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Antioxidant Metabolic Pathways in Plants

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A special issue of International Journal of Molecular Sciences (ISSN 1422-0067). This special issue belongs to the section "Molecular Plant Sciences".

Deadline for manuscript submissions: closed (31 March 2020) | Viewed by 40144

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Dr. Ana Jiménez

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Department of Stress Biology and Plant Pathology, Centro de Edafología y Biología Aplicada del Segura (CSIC), Murcia, Spain
Interests: plant antioxidants; organellar antioxidants; abiotic stress; biotic stress; metabolic pathways; new antioxidants; protection; reactive oxygen
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Dear colleagues,

Reactive oxygen especies (ROS) derived from oxygen reduction are key players in the signalling pathways ocurring during plant responses to biotic and abiotic stresses. Associated oxidative processes are mainly controlled by the antioxidant and redox system, and knowledge of the response of their metabolic pathways is crucial for plants in order to cope with growing environmental constraints. Thus, regulation and coordination of antioxidant systems is of special importance for our understanding of plant stress responses.

The purpose of this Special Issue of International Journal of Molecular Science is to provide a current overview of the research on antioxidant metabolic pathways in plants through the contribution of experts in the field of plant antioxidants. For this, you are invited to submit original articles, reviews, and perspectives fosused on this topic, such as the chemistry of plant antioxidants, antioxidants mechanisms, improving plant antioxidants and derived products, antioxidant metabolic pathways involved in stress responses, the relationship between antioxidants and other protective systems, and other related topics. This will allow us to have an overview of the importance for the plant metabolism of these key protective mechanisms, for both basic and applied research.

Dr. Ana Jiménez
Guest Editor

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Keywords

mitochondria

nucleus

thioredoxin

redox signaling

abiotic stress

fruit ripening

RNS

Published Papers (11 papers)

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13 pages, 3819 KiB

Open AccessArticle

Construction of Gossypium barbadense Mutant Library Provides Genetic Resources for Cotton Germplasm Improvement

by Muhammad Ali Abid, Peilin Wang, Tao Zhu, Chengzhen Liang, Zhigang Meng, Waqas Malik, Sandui Guo and Rui Zhang

Int. J. Mol. Sci. 2020, 21(18), 6505; https://doi.org/10.3390/ijms21186505 - 5 Sep 2020

Cited by 8 | Viewed by 3636

Abstract

Allotetraploid cotton (Gossypium hirsutum and Gossypium barbadense) are cultivated worldwide for its white fiber. For centuries, conventional breeding approaches increase cotton yield at the cost of extensive erosion of natural genetic variability. Sea Island cotton (G. barbadense) is known for its superior fiber quality, but show poor adaptability as compared to Upland cotton. Here, in this study, we use ethylmethanesulfonate (EMS) as a mutagenic agent to induce genome-wide point mutations to improve the current germplasm resources of Sea Island cotton and develop diverse breeding lines with improved adaptability and excellent economic traits. We determined the optimal EMS experimental procedure suitable for construction of cotton mutant library. At M₆ generation, mutant library comprised of lines with distinguished phenotypes of the plant architecture, leaf, flower, boll, and fiber. Genome-wide analysis of SNP distribution and density in yellow leaf mutant reflected the better quality of mutant library. Reduced photosynthetic efficiency and transmission electron microscopy of yellow leaf mutants revealed the effect of induced mutations at physiological and cellular level. Our mutant collection will serve as the valuable resource for basic research on cotton functional genomics, as well as cotton breeding. Full article

(This article belongs to the Special Issue Antioxidant Metabolic Pathways in Plants)

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21 pages, 4815 KiB

Open AccessArticle

Kandelia candel Thioredoxin f Confers Osmotic Stress Tolerance in Transgenic Tobacco

by Xiaoshu Jing, Jun Yao, Xujun Ma, Yanli Zhang, Yuanling Sun, Min Xiang, Peichen Hou, Niya Li, Rui Zhao, Jinke Li, Xiaoyang Zhou and Shaoliang Chen

Int. J. Mol. Sci. 2020, 21(9), 3335; https://doi.org/10.3390/ijms21093335 - 8 May 2020

Cited by 7 | Viewed by 2323

Abstract

Water deficit caused by osmotic stress and drought limits crop yield and tree growth worldwide. Screening and identifying candidate genes from stress-resistant species are a genetic engineering strategy to increase drought resistance. In this study, an increased concentration of mannitol resulted in elevated expression of thioredoxin f (KcTrxf) in the nonsecretor mangrove species Kandelia candel. By means of amino acid sequence and phylogenetic analysis, the mangrove Trx was classified as an f-type thioredoxin. Subcellular localization showed that KcTrxf localizes to chloroplasts. Enzymatic activity characterization revealed that KcTrxf recombinant protein possesses the disulfide reductase function. KcTrxf overexpression contributes to osmotic and drought tolerance in tobacco in terms of fresh weight, root length, malondialdehyde (MDA) content, and hydrogen peroxide (H₂O₂) production. KcTrxf was shown to reduce the stomatal aperture by enhancing K⁺ efflux in guard cells, which increased the water-retaining capacity in leaves under drought conditions. Notably, the abscisic acid (ABA) sensitivity was increased in KcTrxf-transgenic tobacco, which benefits plants exposed to drought by reducing water loss by promoting stomatal closure. KcTrxf-transgenic plants limited drought-induced H₂O₂ in leaves, which could reduce lipid peroxidation and retain the membrane integrity. Additionally, glutathione (GSH) contributing to reactive oxygen species (ROS) scavenging and transgenic plants are more efficient at regenerating GSH from oxidized glutathione (GSSG) under conditions of drought stress. Notably, KcTrxf-transgenic plants had increased glucose and fructose contents under drought stress conditions, presumably resulting from KcTrxf-promoted starch degradation under water stress. We conclude that KcTrxf contributes to drought tolerance by increasing the water status, by enhancing osmotic adjustment, and by maintaining ROS homeostasis in transgene plants. Full article

(This article belongs to the Special Issue Antioxidant Metabolic Pathways in Plants)

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18 pages, 4987 KiB

Open AccessArticle

Chemical Defoliant Promotes Leaf Abscission by Altering ROS Metabolism and Photosynthetic Efficiency in Gossypium hirsutum

by Dingsha Jin, Xiangru Wang, Yanchao Xu, Huiping Gui, Hengheng Zhang, Qiang Dong, Ripon Kumar Sikder, Guozheng Yang and Meizhen Song

Int. J. Mol. Sci. 2020, 21(8), 2738; https://doi.org/10.3390/ijms21082738 - 15 Apr 2020

Cited by 31 | Viewed by 3324

Abstract

Chemical defoliation is an important part of cotton mechanical harvesting, which can effectively reduce the impurity content. Thidiazuron (TDZ) is the most used chemical defoliant on cotton. To better clarify the mechanism of TDZ promoting cotton leaf abscission, a greenhouse experiment was conducted on two cotton cultivars (CRI 12 and CRI 49) by using 100 mg L⁻¹ TDZ at the eight-true-leaf stage. Results showed that TDZ significantly promoted the formation of leaf abscission zone and leaf abscission. Although the antioxidant enzyme activities were improved, the reactive oxygen species and malondialdehyde (MDA) contents of TDZ increased significantly compared with CK (water). The photosynthesis system was destroyed as net photosynthesis (Pn), transpiration rate (Tr), and stomatal conductance (Gs) decreased dramatically by TDZ. Furthermore, comparative RNA-seq analysis of the leaves showed that all of the photosynthetic related genes were downregulated and the oxidation-reduction process participated in leaf shedding caused by TDZ. Consequently, a hypothesis involving possible cross-talk between ROS metabolism and photosynthesis jointly regulating cotton leaf abscission is proposed. Our findings not only provide important insights into leaf shedding-associated changes induced by TDZ in cotton, but also highlight the possibility that the ROS and photosynthesis may play a critical role in the organ shedding process in other crops. Full article

(This article belongs to the Special Issue Antioxidant Metabolic Pathways in Plants)

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19 pages, 9975 KiB

Open AccessArticle

Transcriptomic Analysis of Ficus carica Peels with a Focus on the Key Genes for Anthocyanin Biosynthesis

by Jing Li, Yuyan An and Liangju Wang

Int. J. Mol. Sci. 2020, 21(4), 1245; https://doi.org/10.3390/ijms21041245 - 13 Feb 2020

Cited by 22 | Viewed by 4627

Abstract

Fig (Ficus carica L.), a deciduous fruit tree of the Moraceae, provides ingredients for human health such as anthocyanins. However, little information is available on its molecular structure. In this study, the fig peels in the yellow (Y) and red (R) stages were used for transcriptomic analyses. Comparing the R with the Y stage, we obtained 6224 differentially expressed genes, specifically, anthocyanin-related genes including five CHS, three CHI, three DFR, three ANS, two UFGT and seven R2R3-MYB genes. Furthermore, three anthocyanin biosynthetic genes, i.e., FcCHS1, FcCHI1 and FcDFR1, and two R2R3-MYB genes, i.e., FcMYB21 and FcMYB123, were cloned; sequences analysis and their molecular characteristics indicated their important roles in fig anthocyanin biosynthesis. Heterologous expression of FcMYB21 and FcMYB123 significantly promoted anthocyanin accumulation in both apple fruits and calli, further suggesting their regulatory roles in fig coloration. These findings provide novel insights into the molecular mechanisms behind fig anthocyanin biosynthesis and coloration, facilitating the genetic improvement of high-anthocyanin cultivars and other horticultural traits in fig fruits. Full article

(This article belongs to the Special Issue Antioxidant Metabolic Pathways in Plants)

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18 pages, 3523 KiB

Open AccessArticle

Nano-ZnO-Induced Drought Tolerance Is Associated with Melatonin Synthesis and Metabolism in Maize

by Luying Sun, Fengbin Song, Junhong Guo, Xiancan Zhu, Shengqun Liu, Fulai Liu and Xiangnan Li

Int. J. Mol. Sci. 2020, 21(3), 782; https://doi.org/10.3390/ijms21030782 - 25 Jan 2020

Cited by 104 | Viewed by 4760

Abstract

The applications of ZnO nanoparticles in agriculture have largely contributed to crop growth regulation, quality enhancement, and induction of stress tolerance, while the underlying mechanisms remain elusive. Herein, the involvement of melatonin synthesis and metabolism in the process of nano-ZnO induced drought tolerance was investigated in maize. Drought stress resulted in the changes of subcellular ultrastructure, the accumulation of malondialdehyde and osmolytes in leaf. The nano-ZnO (100 mg L⁻¹) application promoted the melatonin synthesis and activated the antioxidant enzyme system, which alleviated drought-induced damage to mitochondria and chloroplast. These changes were associated with upregulation of the relative transcript abundance of Fe/Mn SOD, Cu/Zn SOD, APX, CAT, TDC, SNAT, COMT, and ASMT induced by nano-ZnO application. It was suggested that modifications in endogenous melatonin synthesis were involved in the nano-ZnO induced drought tolerance in maize. Full article

(This article belongs to the Special Issue Antioxidant Metabolic Pathways in Plants)

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27 pages, 4916 KiB

Open AccessArticle

Changes in Proteome and Protein Phosphorylation Reveal the Protective Roles of Exogenous Nitrogen in Alleviating Cadmium Toxicity in Poplar Plants

by Jinliang Huang, Xiaolu Wu, Feifei Tian, Qi Chen, Pengrui Luo, Fan Zhang, Xueqin Wan, Yu Zhong, Qinglin Liu and Tiantian Lin

Int. J. Mol. Sci. 2020, 21(1), 278; https://doi.org/10.3390/ijms21010278 - 31 Dec 2019

Cited by 30 | Viewed by 3314

Abstract

Phytoremediation soil polluted by cadmium has drawn worldwide attention. However, how to improve the efficiency of plant remediation of cadmium contaminated soil remains unknown. Previous studies showed that nitrogen (N) significantly enhances cadmium uptake and accumulation in poplar plants. In order to explore the important role of nitrogen in plants’ responses to cadmium stress, this study investigates the poplar proteome and phosphoproteome difference between Cd stress and Cd + N treatment. In total, 6573 proteins were identified, and 5838 of them were quantified. With a fold-change threshold of > 1.3, and a p-value < 0.05, 375 and 108 proteins were up- and down-regulated by Cd stress when compared to the control, respectively. Compared to the Cd stress group, 42 and 89 proteins were up- and down-regulated by Cd + N treatment, respectively. Moreover, 522 and 127 proteins were up- and down-regulated by Cd + N treatment compared to the CK group. In addition, 1471 phosphosites in 721 proteins were identified. Based on a fold-change threshold of > 1.2, and a p-value < 0.05, the Cd stress up-regulated eight proteins containing eight phosphosites, and down-regulated 58 proteins containing 69 phosphosites, whereas N + Cd treatment up-regulated 86 proteins containing 95 phosphosites, and down-regulated 17 proteins containing 17 phosphosites, when compared to Cd stress alone. N + Cd treatment up-regulated 60 proteins containing 74 phosphosites and down-regulated 37 proteins containing 42 phosphosites, when compared to the control. Several putative responses to stress proteins, as well as transcriptional and translational regulation factors, were up-regulated by the addition of exogenous nitrogen following Cd stress. Especially, heat shock protein 70 (HSP70), 14-3-3 protein, peroxidase (POD), zinc finger protein (ZFP), ABC transporter protein, eukaryotic translation initiation factor (elF) and splicing factor 3 B subunit 1-like (SF3BI) were up-regulated by Cd + N treatment at both the proteome and the phosphoproteome levels. Combing the proteomic data and phosphoproteomics data, the mechanism by which exogenous nitrogen can alleviate cadmium toxicity in poplar plants was explained at the molecular level. The results of this study will establish the solid molecular foundation of the phytoremediation method to improve cadmium-contaminated soil. Full article

(This article belongs to the Special Issue Antioxidant Metabolic Pathways in Plants)

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20 pages, 6341 KiB

Open AccessArticle

Effects of Stripe Rust Infection on the Levels of Redox Balance and Photosynthetic Capacities in Wheat

by Yanger Chen, Haotian Mao, Nan Wu, Jie Ma, Ming Yuan, Zhongwei Zhang, Shu Yuan and Huaiyu Zhang

Int. J. Mol. Sci. 2020, 21(1), 268; https://doi.org/10.3390/ijms21010268 - 31 Dec 2019

Cited by 12 | Viewed by 2634

Abstract

Wheat stripe rust (Puccinia striiformis f. sp. tritici, Pst) is the most destructive wheat disease and a major problem for the productivity of wheat in the world. To obtain a better understanding about different effects of redox homeostasis and photosystem (PS) to Pst infection in wheat, we investigated the differences in photosynthesis and the antioxidant defense system in wheat cultivar Chuanmai42 (CM42) in response to two Chinese Pst races known as CYR32 and V26. The results showed that V26-infected wheat accumulated a higher reactive oxygen species (ROS), cell death, and energy dissipation than CYR32-infected wheat when compared with the control. Furthermore, we found that the activities of three antioxidant enzymes (APX, GR, and GPX) and four resistance-related enzymes in CYR32-infected wheat were significantly higher than that in V26-infected wheat. In addition, quantitative RT-PCR indicated that the expression levels of two genes associated with resistant stripe rust in CYR32-infected wheat were clearly higher than that in V26-infected wheat. Compared with CYR32-infected wheat, lower photochemical efficiencies were observed in V26-infected wheat at the adult stage. Meanwhile, only a marked decline in D1 protein was observed in V26-infected wheat. We therefore deduced that wheat with stripe rust resistance could maintain high resistance and photosynthetic capacity by regulating the antioxidant system, disease-resistant related enzymes and genes, and the levels of PSII reaction center proteins. Full article

(This article belongs to the Special Issue Antioxidant Metabolic Pathways in Plants)

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15 pages, 4158 KiB

Open AccessArticle

NtMYB3, an R2R3-MYB from Narcissus, Regulates Flavonoid Biosynthesis

by Muhammad Anwar, Weijun Yu, Hong Yao, Ping Zhou, Andrew C. Allan and Lihui Zeng

Int. J. Mol. Sci. 2019, 20(21), 5456; https://doi.org/10.3390/ijms20215456 - 1 Nov 2019

Cited by 50 | Viewed by 3668

Abstract

R2R3-MYB transcription factors play important roles in the regulation of plant flavonoid metabolites. In the current study, NtMYB3, a novel R2R3-MYB transcriptional factor isolated from Chinese narcissus (Narcissus tazetta L. var. chinensis), was functionally characterized. Phylogenetic analysis indicated that NtMYB3 belongs to the AtMYB4-like clade, which includes repressor MYBs involved in the regulation of flavonoid biosynthesis. Transient assays showed that NtMYB3 significantly reduced red pigmentation induced by the potato anthocyanin activator StMYB-AN1 in agro-infiltrated leaves of tobacco. Over-expression of NtMYB3 decreased the red color of transgenic tobacco flowers, with qRT-PCR analysis showing that NtMYB3 repressed the expression levels of genes involved in anthocyanin and flavonol biosynthesis. However, the proanthocyanin content in flowers of transgenic tobacco increased as compared to wild type. NtMYB3 showed expression in all examined narcissus tissues; the expression level in basal plates of the bulb was highest. A 968 bp promoter fragment of narcissus FLS (NtFLS) was cloned, and transient expression and dual luciferase assays showed NtMYB3 repressed the promoter activity. These results reveal that NtMYB3 is involved in the regulation of flavonoid biosynthesis in narcissus by repressing the biosynthesis of flavonols, and this leads to proanthocyanin accumulation in the basal plate of narcissus. Full article

(This article belongs to the Special Issue Antioxidant Metabolic Pathways in Plants)

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13 pages, 1611 KiB

Open AccessArticle

Comprehensive Influences of Overexpression of a MYB Transcriptor Regulating Anthocyanin Biosynthesis on Transcriptome and Metabolome of Tobacco Leaves

by Yuan Zong, Shiming Li, Xinyuan Xi, Dong Cao, Zhong Wang, Ran Wang and Baolong Liu

Int. J. Mol. Sci. 2019, 20(20), 5123; https://doi.org/10.3390/ijms20205123 - 16 Oct 2019

Cited by 22 | Viewed by 3338

Abstract

Overexpression of R2R3-MYB transcriptor can induce up-expression of anthocyanin biosynthesis structural genes, and improve the anthocyanin content in plant tissues, but it is not clear whether the MYB transcription factor overexpression does effect on other genes transcript and chemical compounds accumulation. In this manuscript, RNA-sequencing and the stepwise multiple ion monitoring-enhanced product ions (stepwise MIM-EPI) strategy were employed to evaluate the comprehensive effect of the MYB transcription factor LrAN2 in tobacco. Overexpression of LrAN2 could promote anthocyanin accumulation in a lot of tissues of tobacco cultivar Samsun. Only 185 unigenes express differently in a total of 160,965 unigenes in leaves, and 224 chemical compounds were differently accumulated. Three anthocyanins, apigeninidin chloride, pelargonidin 3-O-beta-D-glucoside and cyanidin 3,5-O-diglucoside, were detected only in transgenic lines, which could explain the phenotype of purple leaves. Except for anthocyanins, the phenylpropanoid, polyphenol (catechin), flavonoid, flavone and flavonol, belong to the same subgroups of flavonoids biosynthesis pathway with anthocyanin and were also up-accumulated. Overexpression of LrAN2 activated the bHLH (basic helix-loop-helix protein) transcription factor AN1b, relative to anthocyanin biosynthesis and the MYB transcription factor MYB3, relative to proanthocyanin biosynthesis. Then, the structural genes, relative to the phenylpropanoid pathway, were activated, which led to the up-accumulation of phenylpropanoid, polyphenol (catechin), flavonoid, flavone, flavonol and anthocyanin. The MYB transcription factor CPC, negative to anthocyanin biosynthesis, also induced up-expression in transgenic lines, which implied that a negative regulation mechanism existed in the anthocyanin biosynthesis pathway. The relative contents of all 19 differently accumulated amino and derivers were decreased in transgenic lines, which meant the phenylalanine biosynthesis pathway completed the same substrates with other amino acids. Interestingly, the acetylalkylglycerol acetylhydrolase was down-expressed in transgenic lines, which caused 19 lyso-phosphatidylcholine and derivatives of lipids to be up-accumulated, and 8 octodecane and derivatives were down-accumulated. This research will give more information about the function of MYB transcription factors on the anthocyanin biosynthesis and other chemical compounds and be of benefit to obtaining new plant cultivars with high anthocyanin content by biotechnology. Full article

(This article belongs to the Special Issue Antioxidant Metabolic Pathways in Plants)

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17 pages, 2345 KiB

Open AccessArticle

Physiological and Metabolomic Responses of Kale to Combined Chilling and UV-A Treatment

by Jin-Hui Lee, Min Cheol Kwon, Eun Sung Jung, Choong Hwan Lee and Myung-Min Oh

Int. J. Mol. Sci. 2019, 20(19), 4950; https://doi.org/10.3390/ijms20194950 - 8 Oct 2019

Cited by 12 | Viewed by 3162

Abstract

Short-term abiotic stress treatment before harvest can enhance the quality of horticultural crops cultivated in controlled environments. Here, we investigated the effects of combined chilling and UV-A treatment on the accumulation of phenolic compounds in kale (Brassica oleracea var. acephala). Five-week-old plants were subjected to combined treatments (10 °C plus UV-A LED radiation at 30.3 W/m²) for 3-days, as well as single treatments (4 °C, 10 °C, or UV-A LED radiation). The growth parameters and photosynthetic rates of plants under the combined treatment were similar to those of the control, whereas UV-A treatment alone significantly increased these parameters. Maximum quantum yield (Fv/Fm) decreased and H₂O₂ increased in response to UV-A and combined treatments, implying that these treatments induced stress in kale. The total phenolic contents after 2- and 3-days of combined treatment and 1-day of recovery were 40%, 60%, and 50% higher than those of the control, respectively, and the phenylalanine ammonia-lyase activity also increased. Principal component analysis suggested that stress type and period determine the changes in secondary metabolites. Three days of combined stress treatment followed by 2-days of recovery increased the contents of quercetin derivatives. Therefore, combined chilling and UV-A treatment could improve the phenolic contents of leafy vegetables such as kale, without growth inhibition. Full article

(This article belongs to the Special Issue Antioxidant Metabolic Pathways in Plants)

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Review

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26 pages, 1410 KiB

Open AccessReview

Manipulation of Ascorbate Biosynthetic, Recycling, and Regulatory Pathways for Improved Abiotic Stress Tolerance in Plants

by Ronan C. Broad, Julien P. Bonneau, Roger P. Hellens and Alexander A.T. Johnson

Int. J. Mol. Sci. 2020, 21(5), 1790; https://doi.org/10.3390/ijms21051790 - 5 Mar 2020

Cited by 46 | Viewed by 4838

Abstract

Abiotic stresses, such as drought, salinity, and extreme temperatures, are major limiting factors in global crop productivity and are predicted to be exacerbated by climate change. The overproduction of reactive oxygen species (ROS) is a common consequence of many abiotic stresses. Ascorbate, also known as vitamin C, is the most abundant water-soluble antioxidant in plant cells and can combat oxidative stress directly as a ROS scavenger, or through the ascorbate–glutathione cycle—a major antioxidant system in plant cells. Engineering crops with enhanced ascorbate concentrations therefore has the potential to promote broad abiotic stress tolerance. Three distinct strategies have been utilized to increase ascorbate concentrations in plants: (i) increased biosynthesis, (ii) enhanced recycling, or (iii) modulating regulatory factors. Here, we review the genetic pathways underlying ascorbate biosynthesis, recycling, and regulation in plants, including a summary of all metabolic engineering strategies utilized to date to increase ascorbate concentrations in model and crop species. We then highlight transgene-free strategies utilizing genome editing tools to increase ascorbate concentrations in crops, such as editing the highly conserved upstream open reading frame that controls translation of the GDP-L-galactose phosphorylase gene. Full article

(This article belongs to the Special Issue Antioxidant Metabolic Pathways in Plants)

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