Antioxidants

Research

21 pages, 6823 KiB

Open AccessArticle

Effect of Thallium(I) on Growth, Nutrient Absorption, Photosynthetic Pigments, and Antioxidant Response of Dittrichia Plants

by Francisco Espinosa, Alfonso Ortega, Francisco L. Espinosa-Vellarino and Inmaculada Garrido

Antioxidants 2023, 12(3), 678; https://doi.org/10.3390/antiox12030678 - 09 Mar 2023

Cited by 6 | Viewed by 2218

Abstract

Dittrichia plants were exposed to thallium (Tl) stress (10, 50, and 100 µM) for 7 days. The Tl toxicity altered the absorption and accumulation of other nutrients. In both the roots and the leaves, there was a decline in K, Mg, and Fe [...] Read more.

Dittrichia plants were exposed to thallium (Tl) stress (10, 50, and 100 µM) for 7 days. The Tl toxicity altered the absorption and accumulation of other nutrients. In both the roots and the leaves, there was a decline in K, Mg, and Fe content, but an increase in Ca, Mn, and Zn. Chlorophylls decreased, as did the photosynthetic efficiency, while carotenoids increased. Oxidative stress in the roots was reflected in increased lipid peroxidation. There was more production of superoxide (O₂^.−), hydrogen peroxide (H₂O₂), and nitric oxide (NO) in the roots than in the leaves, with increases in both organs in response to Tl toxicity, except for O₂^.− production in the roots, which fluctuated. There was increased hydrogen sulfide (H₂S) production, especially in the leaves. Superoxide dismutase (SOD), ascorbate peroxidase (APX), dehydroascorbate reductase (DHAR), monodehydroascorbate reductase (MDHAR), and glutathione reductase (GR) showed increased activities, except for APX and MDHAR in the roots and GR in the leaves. The components of the ascorbate–glutathione cycle were affected. Thus, ascorbate (AsA) increased, while dehydroascorbate (DHA), reduced glutathione (GSH), and oxidized glutathione (GSSG) decreased, except for in the roots at 100 µM Tl, which showed increased GSH. These Tl toxicity-induced alterations modify the AsA/DHA and GSH/GSSG redox status. The NO and H₂S interaction may act by activating the antioxidant system. The effects of Tl could be related to its strong affinity for binding with -SH groups, thus altering the functionality of proteins and the cellular redox state. Full article

(This article belongs to the Special Issue Plant Response and Tolerance to Abiotic Oxidative Stress: Antioxidant Machinery as a Paradigm of Defense)

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24 pages, 3841 KiB

Open AccessArticle

Genome-Wide Identification and Characterization of the Polyamine Uptake Transporter (Put) Gene Family in Tomatoes and the Role of Put2 in Response to Salt Stress

by Min Zhong, Lingqi Yue, Wei Liu, Hongyi Qin, Bingfu Lei, Riming Huang, Xian Yang and Yunyan Kang

Antioxidants 2023, 12(2), 228; https://doi.org/10.3390/antiox12020228 - 18 Jan 2023

Cited by 5 | Viewed by 1814

Abstract

The polyamine uptake transporter (Put), an important polyamines-related protein, is involved in plant cell growth, developmental processes, and abiotic stimuli, but no research on the Put family has been carried out in the tomato. Herein, eight tomato Put were identified and scattered across [...] Read more.

The polyamine uptake transporter (Put), an important polyamines-related protein, is involved in plant cell growth, developmental processes, and abiotic stimuli, but no research on the Put family has been carried out in the tomato. Herein, eight tomato Put were identified and scattered across four chromosomes, which were classified into three primary groups by phylogenetic analysis. Protein domains and gene structural organization also showed a significant degree of similarity, and the Put genes were significantly induced by various hormones and polyamines. Tissue-specific expression analysis indicated that Put genes were expressed in all tissues of the tomato. The majority of Put genes were induced by different abiotic stresses. Furthermore, Put2 transcription was found to be responsive to salt stress, and overexpression of Put2 in yeast conferred salinity tolerance and polyamine uptake. Moreover, overexpression of Put2 in tomatoes promoted salinity tolerance accompanied by a decrease in the Na⁺/K⁺ ratio, restricting the generation of reactive oxygen and increasing polyamine metabolism and catabolism, antioxidant enzyme activity (SOD, CAT, APX, and POD), and nonenzymatic antioxidant activity (GSH/GSSG and ASA/DHA ratios, GABA, and flavonoid content); loss of function of put2 produced opposite effects. These findings highlight that Put2 plays a pivotal role in mediating polyamine synthesis and catabolism, and the antioxidant capacity in tomatoes, providing a valuable gene for salinity tolerance in plants. Full article

(This article belongs to the Special Issue Plant Response and Tolerance to Abiotic Oxidative Stress: Antioxidant Machinery as a Paradigm of Defense)

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18 pages, 8153 KiB

Open AccessArticle

Leucine Contributes to Copper Stress Tolerance in Peach (Prunus persica) Seedlings by Enhancing Photosynthesis and the Antioxidant Defense System

by Maoxiang Sun, Suhong Li, Qingtao Gong, Yuansong Xiao and Futian Peng

Antioxidants 2022, 11(12), 2455; https://doi.org/10.3390/antiox11122455 - 13 Dec 2022

Cited by 6 | Viewed by 1501

Abstract

Heavy metal contamination has a severe impact on ecological health and plant growth and is becoming increasingly serious globally. Copper (Cu) is a heavy metal that is essential for the growth and development of plants, including peach (Prunus persica L. Batsch); however, [...] Read more.

Heavy metal contamination has a severe impact on ecological health and plant growth and is becoming increasingly serious globally. Copper (Cu) is a heavy metal that is essential for the growth and development of plants, including peach (Prunus persica L. Batsch); however, an excess is toxic. In plants, amino acids are involved in responses to abiotic and biotic stresses, such as water deficit, extreme temperatures, high salinity, and heavy metal stress. However, the role of leucine in the regulation of heavy metal stress is currently unclear. Therefore, we investigated the effects of exogenous leucine on the growth of peach seedlings under Cu stress. Exogenous leucine improved the leaf ultrastructure and ionic balance and increased the chlorophyll content, the net photosynthetic rate, and the maximum photochemical efficiency. Furthermore, it attenuated Cu-stress-induced oxidative damage via a decrease in reactive oxygen species (ROS) and the regulation of the antioxidant and osmotic systems. These effects, in turn, ameliorated the reductions in cell viability, cellular activity, and biomass under Cu stress. Moreover, exogenous leucine increased the activities of nitrate reductase (NR), glutamine synthetase (GS), and glutamic acid synthetase (GOGAT) and thus improved the nitrogen metabolism efficiency of plants. In conclusion, leucine significantly improved the photosynthetic performance and antioxidant capacity, reduced Cu accumulation, and promoted nitrogen metabolism, which in turn improved the resistance of peach seedlings to Cu stress. Full article

(This article belongs to the Special Issue Plant Response and Tolerance to Abiotic Oxidative Stress: Antioxidant Machinery as a Paradigm of Defense)

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20 pages, 6102 KiB

Open AccessArticle

Vanadium Stress Alters Sweet Potato (Ipomoea batatas L.) Growth, ROS Accumulation, Antioxidant Defense System, Stomatal Traits, and Vanadium Uptake

by Sunjeet Kumar, Mengzhao Wang, Yonghua Liu, Zhixin Zhu, Shah Fahad, Abdul Qayyum and Guopeng Zhu

Antioxidants 2022, 11(12), 2407; https://doi.org/10.3390/antiox11122407 - 05 Dec 2022

Cited by 5 | Viewed by 1632

Abstract

Vanadium (V) is a heavy metal found in trace amounts in many plants and widely distributed in the soil. This study investigated the effects of vanadium concentrations on sweet potato growth, biomass, root morphology, photosynthesis, photosynthetic assimilation, antioxidant defense system, stomatal traits, and [...] Read more.

Vanadium (V) is a heavy metal found in trace amounts in many plants and widely distributed in the soil. This study investigated the effects of vanadium concentrations on sweet potato growth, biomass, root morphology, photosynthesis, photosynthetic assimilation, antioxidant defense system, stomatal traits, and V accumulation. Sweet potato plants were grown hydroponically and treated with five levels of V (0, 10, 25, 50, and 75 mg L⁻¹). After 7 days of treatment, V content at low concentration (10 mg L⁻¹) enhanced the plant growth and biomass; in contrast, drastic effects were observed at 25, 50, and 75 mg L⁻¹. Higher V concentrations negatively affect the relative water content, photosynthetic assimilation, photosynthesis, and root growth and reduce tolerance indices. The stomatal traits of sweet potato, such as stomatal length, width, pore length, and pore width, were also decreased under higher V application. Furthermore, V concentration and uptake in the roots were higher than in the shoots. In the same way, reactive oxygen species (ROS) production (hydrogen peroxide), lipid peroxidation (malondialdehyde), osmolytes, glutathione, and enzymes (catalase and superoxide dismutase) activities were increased significantly under V stress. In conclusion, V at a low level (10 mg L⁻¹) enhanced sweet potato growth, and a higher level of V treatment (25, 50, and 75 mg L⁻¹) had a deleterious impact on the growth, physiology, and biochemical mechanisms, as well as stomatal traits of sweet potato. Full article

(This article belongs to the Special Issue Plant Response and Tolerance to Abiotic Oxidative Stress: Antioxidant Machinery as a Paradigm of Defense)

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18 pages, 3887 KiB

Open AccessArticle

Transcriptome and Metabolome Analysis Revealed That Exogenous Spermidine-Modulated Flavone Enhances the Heat Tolerance of Lettuce

by Wenjing Sun, Jinghong Hao, Shuangxi Fan, Chaojie Liu and Yingyan Han

Antioxidants 2022, 11(12), 2332; https://doi.org/10.3390/antiox11122332 - 25 Nov 2022

Cited by 3 | Viewed by 1639

Abstract

Lettuce is sensitive to high temperature, and exogenous spermidine can improve heat tolerance in lettuce, but its intrinsic mechanism is still unclear. We analyzed the effects of exogenous spermidine on the leaf physiological metabolism, transcriptome and metabolome of lettuce seedlings under high-temperature stress [...] Read more.

Lettuce is sensitive to high temperature, and exogenous spermidine can improve heat tolerance in lettuce, but its intrinsic mechanism is still unclear. We analyzed the effects of exogenous spermidine on the leaf physiological metabolism, transcriptome and metabolome of lettuce seedlings under high-temperature stress using the heat-sensitive lettuce variety ‘Beisansheng No. 3′ as the material. The results showed that exogenous spermidine increased the total fresh weight, total dry weight, root length, chlorophyll content and total flavonoid content, increased the activities of antioxidant enzymes such as superoxide dismutase (SOD), peroxidase (POD) and catalase (CAT), and decreased malondialdehyde (MDA) content in lettuce under high temperature stress. Transcriptome and metabolome analyses revealed 818 differentially expressed genes (DEGs) and 393 metabolites between water spray and spermidine spray treatments under high temperature stress, and 75 genes from 13 transcription factors (TF) families were included in the DEGs. The Kyoto encyclopedia of genes and genomes (KEGG) pathway enrichment analysis of DEG contains pathways for plant–pathogen interactions, photosynthesis-antennal proteins, mitogen-activated protein kinase (MAPK) signaling pathway and flavonoid biosynthesis. A total of 19 genes related to flavonoid synthesis were detected. Most of these 19 DEGs were down-regulated under high temperature stress and up-regulated after spermidine application, which may be responsible for the increase in total flavonoid content. We provide a possible source and conjecture for exploring the mechanism of exogenous spermidine-mediated heat tolerance in lettuce. Full article

(This article belongs to the Special Issue Plant Response and Tolerance to Abiotic Oxidative Stress: Antioxidant Machinery as a Paradigm of Defense)

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22 pages, 22448 KiB

Open AccessArticle

Morpho-Physiological and Biochemical Responses of Hydroponically Grown Basil Cultivars to Salt Stress

by Michele Ciriello, Luigi Formisano, Marios C. Kyriacou, Petronia Carillo, Luca Scognamiglio, Stefania De Pascale and Youssef Rouphael

Antioxidants 2022, 11(11), 2207; https://doi.org/10.3390/antiox11112207 - 08 Nov 2022

Cited by 3 | Viewed by 1459

Abstract

Depending on duration and magnitude, abiotic stresses interfere with plant metabolic processes and may severely impact developmental and qualitative attributes. In this study, in addition to characterizing three different cultivars of basil (‘Anise’, ‘Cinnamon’, and ‘Lemon’) grown under hydroponics, we appraised the impact [...] Read more.

Depending on duration and magnitude, abiotic stresses interfere with plant metabolic processes and may severely impact developmental and qualitative attributes. In this study, in addition to characterizing three different cultivars of basil (‘Anise’, ‘Cinnamon’, and ‘Lemon’) grown under hydroponics, we appraised the impact of NaCl salt stress (60 mM) on morphophysiological and nutraceutical properties of the basil crop. Salt stress significantly reduced fresh yield (51.54%, on average) and photosynthetic parameters (ACO₂, E, and gs) in all cultivars by raising tissue concentrations of Na⁺ and Cl⁻. In addition to reducing the concentration of nitrate (77.21%), NaCl salt stress increased the concentrations of key bioactive molecules, notably carotenoids (lutein and β-carotene), phenolic acids, and flavonoid derivatives, thus resulting in a higher antioxidant activity of salt-treated basil plants compared to the untreated ones. Analysis by UHPLC revealed that cichoric acid was the most abundant polyphenolic compound in all basil cultivars, with the highest values recorded in ‘Cinnamon’. Full article

(This article belongs to the Special Issue Plant Response and Tolerance to Abiotic Oxidative Stress: Antioxidant Machinery as a Paradigm of Defense)

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19 pages, 3200 KiB

Open AccessArticle

Salt Stress Induces Changes in Physiological Characteristics, Bioactive Constituents, and Antioxidants in Kenaf (Hibiscus cannabinus L.)

by Ziggiju Mesenbet Birhanie, Dawei Yang, Mingbao Luan, Aiping Xiao, Liangliang Liu, Chao Zhang, Ashok Biswas, Susmita Dey, Yong Deng and Defang Li

Antioxidants 2022, 11(10), 2005; https://doi.org/10.3390/antiox11102005 - 10 Oct 2022

Cited by 9 | Viewed by 2521

Abstract

Salinity stress is a major environmental threat in agricultural systems. Kenaf is a promising crop for the future for cultivation in salinity-affected soils because of its high phytoremediation potential. The current study aimed to investigate the effects of salt stress using six different [...] Read more.

Salinity stress is a major environmental threat in agricultural systems. Kenaf is a promising crop for the future for cultivation in salinity-affected soils because of its high phytoremediation potential. The current study aimed to investigate the effects of salt stress using six different sodium chloride (NaCl) concentrations (0, 50, 100, 150, 200, and 250 mM) on the plant growth, physiological characteristics, bioactive constituents, and antioxidant capacity of H. cannabinus. The results indicated that the NaCl stress induced significant reductions in plant height and in the dry and fresh weights of the leaf tissue. In addition, the K, Ca, Mg, and P concentrations in this tissue also decreased under NaCl stress treatment conditions. In contrast, the NaCl stress led to the accumulation of hydrogen peroxide (H₂O₂), superoxide anion (O₂^•−), malondialdehyde (MDA), proline, total soluble sugar, and total soluble protein. Under NaCl stress, the levels of antioxidants, including phenolics and flavonoids, also increased. The gas chromatography–mass spectrometry (GC-MS) results showed that the volatile compounds, including heptacosane, 1-octadecanesulphonyl chloride, and tetratetracontane, were induced under the NaCl stress treatment. Furthermore, the salt stress significantly improved the antioxidant capacity of the leaf extracts. These findings may provide insight into how H. cannabinus plants respond to salt stress and may help improve its medicinal value under salt stress. Full article

(This article belongs to the Special Issue Plant Response and Tolerance to Abiotic Oxidative Stress: Antioxidant Machinery as a Paradigm of Defense)

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19 pages, 2822 KiB

Open AccessArticle

Exogenous Betaine Enhances the Protrusion Vigor of Rice Seeds under Heat Stress by Regulating Plant Hormone Signal Transduction and Its Interaction Network

by Xu Mo, Jingya Qian, Peng Liu, Hongli Zeng, Guanghui Chen and Yue Wang

Antioxidants 2022, 11(9), 1792; https://doi.org/10.3390/antiox11091792 - 11 Sep 2022

Cited by 4 | Viewed by 1835

Abstract

Rice is an important food crop. Rice seedlings are mainly composed of root, coleoptile, mesocotyl and euphylla. The elongation of coleoptile and mesocotyl promotes the emergence of rice seedlings. Therefore, analyzing the mechanism of coleoptile and mesocotyl elongation is important for the cultivation [...] Read more.

Rice is an important food crop. Rice seedlings are mainly composed of root, coleoptile, mesocotyl and euphylla. The elongation of coleoptile and mesocotyl promotes the emergence of rice seedlings. Therefore, analyzing the mechanism of coleoptile and mesocotyl elongation is important for the cultivation of rice varieties. Due to global warming, heat stress is threatening rice yields. Betaine plays an important role in plant resistance to heat stress; however, we lack research on its regulation mechanism of rice seed germination under heat stress. Therefore, we explored the effects of soaking seeds with betaine at different concentrations on rice seed germination under heat stress. According to the results, soaking seeds with 10 mM of betaine could effectively improve the seeds’ germination potential and rate under heat stress to promote the germination of rice seeds. To clarify the mitigation mechanism of betaine in heat stress, we measured the antioxidant enzyme activity, malondialdehyde content, soluble protein content and endogenous hormone content of seed protrusion under heat stress. We constructed the cDNA library for transcriptome sequencing. According to the results, 10 mM of betaine improved the activities of the superoxide dismutase, peroxidase and catalase of seed protrusion under heat stress to reduce the malondialdehyde content and increase the soluble protein content to alleviate the effect of heat stress on rice seed germination. The detection of the endogenous hormone content showed that soaking seeds with 10 mM of betaine increased the content of gibberellin and decreased the contents of auxin and abscisic acid of seed protrusion under heat stress. According to the transcriptome analysis, betaine can induce the expressions of key genes in the biosynthesis and metabolism of auxin, abscisic acid and gibberellins in the seed coleoptile and mesocotyl elongation stage, regulate the signal transduction of three hormones and promote the germination of rice seeds under heat stress. This study revealed, for the first time, the physiological and molecular regulation mechanism of betaine promotion of seed germination under heat stress. Full article

(This article belongs to the Special Issue Plant Response and Tolerance to Abiotic Oxidative Stress: Antioxidant Machinery as a Paradigm of Defense)

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21 pages, 5672 KiB

Open AccessArticle

Genome-Wide Identification and Characterization of Chinese Cabbage S1fa Transcription Factors and Their Roles in Response to Salt Stress

by Ali Anwar, Shu Zhang, Li-Xia Wang, Fengde Wang, Lilong He and Jianwei Gao

Antioxidants 2022, 11(9), 1782; https://doi.org/10.3390/antiox11091782 - 09 Sep 2022

Cited by 3 | Viewed by 1671

Abstract

The S1fa transcription factor is part of a small family involved in plant growth and development and abiotic stress tolerance. However, the roles of the S1fa genes in abiotic stress tolerance in Chinese cabbage are still unclear. In this study, four S1fa genes [...] Read more.

The S1fa transcription factor is part of a small family involved in plant growth and development and abiotic stress tolerance. However, the roles of the S1fa genes in abiotic stress tolerance in Chinese cabbage are still unclear. In this study, four S1fa genes in the Chinese cabbage genome were identified and characterized for abiotic stress tolerance. Tissue-specific expression analysis suggested that three of these four S1fa genes were expressed in all tissues of Chinese cabbage, while Bra006994 was only expressed in the silique. Under Hg and Cd stresses, the S1fa genes were significantly expressed but were downregulated under NaCl stresses. The Bra034084 and Bra029784 overexpressing yeast cells exhibited high sensitivity to NaCl stresses, which led to slower growth compared with the wild type yeast cells (EV) under 1 M NaCl stress. In addition, the growth curve of the Bra034084 and Bra029784 overexpressing cells shows that the optical density was reduced significantly under salt stresses. The activities of the antioxidant enzymes, SOD, POD and CAT, were decreased, and the MDA, H₂O₂ and O₂⁻ contents were increased under salt stresses. The expression levels of cell wall biosynthesis genes Ccw14p, Cha1p, Cwp2p, Sed1p, Rlm1p, Rom2p, Mkk1p, Hsp12p, Mkk2p, Sdp1p and YLR194c were significantly enhanced, while Bck1p, and Ptc1p were downregulated under salt stresses. These results suggest that the Bra034084 and Bra029784 genes regulate cell wall biosynthesis and the defense regulatory system under salt stresses. These findings provide a fundamental basis for the further investigation of crop genetic modification to improve crop production and abiotic stress tolerance in Chinese cabbage. Full article

(This article belongs to the Special Issue Plant Response and Tolerance to Abiotic Oxidative Stress: Antioxidant Machinery as a Paradigm of Defense)

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20 pages, 3946 KiB

Open AccessArticle

Seed Priming with Spermine Mitigates Chromium Stress in Rice by Modifying the Ion Homeostasis, Cellular Ultrastructure and Phytohormones Balance

by Farwa Basit, Javaid Akhter Bhat, Zaid Ulhassan, Muhammad Noman, Biying Zhao, Weijun Zhou, Prashant Kaushik, Ajaz Ahmad, Parvaiz Ahmad and Yajing Guan

Antioxidants 2022, 11(9), 1704; https://doi.org/10.3390/antiox11091704 - 30 Aug 2022

Cited by 11 | Viewed by 1890

Abstract

Chromium (Cr) is an important environmental constraint effecting crop productivity. Spermine (SPM) is a polyamine compound regulating plant responses to abiotic stresses. However, SPM-mediated tolerance mechanisms against Cr stress are less commonly explored in plants. Thus, current research was conducted to explore the [...] Read more.

Chromium (Cr) is an important environmental constraint effecting crop productivity. Spermine (SPM) is a polyamine compound regulating plant responses to abiotic stresses. However, SPM-mediated tolerance mechanisms against Cr stress are less commonly explored in plants. Thus, current research was conducted to explore the protective mechanisms of SPM (0.01 mM) against Cr (100 µM) toxicity in two rice cultivars, CY927 (sensitive) and YLY689 (tolerant) at the seedling stage. Our results revealed that, alone, Cr exposure significantly reduced seed germination, biomass and photosynthetic related parameters, caused nutrient and hormonal imbalance, desynchronized antioxidant enzymes, and triggered oxidative damage by over-accretion of reactive oxygen species (ROS), malondialdehyde (MDA) and electrolyte leakage in both rice varieties, with greater impairments in CY927 than YLY689. However, seed priming with SPM notably improved or reversed the above-mentioned parameters, especially in YLY689. Besides, SPM stimulated the stress-responsive genes of endogenous phytohormones, especially salicylic acid (SA), as confirmed by the pronounced transcript levels of SA-related genes (OsPR1, OsPR2 and OsNPR1). Our findings specified that SPM enhanced rice tolerance against Cr toxicity via decreasing accumulation of Cr and markers of oxidative damage (H₂O₂, O₂^•− and MDA), improving antioxidant defense enzymes, photosynthetic apparatus, nutrients and phytohormone balance. Full article

(This article belongs to the Special Issue Plant Response and Tolerance to Abiotic Oxidative Stress: Antioxidant Machinery as a Paradigm of Defense)

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16 pages, 1757 KiB

Open AccessArticle

Role of Plasma Membrane NADPH Oxidase in Response to Salt Stress in Cucumber Seedlings

by Katarzyna Kabała, Małgorzata Reda, Anna Wdowikowska and Małgorzata Janicka

Antioxidants 2022, 11(8), 1534; https://doi.org/10.3390/antiox11081534 - 06 Aug 2022

Cited by 12 | Viewed by 1867

Abstract

Plasma membrane NADPH oxidases (RBOHs, EC 1.6.3.1) are known as the main ROS generators involved in plant adaptation to stress conditions. In the present work, regulation of NADPH oxidase was analyzed in cucumber (Cucumis sativus L. var. Krak) seedlings exposed to salinity. [...] Read more.

Plasma membrane NADPH oxidases (RBOHs, EC 1.6.3.1) are known as the main ROS generators involved in plant adaptation to stress conditions. In the present work, regulation of NADPH oxidase was analyzed in cucumber (Cucumis sativus L. var. Krak) seedlings exposed to salinity. RBOH activity and gene expression, as well as H₂O₂ content, were determined in the roots of plants treated with 50 or 100 mM NaCl for 1 h, and 50 mM NaCl for 1 or 6 days. It was found that enzyme activity increased in parallel with an enhancement in the H₂O₂ level in roots exposed to 100 mM NaCl for 1 h, and to 50 mM NaCl for 1 day. The expression of some CsRboh genes was induced by salt. Moreover, an increase in the activity of G6PDH, providing the substrate for the NADPH oxidase, was observed. In seedlings subjected to salinity for a longer time, antioxidant enzymes—including superoxide dismutase, catalase, and ascorbate peroxidase—were activated, participating in maintaining a steady-state H₂O₂ content in the root cells. In conclusion, NADPH oxidase and endogenous H₂O₂ up-regulation seem to be early events in cucumber response to salinity. Full article

(This article belongs to the Special Issue Plant Response and Tolerance to Abiotic Oxidative Stress: Antioxidant Machinery as a Paradigm of Defense)

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20 pages, 5704 KiB

Open AccessArticle

Exogenously Applied Rohitukine Inhibits Photosynthetic Processes, Growth and Induces Antioxidant Defense System in Arabidopsis thaliana

by Sajad Ahmed, Mohd Asgher, Amit Kumar and Sumit G. Gandhi

Antioxidants 2022, 11(8), 1512; https://doi.org/10.3390/antiox11081512 - 03 Aug 2022

Cited by 3 | Viewed by 2097

Abstract

The secondary metabolite rohitukine has been reported in only a few plant species, including Schumanniophyton magnificum, S. problematicum, Amoora rohituka, Dysoxylum acutangulum and D. gotadhora. It has several biological activities, such as anticancer, anti-inflammatory, antiadipogenic, immunomodulatory, gastroprotective, anti-implantation, antidyslipidemic, [...] Read more.

The secondary metabolite rohitukine has been reported in only a few plant species, including Schumanniophyton magnificum, S. problematicum, Amoora rohituka, Dysoxylum acutangulum and D. gotadhora. It has several biological activities, such as anticancer, anti-inflammatory, antiadipogenic, immunomodulatory, gastroprotective, anti-implantation, antidyslipidemic, anti-arthritic and anti-fertility properties. However, the ecological and physiological roles of rohitukine in parent plants have yet to be explored. Here for the first time, we tried to decipher the physiological effect of rohitukine isolated from D. gotadhora on the model system Arabidopsis thaliana. Application of 0.25 mM and 0.5 mM rohitukine concentrations moderately affected the growth of A. thaliana, whereas a remarkable decrease in growth and the alteration of various morphological, physiological and biochemical mechanisms were observed in plants that received 1.0 mM of rohitukine as compared to the untreated control. A. thaliana showed considerable dose-dependent decreases in leaf area, fresh weight and dry weight when sprayed with 0.25 mM, 0.5 mM and 1.0 mM of rohitukine. Rohitukine exposure resulted in the disruption of photosynthesis, photosystem II (PSII) activity and degradation of chlorophyll content in A. thaliana. It also triggered oxidative stress in visualized tissues through antioxidant enzyme activity and the expression levels of key genes involved in the antioxidant system, such as superoxide dismutase (SOD), peroxidase (POD) and ascorbate peroxidase (APX). Rohitukine-induced changes in levels of metabolites (amino acids, sugars, organic acids, etc.) were also assessed. In light of these results, we discuss (i) the likely ecological importance of rohitukine in parent plants as well as (ii) the comparison of responses to rohitukine treatment in plants and mammals. Full article

(This article belongs to the Special Issue Plant Response and Tolerance to Abiotic Oxidative Stress: Antioxidant Machinery as a Paradigm of Defense)

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31 pages, 7711 KiB

Open AccessArticle

Hydrogen Sulfide, Ethylene, and Nitric Oxide Regulate Redox Homeostasis and Protect Photosynthetic Metabolism under High Temperature Stress in Rice Plants

by Harsha Gautam, Mehar Fatma, Zebus Sehar, Iqbal R. Mir and Nafees A. Khan

Antioxidants 2022, 11(8), 1478; https://doi.org/10.3390/antiox11081478 - 28 Jul 2022

Cited by 22 | Viewed by 2284

Abstract

Rising temperatures worldwide due to global climate change are a major scientific issue at present. The present study reports the effects of gaseous signaling molecules, ethylene (200 µL L⁻¹; 2-chloroethylphosphonic acid; ethephon, Eth), nitric oxide (NO; 100 µM sodium nitroprusside; SNP), [...] Read more.

Rising temperatures worldwide due to global climate change are a major scientific issue at present. The present study reports the effects of gaseous signaling molecules, ethylene (200 µL L⁻¹; 2-chloroethylphosphonic acid; ethephon, Eth), nitric oxide (NO; 100 µM sodium nitroprusside; SNP), and hydrogen sulfide (H₂S; 200 µM sodium hydrosulfide, NaHS) in high temperature stress (HS) tolerance, and whether or not H₂S contributes to ethylene or NO-induced thermo-tolerance and photosynthetic protection in rice (Oryza sativa L.) cultivars, i.e., Taipei-309, and Rasi. Plants exposed to an HS of 40 °C for six h per day for 15 days caused a reduction in rice biomass, associated with decreased photosynthesis and leaf water status. High temperature stress increased oxidative stress by increasing the content of hydrogen peroxide (H₂O₂) and thiobarbituric acid reactive substance (TBARS) in rice leaves. These signaling molecules increased biomass, leaf water status, osmolytes, antioxidants, and photosynthesis of plants under non-stress and high temperature stress. However, the effect was more conspicuous with ethylene than NO and H₂S. The application of H₂S scavenger hypotaurine (HT) reversed the effect of ethylene or NO on photosynthesis under HS. This supports the findings that the ameliorating effects of Eth or SNP involved H₂S. Thus, the presence of H₂S with ethylene or NO can enhance thermo-tolerance while also protecting plant photosynthesis. Full article

(This article belongs to the Special Issue Plant Response and Tolerance to Abiotic Oxidative Stress: Antioxidant Machinery as a Paradigm of Defense)

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18 pages, 3235 KiB

Open AccessArticle

BAG9 Confers Thermotolerance by Regulating Cellular Redox Homeostasis and the Stability of Heat Shock Proteins in Solanum lycopersicum

by Huamin Huang, Chenxu Liu, Chen Yang, Mukesh Kumar Kanwar, Shujun Shao, Zhenyu Qi and Jie Zhou

Antioxidants 2022, 11(8), 1467; https://doi.org/10.3390/antiox11081467 - 27 Jul 2022

Cited by 5 | Viewed by 2193

Abstract

The Bcl-2-associated athanogene (BAG) family, a group of co-chaperones that share conservative domains in flora and fauna, is involved in plant growth, development, and stress tolerance. However, the function of tomato BAG genes on thermotolerance remains largely unknown. Herein, we found that the [...] Read more.

The Bcl-2-associated athanogene (BAG) family, a group of co-chaperones that share conservative domains in flora and fauna, is involved in plant growth, development, and stress tolerance. However, the function of tomato BAG genes on thermotolerance remains largely unknown. Herein, we found that the expression of BAG9 was induced during heat stress in tomato plants. Knockout of the BAG9 gene by CRISPR/Cas9 reduced, while its overexpression increased thermotolerance in tomato plants as reflected by the phenotype, photosynthesis rate, and membrane peroxidation. Heat-induced reactive oxygen species and oxidative/oxidized proteins were further increased in bag9 mutants and were normalized in BAG9 overexpressing plants. Furthermore, the activities of antioxidant enzymes, ascorbic acid (AsA)/dehydroascorbic acid (DHA), and reduced glutathione (GSH)/oxidized glutathione (GSSG) were reduced in bag9 mutants and were increased in BAG9 overexpressing plants under heat stress. Additionally, BAG9 interacted with Hsp20 proteins in vitro and in vivo. Accumulation of Hsp proteins induced by heat showed a reduction in bag9 mutants; meanwhile, it was increased in BAG9 overexpressing plants. Thus, BAG9 played a crucial role in response to heat stress by regulating cellular redox homeostasis and the stability of heat shock proteins. Full article

(This article belongs to the Special Issue Plant Response and Tolerance to Abiotic Oxidative Stress: Antioxidant Machinery as a Paradigm of Defense)

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23 pages, 4390 KiB

Open AccessArticle

Comparative Physiological and Transcriptomic Analyses Reveal Mechanisms of Exogenous Spermidine-Induced Tolerance to Low-Iron Stress in Solanum lycopersicum L

by Yu Shi, Yihong Zhao, Qi Yao, Feng Liu, Xiumin Li, Xiu Jin, Yi Zhang and Golam Jalal Ahammed

Antioxidants 2022, 11(7), 1260; https://doi.org/10.3390/antiox11071260 - 27 Jun 2022

Cited by 4 | Viewed by 1975

Abstract

Iron (Fe) deficiency in plants is a major problem in agriculture. Therefore, we investigated both the physiological features and molecular mechanisms of plants’ response to low-Fe (LF) stress along with the mitigation of LF with exogenous spermidine (Spd) in tomato plants. The results [...] Read more.

Iron (Fe) deficiency in plants is a major problem in agriculture. Therefore, we investigated both the physiological features and molecular mechanisms of plants’ response to low-Fe (LF) stress along with the mitigation of LF with exogenous spermidine (Spd) in tomato plants. The results showed that exogenous Spd foliar application relieved the suppressing effect of LF stress on tomato plants by regulating the photosynthetic efficiency, chlorophyll metabolism, antioxidant levels, organic acid secretion, polyamine metabolism and osmoregulatory systems. Analysis of transcriptomic sequencing results revealed that the differentially expressed genes of iron-deficiency stress were mainly enriched in the pathways of phytohormone signaling, starch and sucrose metabolism and phenyl propane biosynthesis in both leaves and roots. Moreover, Spd-induced promotion of growth under LF stress was associated with upregulation in the expression of some transcription factors that are related to growth hormone response in leaves (GH3, SAUR, ARF) and ethylene-related signaling factors in roots (ERF1, ERF2). We propose that traits associated with changes in low-iron-tolerance genes can potentially be used to improve tomato production. The study provides a theoretical basis for dealing with the iron deficiency issue to develop efficient nutrient management strategies in protected tomato cultivation. Full article

(This article belongs to the Special Issue Plant Response and Tolerance to Abiotic Oxidative Stress: Antioxidant Machinery as a Paradigm of Defense)

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15 pages, 2042 KiB

Open AccessArticle

Radio-Protective Effects of Stigmasterol on Wheat (Triticum aestivum L.) Plants

by Hebat-Allah A. Hussein, Shifaa O. Alshammari, Fatma M. Elkady, Amany A. Ramadan, Sahar K. M. Kenawy and Aisha M. Abdelkawy

Antioxidants 2022, 11(6), 1144; https://doi.org/10.3390/antiox11061144 - 10 Jun 2022

Cited by 5 | Viewed by 1806

Abstract

Ionizing radiation is abiotic stress limiting the growth and productivity of crop plants. Stigmasterol has positive effects on the plant growth of many crops. The role of stigmasterol in alleviating the effects of ionizing radiation on plant metabolism and development is still unclear. [...] Read more.

Ionizing radiation is abiotic stress limiting the growth and productivity of crop plants. Stigmasterol has positive effects on the plant growth of many crops. The role of stigmasterol in alleviating the effects of ionizing radiation on plant metabolism and development is still unclear. Therefore, the study aimed to investigate the effects of pretreatments with γ-radiation (0, 25, and 50 Gy), foliar application of stigmasterol (0, 100, and 200 ppm), and their interaction on the growth, and biochemical constituents of wheat (Triticum aestivum L., var. Sids 12) plants. Gamma radiation at 25 Gy showed no significant difference in plant height, root length, no. of leaves, shoot fresh weight, root fresh weight, Chl a, ABA, soluble phenols, and MDA compared to the control values. Gamma rays at 50 Gy inhibited shoot and root lengths, flag leaf area, shoot fresh and dry weights, photosynthetic pigments, total soluble sugars, proline, and peroxidase activity. However, it stimulated total phenols, catalase activity, and lipid peroxidation. On the other hand, stigmasterol at 100 ppm showed no significant effects on some of the physiological attributes compared to control plants. Stigmasterol at 200 ppm improved plant growth parameters, photosynthetic pigments, proline, phenols, antioxidant enzyme, gibberellic acid, and indole acetic acid. Correspondingly, it inhibited total soluble sugars, abscisic acid, and lipid peroxidation. Moreover, the application of stigmasterol caused the appearance of new polypeptides and the reappearance of those missed by gamma radiation. Overall, stigmasterol could alleviate the adverse effects of gamma radiation on wheat plants. Full article

(This article belongs to the Special Issue Plant Response and Tolerance to Abiotic Oxidative Stress: Antioxidant Machinery as a Paradigm of Defense)

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15 pages, 8027 KiB

Open AccessCommunication

Flooding Tolerance in Sweet Potato (Ipomoea batatas (L.) Lam) Is Mediated by Reactive Oxygen Species and Nitric Oxide

by Sul-U Park, Chan-Ju Lee, Sung-Chul Park, Ki Jung Nam, Kang-Lok Lee, Sang-Soo Kwak, Ho Soo Kim and Yun-Hee Kim

Antioxidants 2022, 11(5), 878; https://doi.org/10.3390/antiox11050878 - 29 Apr 2022

Cited by 8 | Viewed by 2315

Abstract

Flooding is harmful to almost all higher plants, including crop species. Most cultivars of the root crop sweet potato are able to tolerate environmental stresses such as drought, high temperature, and high salinity. They are, however, relatively sensitive to flooding stress, which greatly [...] Read more.

Flooding is harmful to almost all higher plants, including crop species. Most cultivars of the root crop sweet potato are able to tolerate environmental stresses such as drought, high temperature, and high salinity. They are, however, relatively sensitive to flooding stress, which greatly reduces yield and commercial value. Previous transcriptomic analysis of flood-sensitive and flood-resistant sweet potato cultivars identified genes that were likely to contribute to protection against flooding stress, including genes related to ethylene (ET), reactive oxygen species (ROS), and nitric oxide (NO) metabolism. Although each sweet potato cultivar can be classified as either tolerant or sensitive to flooding stress, the molecular mechanisms of flooding resistance in ET, ROS, and NO regulation-mediated responses have not yet been reported. Therefore, this study characterized the regulation of ET, ROS, and NO metabolism in two sweet potato cultivars—one flood-tolerant cultivar and one flood-sensitive cultivar—under early flooding treatment conditions. The expression of ERFVII genes, which are involved in low oxygen signaling, was upregulated in leaves during flooding stress treatments. In addition, levels of respiratory burst oxidase homologs and metallothionein-mediated ROS scavenging were greatly increased in the early stage of flooding in the flood-tolerant sweet potato cultivar compared with the flood-sensitive cultivar. The expression of genes involved in NO biosynthesis and scavenging was also upregulated in the tolerant cultivar. Finally, NO scavenging-related MDHAR expressions and enzymatic activity were higher in the flood-tolerant cultivar than in the flood-sensitive cultivar. These results indicate that, in sweet potato, genes involved in ET, ROS, and NO regulation play an important part in response mechanisms against flooding stress. Full article

(This article belongs to the Special Issue Plant Response and Tolerance to Abiotic Oxidative Stress: Antioxidant Machinery as a Paradigm of Defense)

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12 pages, 18548 KiB

Open AccessArticle

Marker-Free Rice (Oryza sativa L. cv. IR 64) Overexpressing PDH45 Gene Confers Salinity Tolerance by Maintaining Photosynthesis and Antioxidant Machinery

by Ranjan Kumar Sahoo, Renu Tuteja, Ritu Gill, Juan Francisco Jiménez Bremont, Sarvajeet Singh Gill and Narendra Tuteja

Antioxidants 2022, 11(4), 770; https://doi.org/10.3390/antiox11040770 - 12 Apr 2022

Cited by 2 | Viewed by 2171

Abstract

Helicases function as key enzymes in salinity stress tolerance, and the role and function of PDH45 (pea DNA helicase 45) in stress tolerance have been reported in different crops with selectable markers, raising public and regulatory concerns. In the present study, we developed [...] Read more.

Helicases function as key enzymes in salinity stress tolerance, and the role and function of PDH45 (pea DNA helicase 45) in stress tolerance have been reported in different crops with selectable markers, raising public and regulatory concerns. In the present study, we developed five lines of marker-free PDH45-overexpressing transgenic lines of rice (Oryza sativa L. cv. IR64). The overexpression of PDH45 driven by CaMV35S promoter in transgenic rice conferred high salinity (200 mM NaCl) tolerance in the T₁ generation. Molecular attributes such as PCR, RT-PCR, and Southern and Western blot analyses confirmed stable integration and expression of the PDH45 gene in the PDH45-overexpressing lines. We observed higher endogenous levels of sugars (glucose and fructose) and hormones (GA, zeatin, and IAA) in the transgenic lines in comparison to control plants (empty vector (VC) and wild type (WT)) under salt treatments. Furthermore, photosynthetic characteristics such as net photosynthetic rate (Pn), stomatal conductance (gs), intercellular CO₂ (Ci), and chlorophyll (Chl) content were significantly higher in transgenic lines under salinity stress as compared to control plants. However, the maximum primary photochemical efficiency of PSII, as an estimated from variable to maximum chlorophyll a fluorescence (Fv/Fm), was identical in the transgenics to that in the control plants. The activities of antioxidant enzymes, such as catalase (CAT), ascorbate peroxidase (APX), glutathione reductase (GR), and guaiacol peroxidase (GPX), were significantly higher in transgenic lines in comparison to control plants, which helped in keeping the oxidative stress burden (MDA and H₂O₂) lesser on transgenic lines, thus protecting the growth and photosynthetic efficiency of the plants. Overall, the present research reports the development of marker-free PDH45-overexpressing transgenic lines for salt tolerance that can potentially avoid public and biosafety concerns and facilitate the commercialization of genetically engineered crop plants. Full article

(This article belongs to the Special Issue Plant Response and Tolerance to Abiotic Oxidative Stress: Antioxidant Machinery as a Paradigm of Defense)

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18 pages, 2492 KiB

Open AccessArticle

Genome-Wide Identification of the Bcl-2 Associated Athanogene (BAG) Gene Family in Solanum lycopersicum and the Functional Role of SlBAG9 in Response to Osmotic Stress

by Hailong Jiang, Yurong Ji, Jiarong Sheng, Yan Wang, Xiaoya Liu, Peixiang Xiao and Haidong Ding

Antioxidants 2022, 11(3), 598; https://doi.org/10.3390/antiox11030598 - 21 Mar 2022

Cited by 9 | Viewed by 2699

Abstract

The Bcl-2-associated athanogene (BAG) proteins are a family of multi-functional group of co-chaperones regulators, modulating diverse processes from plant growth and development to stress response. Here, 10 members of SlBAG gene family were identified based on the available tomato (Solanum lycopersicum) [...] Read more.

The Bcl-2-associated athanogene (BAG) proteins are a family of multi-functional group of co-chaperones regulators, modulating diverse processes from plant growth and development to stress response. Here, 10 members of SlBAG gene family were identified based on the available tomato (Solanum lycopersicum) genomic information and named as SlBAG1-10 according to their chromosomal location. All SlBAG proteins harbor a characteristic BAG domain, categorized into two groups, and SlBAG4, SlBAG7, and SlBAG9 of group I contain a plant-specific isoleucine glutamine (IQ) calmodulin-binding motif located in the N terminus. The quantitative real-time PCR expression analysis revealed that these SlBAG genes had organ-specific expression patterns and most SlBAG genes were differentially expressed in multiple abiotic stresses including drought, salt, high temperature, cold, and cadmium stress as well as abscisic acid and H₂O₂. In addition, heterologous overexpression of SlBAG9 increased the sensitivity of Arabidopsis to drought, salt, and ABA during seed germination and seedling growth. The decreased tolerance may be due to the downregulation of stress-related genes expression and severe oxidative stress. The expression levels of some stress and ABA-related genes, such as ABI3, RD29A, DREB2A, and P5CS1, were significantly inhibited by SlBAG9 overexpression under osmotic stress. Meanwhile, the overexpression of SlBAG9 inhibited the expression of FSD1 and CAT1 under stress conditions and the decreased levels of superoxide dismutase and catalase enzyme activities were detected accompanying the trends in the expression of both genes, which resulted in H₂O₂ accumulation and lipid peroxidation. Taken together, these findings lay a foundation for the future study of the biological function of SlBAG genes in tomato. Full article

(This article belongs to the Special Issue Plant Response and Tolerance to Abiotic Oxidative Stress: Antioxidant Machinery as a Paradigm of Defense)

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15 pages, 24583 KiB

Open AccessArticle

Ethanol Positively Modulates Photosynthetic Traits, Antioxidant Defense and Osmoprotectant Levels to Enhance Drought Acclimatization in Soybean

by Md. Mezanur Rahman, Mohammad Golam Mostofa, Ashim Kumar Das, Touhidur Rahman Anik, Sanjida Sultana Keya, S. M. Ahsan, Md. Arifur Rahman Khan, Minhaz Ahmed, Md. Abiar Rahman, Md. Motaher Hossain and Lam-Son Phan Tran

Antioxidants 2022, 11(3), 516; https://doi.org/10.3390/antiox11030516 - 08 Mar 2022

Cited by 12 | Viewed by 3255

Abstract

Drought is a major environmental threat to agricultural productivity and food security across the world. Therefore, addressing the detrimental effects of drought on vital crops like soybean has a significant impact on sustainable food production. Priming plants with organic compounds is now being [...] Read more.

Drought is a major environmental threat to agricultural productivity and food security across the world. Therefore, addressing the detrimental effects of drought on vital crops like soybean has a significant impact on sustainable food production. Priming plants with organic compounds is now being considered as a promising technique for alleviating the negative effects of drought on plants. In the current study, we evaluated the protective functions of ethanol in enhancing soybean drought tolerance by examining the phenotype, growth attributes, and several physiological and biochemical mechanisms. Our results showed that foliar application of ethanol (20 mM) to drought-stressed soybean plants increased biomass, leaf area per trifoliate, gas exchange features, water-use-efficiency, photosynthetic pigment contents, and leaf relative water content, all of which contributed to the improved growth performance of soybean under drought circumstances. Drought stress, on the other hand, caused significant accumulation of reactive oxygen species (ROS), such as superoxide and hydrogen peroxide, and malondialdehyde, as well as an increase of electrolyte leakage in the leaves, underpinning the evidence of oxidative stress and membrane damage in soybean plants. By comparison, exogenous ethanol reduced the ROS-induced oxidative burden by boosting the activities of antioxidant enzymes, including peroxidase, catalase, glutathione S-transferase, and ascorbate peroxidase, and the content of total flavonoids in soybean leaves exposed to drought stress. Additionally, ethanol supplementation increased the contents of total soluble sugars and free amino acids in the leaves of drought-exposed plants, implying that ethanol likely employed these compounds for osmotic adjustment in soybean under water-shortage conditions. Together, our findings shed light on the ethanol-mediated protective mechanisms by which soybean plants coordinated different morphophysiological and biochemical responses in order to increase their drought tolerance. Full article

(This article belongs to the Special Issue Plant Response and Tolerance to Abiotic Oxidative Stress: Antioxidant Machinery as a Paradigm of Defense)

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15 pages, 2171 KiB

Open AccessArticle

The E3 Ubiquitin Ligase Gene Sl1 Is Critical for Cadmium Tolerance in Solanum lycopersicum L.

by Chen-Xu Liu, Ting Yang, Hui Zhou, Golam Jalal Ahammed, Zhen-Yu Qi and Jie Zhou

Antioxidants 2022, 11(3), 456; https://doi.org/10.3390/antiox11030456 - 25 Feb 2022

Cited by 13 | Viewed by 2624

Abstract

Heavy metal cadmium (Cd) at high concentrations severely disturbs plant growth and development. The E3 ubiquitin ligase involved in protein degradation is critical for plant tolerance to abiotic stress, but the role of E3 ubiquitin ligases in Cd tolerance is largely unknown in [...] Read more.

Heavy metal cadmium (Cd) at high concentrations severely disturbs plant growth and development. The E3 ubiquitin ligase involved in protein degradation is critical for plant tolerance to abiotic stress, but the role of E3 ubiquitin ligases in Cd tolerance is largely unknown in tomato. Here, we characterized an E3 ubiquitin ligase gene Sl1, which was highly expressed in roots under Cd stress in our previous study. The subcellular localization of Sl1 revealed that it was located in plasma membranes. In vitro ubiquitination assays confirmed that Sl1 had E3 ubiquitin ligase activity. Knockout of the Sl1 gene by CRISPR/Cas9 genome editing technology reduced while its overexpression increased Cd tolerance as reflected by the changes in the actual quantum efficiency of PSII photochemistry (Φ_PSII) and hydrogen peroxide (H₂O₂) accumulation. Cd-induced increased activities of antioxidant enzymes including superoxide dismutase (SOD), catalase (CAT), ascorbate peroxidase (APX), and glutathione reductase (GR) were compromised in sl1 mutants but were enhanced in Sl1 overexpressing lines. Furthermore, the content of Cd in both shoots and roots increased in sl1 mutants while reduced in Sl1 overexpressing plants. Gene expression assays revealed that Sl1 regulated the transcript levels of heavy metal transport-related genes to inhibit Cd accumulation. These findings demonstrate that Sl1 plays a critical role in regulating Cd tolerance by relieving oxidative stress and resisting heavy metal transportation in tomato. The study provides a new understanding of the mechanism of plant tolerance to heavy metal stress. Full article

(This article belongs to the Special Issue Plant Response and Tolerance to Abiotic Oxidative Stress: Antioxidant Machinery as a Paradigm of Defense)

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26 pages, 2279 KiB

Open AccessArticle

Co-Application of 24-Epibrassinolide and Titanium Oxide Nanoparticles Promotes Pleioblastus pygmaeus Plant Tolerance to Cu and Cd Toxicity by Increasing Antioxidant Activity and Photosynthetic Capacity and Reducing Heavy Metal Accumulation and Translocation

by Abolghassem Emamverdian, Yulong Ding, James Barker, Guohua Liu, Mirza Hasanuzzaman, Yang Li, Muthusamy Ramakrishnan and Farzad Mokhberdoran

Antioxidants 2022, 11(3), 451; https://doi.org/10.3390/antiox11030451 - 24 Feb 2022

Cited by 15 | Viewed by 2639

Abstract

The integrated application of nanoparticles and phytohormones was explored in this study as a potentially eco-friendly remediation strategy to mitigate heavy metal toxicity in a bamboo species (Pleioblastus pygmaeus) by utilizing titanium oxide nanoparticles (TiO₂-NPs) and 24-epibrassinolide (EBL). Hence, [...] Read more.

The integrated application of nanoparticles and phytohormones was explored in this study as a potentially eco-friendly remediation strategy to mitigate heavy metal toxicity in a bamboo species (Pleioblastus pygmaeus) by utilizing titanium oxide nanoparticles (TiO₂-NPs) and 24-epibrassinolide (EBL). Hence, an in vitro experiment was performed to evaluate the role of 100 µM TiO₂ NPs and 10⁻⁸ M 24-epibrassinolide individually and in combination under 100 µM Cu and Cd in a completely randomized design using four replicates. Whereas 100 µM of Cu and Cd reduced antioxidant activity, photosynthetic capacity, plant tolerance, and ultimately plant growth, the co-application of 100 µM TiO₂ NPs and 10⁻⁸ M EBL+ heavy metals (Cu and Cd) resulted in a significant increase in plant antioxidant activity (85%), nonenzymatic antioxidant activities (47%), photosynthetic pigments (43%), fluorescence parameters (68%), plant growth (39%), and plant tolerance (41%) and a significant reduction in the contents of malondialdehyde (45%), hydrogen peroxide (36%), superoxide radical (62%), and soluble protein (28%), as well as the percentage of electrolyte leakage (49%), relative to the control. Moreover, heavy metal accumulation and translocation were reduced by TiO₂ NPs and EBL individually and in combination, which could improve bamboo plant tolerance. Full article

(This article belongs to the Special Issue Plant Response and Tolerance to Abiotic Oxidative Stress: Antioxidant Machinery as a Paradigm of Defense)

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16 pages, 5205 KiB

Open AccessArticle

Melatonin Improves Drought Stress Tolerance of Tomato by Modulating Plant Growth, Root Architecture, Photosynthesis, and Antioxidant Defense System

by Muhammad Ahsan Altaf, Rabia Shahid, Ming-Xun Ren, Safina Naz, Muhammad Mohsin Altaf, Latif Ullah Khan, Rahul Kumar Tiwari, Milan Kumar Lal, Muhammad Adnan Shahid, Ravinder Kumar, Muhammad Azher Nawaz, Mohammad Shah Jahan, Basit Latief Jan and Parvaiz Ahmad

Antioxidants 2022, 11(2), 309; https://doi.org/10.3390/antiox11020309 - 03 Feb 2022

Cited by 110 | Viewed by 7451

Abstract

Tomato is an important vegetable that is highly sensitive to drought (DR) stress which impairs the development of tomato seedlings. Recently, melatonin (ME) has emerged as a nontoxic, regulatory biomolecule that regulates plant growth and enhances the DR tolerance mechanism in plants. The [...] Read more.

Tomato is an important vegetable that is highly sensitive to drought (DR) stress which impairs the development of tomato seedlings. Recently, melatonin (ME) has emerged as a nontoxic, regulatory biomolecule that regulates plant growth and enhances the DR tolerance mechanism in plants. The present study was conducted to examine the defensive role of ME in photosynthesis, root architecture, and the antioxidant enzymes’ activities of tomato seedlings subjected to DR stress. Our results indicated that DR stress strongly suppressed growth and biomass production, inhibited photosynthesis, negatively affected root morphology, and reduced photosynthetic pigments in tomato seedlings. Per contra, soluble sugars, proline, and ROS (reactive oxygen species) were suggested to be improved in seedlings under DR stress. Conversely, ME (100 µM) pretreatment improved the detrimental-effect of DR by restoring chlorophyll content, root architecture, gas exchange parameters and plant growth attributes compared with DR-group only. Moreover, ME supplementation also mitigated the antioxidant enzymes [APX (ascorbate peroxidase), CAT (catalase), DHAR (dehydroascorbate reductase), GST (glutathione S-transferase), GR (glutathione reductase), MDHAR (monodehydroascorbate reductase), POD (peroxidase), and SOD (superoxide dismutase)], non-enzymatic antioxidant [AsA (ascorbate), DHA (dehydroascorbic acid), GSH (glutathione), and GSSG, (oxidized glutathione)] activities, reduced oxidative damage [EL (electrolyte leakage), H₂O₂ (hydrogen peroxide), MDA (malondialdehyde), and O₂^•− (superoxide ion)] and osmoregulation (soluble sugars and proline) of tomato seedlings, by regulating gene expression for SOD, CAT, APX, GR, POD, GST, DHAR, and MDHAR. These findings determine that ME pretreatment could efficiently improve the seedlings growth, root characteristics, leaf photosynthesis and antioxidant machinery under DR stress and thereby increasing the seedlings’ adaptability to DR stress. Full article

(This article belongs to the Special Issue Plant Response and Tolerance to Abiotic Oxidative Stress: Antioxidant Machinery as a Paradigm of Defense)

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