPB 2021; 167:140-152. [PMID: 34352517 DOI: 10.1016/j.plaphy.2021.07.040] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/23/2021] [Revised: 07/19/2021] [Accepted: 07/30/2021] [Indexed: 05/27/2023]
Abstract
Soil salinization is a critical factor limiting growth and causing physiological dysfunction in plants. The damage from alkaline salt in most plants is significantly greater than that from neutral salt. However, there is still a lack of research on the action mechanism by which saline alkali stress on plants under the same salt concentration across different pH values. The present study examined the effects of different pH values (7.0, 8.0, 9.0, and 10.0) under the same salt concentration (200 mmolL-1) on photosynthetic function, photoprotective mechanism, nitrogen metabolism, and osmotic regulation in alfalfa (Medicago sativa) leaves, including a transcriptomic analysis of changes in gene expression related to the above metabolic processes. The results showed that low pH saline alkali stress (pH 7.0 and 8.0) promoted chlorophyll synthesis in alfalfa leaves, and non-photochemical quenching (NPQ) and cyclic electron transfer (CEF) were promoted. There was no significant effect on plant growth or photochemical activity. The soluble sugar, proline, and soluble protein contents did not change significantly, and there was no obvious oxidative damage in alfalfa leaves. However, when pH increased to 9.0 and 10.0, KEGG enrichment analysis showed that photosynthesis (map00195) and nitrogen metabolism (map00910) were significantly enriched (P < 0.05), and PSII antenna protein coding genes were down-regulated under pH 9.0 and 10.0 treatments. The activities of PSII and PSI were decreased under high pH saline alkali stress, and the expression levels of the photosynthetic electron transporter-related genes PetA, PetB, petE, and petF were also significantly down-regulated. PSII was more sensitive to high pH saline alkali stress than PSI, and the PSII receptor side was more sensitive to high pH saline alkali stress than the PSII donor side. The activities of the oxygen-evolving complex (OEC) and PSI were significantly damaged only at pH 10.0. The activities of nitrate reductase (NR) and nitrite reductase (NiR), the expression levels of their genes, and the content of soluble protein were also decreased under pH 9.0 and 10.0 treatments. The inhibition of plant growth and oxidative damage to alfalfa leaves caused by high pH saline alkali stress were mainly related to the inhibition of photosynthesis (light energy absorption, electron transfer) and nitrogen metabolism (NO3- reduction). Under high pH saline alkali stress (pH 10.0), the photoprotection mechanisms such as CEF and NPQ were inhibited, which was also one of the important reasons for photoinhibition in alfalfa leaves. The accumulation of osmotic adjustment substances, such as soluble sugar and proline, was an important mechanism by which alfalfa physiologically adapted to high pH alkaline salt stress.
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Affiliation(s)
- Yue Wang
- College of Life Sciences, Northeast Forestry University, Harbin, Heilongjiang, China
| | - Jiechen Wang
- College of Life Sciences, Northeast Forestry University, Harbin, Heilongjiang, China
| | - Dandan Guo
- College of Life Sciences, Northeast Forestry University, Harbin, Heilongjiang, China
| | - Hongbo Zhang
- College of Life Sciences, Northeast Forestry University, Harbin, Heilongjiang, China
| | - Yanhui Che
- College of Life Sciences, Northeast Forestry University, Harbin, Heilongjiang, China
| | - Yuanyuan Li
- College of Life Sciences, Northeast Forestry University, Harbin, Heilongjiang, China
| | - Bei Tian
- College of Life Sciences, Northeast Forestry University, Harbin, Heilongjiang, China
| | - Zihan Wang
- College of Life Sciences, Northeast Forestry University, Harbin, Heilongjiang, China
| | - Guangyu Sun
- College of Life Sciences, Northeast Forestry University, Harbin, Heilongjiang, China
| | - Huihui Zhang
- College of Life Sciences, Northeast Forestry University, Harbin, Heilongjiang, China.
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Kaiwen G, Zisong X, Yuze H, Qi S, Yue W, Yanhui C, Jiechen W, Wei L, Huihui Z. Effects of salt concentration, pH, and their interaction on plant growth, nutrient uptake, and photochemistry of alfalfa ( Medicago sativa) leaves. PLANT SIGNALING & BEHAVIOR 2020; 15:1832373. [PMID: 33073686 PMCID: PMC7671061 DOI: 10.1080/15592324.2020.1832373] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/07/2023]
Abstract
In order to explore the main limiting factors affecting the growth and physiological function of alfalfa under salt and alkali stress, the effect of the salt and alkali stress on the growth and physiological function of alfalfa was studied. The results showed that effects of the excessive salt concentration (100 and 200 mM) on the growth and physiological characteristics were significantly greater than that of pH (7.0 and 9.0). Under 100 mM salt stress, there was no significant difference in the growth and photosynthetic function between pH 9.0 and pH 7.0. Under the 200 mM salt concentration the absorption of Na+ by alfalfa treated at the pH 9.0 did not increase significantly compared with absorption at the pH 7.0. However, the higher pH directly reduced the root activity, leaf's water content, and N-P-K content also decreased significantly. The PSII and PSI activities decreased with increasing the salt concentration, especially the damage degree of PSI. Although the photoinhibition of PSII was not significant, PSII donor and electron transfer from the QA to QB of the PSII receptor sides was inhibited. In a word, alfalfa showed relatively strong salt tolerance capacity, at the 100 mM salt concentration, even when the pH reached 9.0. Thus, the effect on the growth and photosynthetic function was not significant. However, at 200 mM salt concentration, pH 9.0 treatment caused damage to root system and the photosynthetic function in leaves of alfalfa was seriously injured.
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Affiliation(s)
- Guo Kaiwen
- College of Resources and Environment, Northeast Agricultural University, Harbin, Heilongjiang, China
| | - Xu Zisong
- College of Resources and Environment, Northeast Agricultural University, Harbin, Heilongjiang, China
| | - Huo Yuze
- College of Resources and Environment, Northeast Agricultural University, Harbin, Heilongjiang, China
| | - Sun Qi
- College of Resources and Environment, Northeast Agricultural University, Harbin, Heilongjiang, China
| | - Wang Yue
- Key Laboratory of Saline-alkali Vegetation Ecology Restoration, Ministry of Education, College of Life Sciences, Northeast Forestry University, Harbin, Heilongjiang, China
| | - Che Yanhui
- Key Laboratory of Saline-alkali Vegetation Ecology Restoration, Ministry of Education, College of Life Sciences, Northeast Forestry University, Harbin, Heilongjiang, China
| | - Wang Jiechen
- Key Laboratory of Saline-alkali Vegetation Ecology Restoration, Ministry of Education, College of Life Sciences, Northeast Forestry University, Harbin, Heilongjiang, China
| | - Li Wei
- College of Resources and Environment, Northeast Agricultural University, Harbin, Heilongjiang, China
| | - Zhang Huihui
- College of Resources and Environment, Northeast Agricultural University, Harbin, Heilongjiang, China
- Key Laboratory of Saline-alkali Vegetation Ecology Restoration, Ministry of Education, College of Life Sciences, Northeast Forestry University, Harbin, Heilongjiang, China
- CONTACT Zhang Huihui College of Resources and Environment, Northeast Agricultural University, Harbin, Heilongjiang, China; Li Wei
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Yanhui C, Hongrui W, Beining Z, Shixing G, Zihan W, Yue W, Huihui Z, Guangyu S. Elevated air temperature damage to photosynthetic apparatus alleviated by enhanced cyclic electron flow around photosystem I in tobacco leaves. ECOTOXICOLOGY AND ENVIRONMENTAL SAFETY 2020; 204:111136. [PMID: 32798755 DOI: 10.1016/j.ecoenv.2020.111136] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/21/2020] [Revised: 08/03/2020] [Accepted: 08/04/2020] [Indexed: 06/11/2023]
Abstract
High temperature can lead to increased production of excess light energy, thus reducing photosynthetic capacity in plants. Photosynthetic cyclic electron flow (CEF) in photosystem I (PSI) can effectively protect photosystems, but its physiological mechanism under high temperature is poorly understood. In this study, antimycin A (AA) and thenoyltrifluoroacetone (TTFA) were used to inhibit PGR5-and NDH-dependent CEF pathways, respectively, to reveal the photoprotective functions of CEF for PSII in tobacco leaves under high temperature stress (37 °C, HT). High temperatures caused decreases in maximal photochemistry efficiency (Fv/Fm) and damaged photosystem II (PSII) in tobacco leaves. Under AA inhibition of PGR5-dependent CEF, high temperature increased the fluorescence intensity of point O (Fo) in OJIP curves, i.e., the energy absorption per active reaction center (ABS/RC), the trapping rate of the reaction center (TRo/RC), and the electron transport efficiency per reaction center (ETo/RC) in tobacco leaves. High temperature induced an increase in the hydrogen peroxide content and a decrease in pigment content in tobacco leaves. Under the high temperature treatment, inhibition of PGR5-dependent CEF reduced the activities of the PSII reaction center significantly, destroyed the oxygen-evolving complex (OEC), and impeded photosynthetic electron transfer from PSII to the plastoquinone (PQ) pool in tobacco leaves. The TTFA treatment inhibited the NDH-dependent pathway under high temperature conditions, with the relative fluorescence intensity of point I (VI) decreased significantly, and the content of hydrogen peroxide and superoxide anion increased significantly. Additionally, Fo and the redox degree of the PSII donor side (Wk) increased, and pigment content decreased compared to the control, but with little change compared to high temperature treatment, indicating that the inhibition of the NDH-dependent pathway directly weakened the capacity of the PQ pool to lead to the accumulation of reactive oxygen species (ROS) in tobacco leaves. In conclusion, CEF alleviated damage to the photosynthetic apparatus in tobacco leaves by increasing PSII heat dissipation, reducing ROS production, and maintaining the stability of the PQ pool to accommodate photosynthetic electron flow.
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Affiliation(s)
- Che Yanhui
- Key Laboratory of Saline-alkali Vegetation Ecology Restoration, Ministry of Education, College of Life Sciences, Northeast Forestry University, Harbin, 150040, China
| | - Wang Hongrui
- Key Laboratory of Saline-alkali Vegetation Ecology Restoration, Ministry of Education, College of Life Sciences, Northeast Forestry University, Harbin, 150040, China
| | - Zhang Beining
- Key Laboratory of Saline-alkali Vegetation Ecology Restoration, Ministry of Education, College of Life Sciences, Northeast Forestry University, Harbin, 150040, China
| | - Gao Shixing
- Key Laboratory of Saline-alkali Vegetation Ecology Restoration, Ministry of Education, College of Life Sciences, Northeast Forestry University, Harbin, 150040, China
| | - Wang Zihan
- Key Laboratory of Saline-alkali Vegetation Ecology Restoration, Ministry of Education, College of Life Sciences, Northeast Forestry University, Harbin, 150040, China
| | - Wang Yue
- Key Laboratory of Saline-alkali Vegetation Ecology Restoration, Ministry of Education, College of Life Sciences, Northeast Forestry University, Harbin, 150040, China
| | - Zhang Huihui
- Key Laboratory of Saline-alkali Vegetation Ecology Restoration, Ministry of Education, College of Life Sciences, Northeast Forestry University, Harbin, 150040, China; College of Resources and Environment, Northeast Agricultural University, Harbin Heilongjiang, China
| | - Sun Guangyu
- Key Laboratory of Saline-alkali Vegetation Ecology Restoration, Ministry of Education, College of Life Sciences, Northeast Forestry University, Harbin, 150040, China.
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Zhang H, Huo Y, Xu Z, Guo K, Wang Y, Zhang X, Xu N, Sun G. Physiological and proteomics responses of nitrogen assimilation and glutamine/glutamine family of amino acids metabolism in mulberry ( Morus alba L.) leaves to NaCl and NaHCO 3 stress. PLANT SIGNALING & BEHAVIOR 2020; 15:1798108. [PMID: 32729371 PMCID: PMC8550533 DOI: 10.1080/15592324.2020.1798108] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/01/2020] [Revised: 06/21/2020] [Accepted: 06/22/2020] [Indexed: 05/04/2023]
Abstract
In order to find out the response mechanism of nitrogen assimilation and glutamine/glutamine family of amino acids metabolism in mulberry (Morus alba L.) leaves under NaCl and NaHCO3 stress, and to reveal its role in salt alkali adaptation. The effects of the nitrogen metabolism of mulberry leaves were studied under 100 mmol L-1 NaCl and NaHCO3 stress.The results showed that the activity of NR and the content of TN and SP did not change significantly, the expression of NiR, Fd-NiR, Fd-NiR gene and theactivity of NiR increased significantly under NaCl stress, but nitrogen assimilation was inhibited under NaHCO3 stress. NaCl stress had no significant effect on the expression and activity of GS and GOGAT in mulberry leaves. Under NaHCO3 stress, the expression of Fd-GOGAT, Fd-GOGAT2, Fd-GOGAT gene, and the activity of GS and GOGAT were significantly decreased. NaCl stress can promote the accumulation of Pro, Put and Spd in mulberry leaves. The accumulation of Pro under NaHCO3 stress is greater than that under NaCl stress. NaCl stress also induced the up-regulation of GAD, GAD1 and GAD1 gene expression, so promoting the synthesis of GABA may be an adaptive mechanism for mulberry to cope with NaCl stress, but the expression of GAD did not change significantly and GAD gene expression lower than CK under NaHCO3 stress. Although both NaCl and NaHCO3 stress could promote the synthesis of GSH by up-regulation of GCLM expression, GSH under NaHCO3 stress was significantly higher than that under NaCl stress, the content of H2O2 was still significantly higher than that of NaCl stress, that means GSH may not play a key role in alleviating the oxidative damage in mulberry leaves caused by salt and alkali.
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Affiliation(s)
- Huihui Zhang
- College of Resources and Environment, NortheastAgriculturalUniversity, Harbin, Heilongjiang, China
- Key Laboratory of Saline-alkali Vegetation Ecology Restoration, Ministry of Education, Northeast Forestry University, Harbin, Heilongjiang, China
| | - Yuze Huo
- College of Resources and Environment, NortheastAgriculturalUniversity, Harbin, Heilongjiang, China
| | - Zisong Xu
- College of Resources and Environment, NortheastAgriculturalUniversity, Harbin, Heilongjiang, China
| | - Kaiwen Guo
- College of Resources and Environment, NortheastAgriculturalUniversity, Harbin, Heilongjiang, China
| | - Yue Wang
- Key Laboratory of Saline-alkali Vegetation Ecology Restoration, Ministry of Education, Northeast Forestry University, Harbin, Heilongjiang, China
| | - Xiaosong Zhang
- Department of Research and Education, Dalian Academy of Agricultural Sciences, Dalian, Liaoning, China
| | - Nan Xu
- Key Laboratory of Saline-alkali Vegetation Ecology Restoration, Ministry of Education, Northeast Forestry University, Harbin, Heilongjiang, China
- Province Key Laboratory of Cold Region Wetland Ecology and Environment Research, Harbin University, Harbin, Heilongjiang, China
- Natural Resources and Ecology Institute, Heilongjiang Sciences Academy, Harbin, Heilongjiang, China
| | - Guangyu Sun
- Key Laboratory of Saline-alkali Vegetation Ecology Restoration, Ministry of Education, Northeast Forestry University, Harbin, Heilongjiang, China
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Zhang H, Xu Z, Guo K, Huo Y, He G, Sun H, Guan Y, Xu N, Yang W, Sun G. Toxic effects of heavy metal Cd and Zn on chlorophyll, carotenoid metabolism and photosynthetic function in tobacco leaves revealed by physiological and proteomics analysis. ECOTOXICOLOGY AND ENVIRONMENTAL SAFETY 2020; 202:110856. [PMID: 32629202 DOI: 10.1016/j.ecoenv.2020.110856] [Citation(s) in RCA: 79] [Impact Index Per Article: 19.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/30/2020] [Revised: 05/29/2020] [Accepted: 06/01/2020] [Indexed: 05/18/2023]
Abstract
To explore the mechanisms underlying the action of the heavy metals Cd and Zn on the photosynthetic function of plant leaves, the effects of 100 μmol L-1 Cd and 200 μmol L-1 Zn stress (the exposure concentrations of Cd and Zn in the culture medium were 2.24 mg kg-1 and 5.36 mg kg-1) on the chlorophyll and carotenoid contents as well as the photosynthetic function of tobacco leaves (Long Jiang 911) were studied. The key proteins in these physiological processes were quantitatively analyzed using a TMT-based proteomics approach. Cd stress was found to inhibit the expression of key enzymes during chlorophyll synthesis in leaves, resulting in a decrease of the Chl content. However, Zn stress did not significantly influence the chlorophyll content. Leaves adapted to Zn stress by upregulating CAO expression and increase the Chl b content. Although the Car content in leaves did not significantly change under either Cd or Zn stress, the expressions of ZE and VDE during Car metabolism decreased significantly under Cd stress. This was accompanied by damages to the xanthophyll cycle and the NPQ-dependent energy dissipation mechanism. In contrast, under Zn stress, leaves adapted to Zn stress by increasing the expression of VDE, thus improving NPQ. Under Cd stress, the expressions of three sets of proteins were significantly down-regulated, including PSII donor-side proteins (PPD3, PPD6, OEE1, OEE2-1, OEE2-2, OEE2-3, and OEE3-2), receptor-side proteins (D1, D2, CP43, CP47, Cyt b559α, Cyt b559β, PsbL, PsbQ, PsbR, Psb27-H1, and Psb28), and core proteins of the PSI reaction center (psaA, psaB, psaC, psaD, psaE-A, PsaE-B, psaF, psaG, psaH-1, psaK, psaL, psaN, and psaOL). In comparison, only eight of the above proteins (PPD6, OEE3-2, PsbL, PsbQ, Psb27-H1, psaL, and psaOL) were significantly down-regulated by Zn stress. Under Cd stress, both the donor side and the receptor side of PSII were damaged, and PSII and PSI experienced severe photoinhibition. However, Zn stress did not decrease either PSII or PSI activities in tobacco leaves. In addition, the expression of electron transport-related proteins (cytb6/f complex, PC, Fd, and FNR), ATPase subunits, Rubisco subunits, and RCA decreased significantly in leaves under Cd stress. However, no significant changes were observed in any of these proteins under Zn stress. Although Cd stress was found to up-regulate the expressions of PGRL1A and PGRL1B and induce an increase of PGR5/PGRL1-CEF in tobacco leaves, NDH-CEF was significantly inhibited. Under Zn stress, the expressions of ndhH and PGRL1A in leaves were significantly up-regulated, but there were no significant changes in either NDH-CEF or PGR5/PGRL-CEF. Under Cd stress, the expressions of proteins related to Fd-dependent nitrogen metabolism and reactive oxygen species (ROS) scavenging processes (e.g., FTR, Fd-NiR, and Fd-GOGAT) were significantly down-regulated in leaves. However, no significant changes of any of the above proteins were identified under Zn stress. In summary, Cd stress could inhibit the synthesis of chlorophyll in tobacco leaves, significantly down-regulate the expressions of photosynthesis-related proteins or subunits, and suppress both the xanthophyll cycle and NDH-CEF process. The expressions of proteins related to the Fd-dependent nitrogen metabolism and ROS scavenging were also significantly down-regulated, which blocked the photosynthetic electron transport, thus resulting in severe photoinhibition of both PSII and PSI. However, Zn stress had little effect on the photosynthetic function of tobacco leaves.
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Affiliation(s)
- Huihui Zhang
- College of Resources and Environment, Northeast Agricultural University, Harbin, Heilongjiang, China; Key Laboratory of Saline-alkali Vegetation Ecology Restoration, Ministry of Education, College of Life Sciences, Northeast Forestry University, Harbin, Heilongjiang, China
| | - Zisong Xu
- College of Resources and Environment, Northeast Agricultural University, Harbin, Heilongjiang, China
| | - Kaiwen Guo
- College of Resources and Environment, Northeast Agricultural University, Harbin, Heilongjiang, China
| | - Yuze Huo
- College of Resources and Environment, Northeast Agricultural University, Harbin, Heilongjiang, China
| | - Guoqiang He
- Mudanjiang Tobacco Science Research Institute, Mudanjiang, Heilongjiang, China
| | - Hongwei Sun
- Mudanjiang Tobacco Science Research Institute, Mudanjiang, Heilongjiang, China
| | - Yupeng Guan
- College of Resources and Environment, Northeast Agricultural University, Harbin, Heilongjiang, China
| | - Nan Xu
- Natural Resources and Ecology Institute, Heilongjiang Sciences Academy, Harbin, Heilongjiang, China
| | - Wei Yang
- College of Resources and Environment, Northeast Agricultural University, Harbin, Heilongjiang, China.
| | - Guangyu Sun
- Key Laboratory of Saline-alkali Vegetation Ecology Restoration, Ministry of Education, College of Life Sciences, Northeast Forestry University, Harbin, Heilongjiang, China.
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Huihui Z, Xin L, Zisong X, Yue W, Zhiyuan T, Meijun A, Yuehui Z, Wenxu Z, Nan X, Guangyu S. Toxic effects of heavy metals Pb and Cd on mulberry (Morus alba L.) seedling leaves: Photosynthetic function and reactive oxygen species (ROS) metabolism responses. ECOTOXICOLOGY AND ENVIRONMENTAL SAFETY 2020; 195:110469. [PMID: 32179235 DOI: 10.1016/j.ecoenv.2020.110469] [Citation(s) in RCA: 79] [Impact Index Per Article: 19.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/14/2020] [Revised: 03/06/2020] [Accepted: 03/09/2020] [Indexed: 05/03/2023]
Abstract
To explore the mechanism of how lead (Pb) and cadmium (Cd) stress affects photosynthesis of mulberry (Morus alba L.), we looked at the effects of different concentrations of Pb and Cd stress (at 100 and 200 μmol L-1), which are two heavy metal elements, on leaf chlorophyll (Chl), photosynthesis gas exchange, Chl fluorescence, and reactive oxygen species (ROS) metabolism in mulberry leaves. The results showed that higher concentrations of Pb and Cd reduced leaf Chl content, especially in Chl a where content was more sensitive than in Chl b. Under Pb and Cd stress, the photosynthetic carbon assimilation capacity of mulberry leaves was reduced, which was a consequence of combined limitations of stomatal and non-stomatal factors. The main non-stomatal factors were decreased photosystem II (PSII) and photosystem I (PSI) activity and carboxylation efficiency (CE). Damage to the donor side of the PSII reaction center was greater than the acceptor side. After being treated with 100 μmol L-1 of Pb and Cd, mulberry leaves continued to be able to dissipate excess excitation energy by starting non-photochemical quenching (NPQ), but when Pb and Cd concentrations were increased to 200 μmol L-1, the protection mechanism that depends on NPQ was impaired. Excessive excitation energy from chloroplasts promoted a great increase of ROS, such as superoxide anion (O2•-) and H2O2. Moreover, under high Pb and Cd stress, superoxide dismutase (SOD) and ascorbate peroxidase (APX) were also inhibited to some extent, and excessive ROS also resulted in a significantly higher degree of oxidative damage. Compared with Cd, the effect of Pb stress at the same concentration level displayed a significantly lower impact on Chl content, photosynthetic carbon assimilation, and stomatal conductance. Meanwhile, Pb stress mainly damaged activity of the oxygen-evolving complex (OEC) located on PSII donor side, but it reduced the electronic pressure on the PSII acceptor side and PSI. Furthermore, under Pb stress, the NPQ, SOD, and APX activity were all significantly higher than those under Cd stress. Thus under Pb stress, the degree of photoinhibition and oxidative damage of PSII and PSI in mulberry leaves were significantly lower than under Cd stress.
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Affiliation(s)
- Zhang Huihui
- College of Resources and Environment, Northeast Agricultural University, Harbin, Heilongjiang, China; Key Laboratory of Saline-alkali Vegetation Ecology Restoration, Ministry of Education, College of Life Sciences, Northeast Forestry University, Harbin, Heilongjiang, China
| | - Li Xin
- College of Resources and Environment, Northeast Agricultural University, Harbin, Heilongjiang, China; Key Laboratory of Saline-alkali Vegetation Ecology Restoration, Ministry of Education, College of Life Sciences, Northeast Forestry University, Harbin, Heilongjiang, China
| | - Xu Zisong
- College of Resources and Environment, Northeast Agricultural University, Harbin, Heilongjiang, China
| | - Wang Yue
- Key Laboratory of Saline-alkali Vegetation Ecology Restoration, Ministry of Education, College of Life Sciences, Northeast Forestry University, Harbin, Heilongjiang, China
| | - Teng Zhiyuan
- Key Laboratory of Saline-alkali Vegetation Ecology Restoration, Ministry of Education, College of Life Sciences, Northeast Forestry University, Harbin, Heilongjiang, China
| | - An Meijun
- Developmental Center of Heilongjiang Provincial Sericulture and Bee Industry, Harbin, Heilongjiang, China
| | - Zhang Yuehui
- Developmental Center of Heilongjiang Provincial Sericulture and Bee Industry, Harbin, Heilongjiang, China
| | - Zhu Wenxu
- School of Forestry, Shenyang Agricultural University, Shenyang, Liaoning, China
| | - Xu Nan
- Key Laboratory of Saline-alkali Vegetation Ecology Restoration, Ministry of Education, College of Life Sciences, Northeast Forestry University, Harbin, Heilongjiang, China; Natural Resources and Ecology Institute, Heilongjiang Sciences Academy, Harbin, Heilongjiang, China.
| | - Sun Guangyu
- Key Laboratory of Saline-alkali Vegetation Ecology Restoration, Ministry of Education, College of Life Sciences, Northeast Forestry University, Harbin, Heilongjiang, China.
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