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Smirnoff N, Wheeler GL. The ascorbate biosynthesis pathway in plants is known, but there is a way to go with understanding control and functions. JOURNAL OF EXPERIMENTAL BOTANY 2024; 75:2604-2630. [PMID: 38300237 PMCID: PMC11066809 DOI: 10.1093/jxb/erad505] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/09/2023] [Accepted: 01/29/2024] [Indexed: 02/02/2024]
Abstract
Ascorbate (vitamin C) is one of the most abundant primary metabolites in plants. Its complex chemistry enables it to function as an antioxidant, as a free radical scavenger, and as a reductant for iron and copper. Ascorbate biosynthesis occurs via the mannose/l-galactose pathway in green plants, and the evidence for this pathway being the major route is reviewed. Ascorbate accumulation is leaves is responsive to light, reflecting various roles in photoprotection. GDP-l-galactose phosphorylase (GGP) is the first dedicated step in the pathway and is important in controlling ascorbate synthesis. Its expression is determined by a combination of transcription and translation. Translation is controlled by an upstream open reading frame (uORF) which blocks translation of the main GGP-coding sequence, possibly in an ascorbate-dependent manner. GGP associates with a PAS-LOV protein, inhibiting its activity, and dissociation is induced by blue light. While low ascorbate mutants are susceptible to oxidative stress, they grow nearly normally. In contrast, mutants lacking ascorbate do not grow unless rescued by supplementation. Further research should investigate possible basal functions of ascorbate in severely deficient plants involving prevention of iron overoxidation in 2-oxoglutarate-dependent dioxygenases and iron mobilization during seed development and germination.
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Affiliation(s)
- Nicholas Smirnoff
- Biosciences, Faculty of Health and Life Sciences, Exeter EX4 4QD, UK
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2
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Liao G, Xu Q, Allan AC, Xu X. L-Ascorbic acid metabolism and regulation in fruit crops. PLANT PHYSIOLOGY 2023; 192:1684-1695. [PMID: 37073491 PMCID: PMC10315321 DOI: 10.1093/plphys/kiad241] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/06/2023] [Revised: 04/03/2023] [Accepted: 04/10/2023] [Indexed: 05/03/2023]
Abstract
L-Ascorbic acid (AsA) is more commonly known as vitamin C and is an indispensable compound for human health. As a major antioxidant, AsA not only maintains redox balance and resists biological and abiotic stress but also regulates plant growth, induces flowering, and delays senescence through complex signal transduction networks. However, AsA content varies greatly in horticultural crops, especially in fruit crops. The AsA content of the highest species is approximately 1,800 times higher than that of the lowest species. There have been significant advancements in the understanding of AsA accumulation in the past 20 years. The most noteworthy accomplishment was the identification of the critical rate-limiting genes for the 2 major AsA synthesis pathways (L-galactose pathway and D-galacturonic acid pathway) in fruit crops. The rate-limiting genes of the former are GMP, GME, GGP, and GPP, and the rate-limiting gene of the latter is GalUR. Moreover, APX, MDHAR, and DHAR are also regarded as key genes in degradation and regeneration pathways. Interestingly, some of these key genes are sensitive to environmental factors, such as GGP being induced by light. The efficiency of enhancing AsA content is high by editing upstream open reading frames (uORF) of the key genes and constructing multi-gene expression vectors. In summary, the AsA metabolism has been well understood in fruit crops, but the transport mechanism of AsA and the synergistic improvement of AsA and other traits is less known, which will be the focus of AsA research in fruit crops.
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Affiliation(s)
- Guanglian Liao
- National Key Laboratory for Germplasm Innovation & Utilization of Horticultural Crops, Huazhong Agricultural University, Wuhan, Hubei 430070, PR China
- Kiwifruit Institute, Jiangxi Agricultural University, Nanchang, Jiangxi 330045, PR China
| | - Qiang Xu
- National Key Laboratory for Germplasm Innovation & Utilization of Horticultural Crops, Huazhong Agricultural University, Wuhan, Hubei 430070, PR China
| | - Andrew C Allan
- The New Zealand Institute for Plant and Food Research Limited (Plant & Food Research) Mt Albert, Private Bag 92169, Auckland Mail Centre, Auckland 1142, New Zealand
- School of Biological Sciences, University of Auckland, Private Bag 92019, Auckland, New Zealand
| | - Xiaobiao Xu
- Kiwifruit Institute, Jiangxi Agricultural University, Nanchang, Jiangxi 330045, PR China
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3
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Wang C, Liu X, Chen F, Yue L, Cao X, Li J, Cheng B, Wang Z, Xing B. Selenium content and nutritional quality of Brassica chinensis L enhanced by selenium engineered nanomaterials: The role of surface charge. ENVIRONMENTAL POLLUTION (BARKING, ESSEX : 1987) 2022; 308:119582. [PMID: 35671896 DOI: 10.1016/j.envpol.2022.119582] [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: 03/08/2022] [Revised: 05/30/2022] [Accepted: 06/02/2022] [Indexed: 06/15/2023]
Abstract
Selenium engineered nanomaterials (Se ENMs)-enabled agriculture has developed rapidly, however, the roles of surface charge in the bioavailability and enrichment efficiency of Se ENMs are still unknown. Herein, various Se ENMs of homogenous size (40-60 nm) and different surface charges (3.2 ± 0.7, -29.0 ± 0.4, and 45.5 ± 1.3 mV) were prepared to explore the Se content and nutritional quality in Brassica chinensis L. The results demonstrated that soil application of various Se ENMs (0.05 mg kg-1) displayed different bio-availabilities via modulating the secretion of root exudates (e.g., tartaric, malic, and citric acids), microbial community composition (e.g., Flavobacterium, Pseudomonas, Paracoccus, Bacillus and Rhizobium) and root cell wall. Negatively charged Se ENMs (Se (-)) showed the highest Se content in the shoot of B. chinensis (3.7-folds). Se (-) also significantly increased yield (156.9%) and improved nutritional quality (e.g., ascorbic acid, amino acids, flavonoids, fatty acids, and tricarboxylic acid) of B. chinensis. Moreover, after harvest, the Se (-) did not lead to significant change in Se residue in soil, but the amount of Se residue in soil was increased by 5.5% after applying the traditional Se fertilizer (selenite). Therefore, this study provides useful information for producing Se-fortified agricultural products, while minimizing environmental risk.
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Affiliation(s)
- Chuanxi Wang
- Institute of Environmental Processes and Pollution Control, School of Environment and Civil Engineering, Jiangnan University, Wuxi, Jiangsu, 214122, China; Jiangsu Engineering Laboratory for Biomass Energy and Carbon Reduction Technology, Jiangnan University, Wuxi, Jiangsu, 214122, China; Jiangsu Key Laboratory of Anaerobic Biotechnology, Jiangnan University, Wuxi, Jiangsu, 214122, China
| | - Xiaofei Liu
- Institute of Environmental Processes and Pollution Control, School of Environment and Civil Engineering, Jiangnan University, Wuxi, Jiangsu, 214122, China; Jiangsu Engineering Laboratory for Biomass Energy and Carbon Reduction Technology, Jiangnan University, Wuxi, Jiangsu, 214122, China; Jiangsu Key Laboratory of Anaerobic Biotechnology, Jiangnan University, Wuxi, Jiangsu, 214122, China
| | - Feiran Chen
- Institute of Environmental Processes and Pollution Control, School of Environment and Civil Engineering, Jiangnan University, Wuxi, Jiangsu, 214122, China; Jiangsu Engineering Laboratory for Biomass Energy and Carbon Reduction Technology, Jiangnan University, Wuxi, Jiangsu, 214122, China; Jiangsu Key Laboratory of Anaerobic Biotechnology, Jiangnan University, Wuxi, Jiangsu, 214122, China
| | - Le Yue
- Institute of Environmental Processes and Pollution Control, School of Environment and Civil Engineering, Jiangnan University, Wuxi, Jiangsu, 214122, China; Jiangsu Engineering Laboratory for Biomass Energy and Carbon Reduction Technology, Jiangnan University, Wuxi, Jiangsu, 214122, China; Jiangsu Key Laboratory of Anaerobic Biotechnology, Jiangnan University, Wuxi, Jiangsu, 214122, China
| | - Xuesong Cao
- Institute of Environmental Processes and Pollution Control, School of Environment and Civil Engineering, Jiangnan University, Wuxi, Jiangsu, 214122, China; Jiangsu Engineering Laboratory for Biomass Energy and Carbon Reduction Technology, Jiangnan University, Wuxi, Jiangsu, 214122, China; Jiangsu Key Laboratory of Anaerobic Biotechnology, Jiangnan University, Wuxi, Jiangsu, 214122, China
| | - Jing Li
- Institute of Environmental Processes and Pollution Control, School of Environment and Civil Engineering, Jiangnan University, Wuxi, Jiangsu, 214122, China; Jiangsu Engineering Laboratory for Biomass Energy and Carbon Reduction Technology, Jiangnan University, Wuxi, Jiangsu, 214122, China; Jiangsu Key Laboratory of Anaerobic Biotechnology, Jiangnan University, Wuxi, Jiangsu, 214122, China
| | - Bingxu Cheng
- Institute of Environmental Processes and Pollution Control, School of Environment and Civil Engineering, Jiangnan University, Wuxi, Jiangsu, 214122, China; Jiangsu Engineering Laboratory for Biomass Energy and Carbon Reduction Technology, Jiangnan University, Wuxi, Jiangsu, 214122, China; Jiangsu Key Laboratory of Anaerobic Biotechnology, Jiangnan University, Wuxi, Jiangsu, 214122, China
| | - Zhenyu Wang
- Institute of Environmental Processes and Pollution Control, School of Environment and Civil Engineering, Jiangnan University, Wuxi, Jiangsu, 214122, China; Jiangsu Engineering Laboratory for Biomass Energy and Carbon Reduction Technology, Jiangnan University, Wuxi, Jiangsu, 214122, China; Jiangsu Key Laboratory of Anaerobic Biotechnology, Jiangnan University, Wuxi, Jiangsu, 214122, China.
| | - Baoshan Xing
- Stockbridge School of Agriculture, University of Massachusetts, Amherst, MA 01003, USA
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4
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Zheng X, Gong M, Zhang Q, Tan H, Li L, Tang Y, Li Z, Peng M, Deng W. Metabolism and Regulation of Ascorbic Acid in Fruits. PLANTS (BASEL, SWITZERLAND) 2022; 11:plants11121602. [PMID: 35736753 PMCID: PMC9228137 DOI: 10.3390/plants11121602] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/30/2022] [Revised: 05/26/2022] [Accepted: 06/14/2022] [Indexed: 05/17/2023]
Abstract
Ascorbic acid, also known as vitamin C, is a vital antioxidant widely found in plants. Plant fruits are rich in ascorbic acid and are the primary source of human intake of ascorbic acid. Ascorbic acid affects fruit ripening and stress resistance and plays an essential regulatory role in fruit development and postharvest storage. The ascorbic acid metabolic pathway in plants has been extensively studied. Ascorbic acid accumulation in fruits can be effectively regulated by genetic engineering technology. The accumulation of ascorbic acid in fruits is regulated by transcription factors, protein interactions, phytohormones, and environmental factors, but the research on the regulatory mechanism is still relatively weak. This paper systematically reviews the regulation mechanism of ascorbic acid metabolism in fruits in recent decades. It provides a rich theoretical basis for an in-depth study of the critical role of ascorbic acid in fruits and the cultivation of fruits rich in ascorbic acid.
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Affiliation(s)
- Xianzhe Zheng
- Key Laboratory of Plant Hormones and Development Regulation of Chongqing, School of Life Sciences, Chongqing University, Chongqing 400044, China; (X.Z.); (M.G.); (Q.Z.); (Z.L.)
| | - Min Gong
- Key Laboratory of Plant Hormones and Development Regulation of Chongqing, School of Life Sciences, Chongqing University, Chongqing 400044, China; (X.Z.); (M.G.); (Q.Z.); (Z.L.)
| | - Qiongdan Zhang
- Key Laboratory of Plant Hormones and Development Regulation of Chongqing, School of Life Sciences, Chongqing University, Chongqing 400044, China; (X.Z.); (M.G.); (Q.Z.); (Z.L.)
| | - Huaqiang Tan
- Institute of Horticulture, Chengdu Academy of Agriculture and Forestry Sciences, Chengdu 611130, China; (H.T.); (L.L.); (Y.T.)
| | - Liping Li
- Institute of Horticulture, Chengdu Academy of Agriculture and Forestry Sciences, Chengdu 611130, China; (H.T.); (L.L.); (Y.T.)
| | - Youwan Tang
- Institute of Horticulture, Chengdu Academy of Agriculture and Forestry Sciences, Chengdu 611130, China; (H.T.); (L.L.); (Y.T.)
| | - Zhengguo Li
- Key Laboratory of Plant Hormones and Development Regulation of Chongqing, School of Life Sciences, Chongqing University, Chongqing 400044, China; (X.Z.); (M.G.); (Q.Z.); (Z.L.)
| | - Mingchao Peng
- Institute of Horticulture, Chengdu Academy of Agriculture and Forestry Sciences, Chengdu 611130, China; (H.T.); (L.L.); (Y.T.)
- Correspondence: (M.P.); (W.D.); Tel.: +86-19981296016 (M.P.); +86-18623127580 (W.D.)
| | - Wei Deng
- Key Laboratory of Plant Hormones and Development Regulation of Chongqing, School of Life Sciences, Chongqing University, Chongqing 400044, China; (X.Z.); (M.G.); (Q.Z.); (Z.L.)
- Correspondence: (M.P.); (W.D.); Tel.: +86-19981296016 (M.P.); +86-18623127580 (W.D.)
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5
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Foyer CH, Kyndt T, Hancock RD. Vitamin C in Plants: Novel Concepts, New Perspectives, and Outstanding Issues. Antioxid Redox Signal 2020; 32:463-485. [PMID: 31701753 DOI: 10.1089/ars.2019.7819] [Citation(s) in RCA: 53] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Significance: The concept that vitamin C (l-ascorbic acid) is at the heart of the peroxide processing and redox signaling hub in plants is well established, but our knowledge of the precise mechanisms involved remains patchy at best. Recent Advances: Ascorbate participates in the multifaceted signaling pathways initiated by both reactive oxygen species (ROS) and reactive nitrogen species. Crucially, the apoplastic ascorbate/dehydroascorbate (DHA) ratio that is regulated by ascorbate oxidase (AO) sculpts the apoplastic ROS (apoROS) signal that controls polarized cell growth, biotic and abiotic defences, and cell to cell signaling, as well as exerting control over the light-dependent regulation of photosynthesis. Critical Issues: Here we re-evaluate the roles of ascorbate in photosynthesis and other processes, addressing the question of how much we really know about the regulation of ascorbate homeostasis and its functions in plants, or how AO is regulated to modulate apoROS signals. Future Directions: The role of microRNAs in the regulation of AO activity in relation to stress perception and signaling must be resolved. Similarly, the molecular characterization of ascorbate transporters and mechanistic links between photosynthetic and respiratory electron transport and ascorbate synthesis/homeostasis are a prerequisite to understanding ascorbate homeostasis and function. Similarly, there is little in vivo evidence for ascorbate functions as an enzyme cofactor.
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Affiliation(s)
- Christine H Foyer
- School of Biosciences, College of Life and Environmental Sciences, University of Birmingham, Edgbaston, United Kingdom
| | - Tina Kyndt
- Department Biotechnology, University of Ghent, Ghent, Belgium
| | - Robert D Hancock
- Cell and Molecular Sciences, The James Hutton Institute, Dundee, United Kingdom
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Wang Z, Wei X, Yang J, Li H, Ma B, Zhang K, Zhang Y, Cheng L, Ma F, Li M. Heterologous expression of the apple hexose transporter MdHT2.2 altered sugar concentration with increasing cell wall invertase activity in tomato fruit. PLANT BIOTECHNOLOGY JOURNAL 2020; 18:540-552. [PMID: 31350935 PMCID: PMC6953210 DOI: 10.1111/pbi.13222] [Citation(s) in RCA: 30] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/09/2019] [Revised: 07/17/2019] [Accepted: 07/19/2019] [Indexed: 05/08/2023]
Abstract
Sugar transporters are necessary to transfer hexose from cell wall spaces into parenchyma cells to boost hexose accumulation to high concentrations in fruit. Here, we have identified an apple hexose transporter (HTs), MdHT2.2, located in the plasma membrane, which is highly expressed in mature fruit. In a yeast system, the MdHT2.2 protein exhibited high 14 C-fructose and 14 C-glucose transport activity. In transgenic tomato heterologously expressing MdHT2.2, the levels of both fructose and glucose increased significantly in mature fruit, with sugar being unloaded via the apoplastic pathway, but the level of sucrose decreased significantly. Analysis of enzyme activity and the expression of genes related to sugar metabolism and transport revealed greatly up-regulated expression of SlLIN5, a key gene encoding cell wall invertase (CWINV), as well as increased CWINV activity in tomatoes transformed with MdHT2.2. Moreover, the levels of fructose, glucose and sucrose recovered nearly to those of the wild type in the sllin5-edited mutant of the MdHT2.2-expressing lines. However, the overexpression of MdHT2.2 decreased hexose levels and increased sucrose levels in mature leaves and young fruit, suggesting that the response pathway for the apoplastic hexose signal differs among tomato tissues. The present study identifies a new HTs in apple that is able to take up fructose and glucose into cells and confirms that the apoplastic hexose levels regulated by HT controls CWINV activity to alter carbohydrate partitioning and sugar content.
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Affiliation(s)
- Zhengyang Wang
- State Key Laboratory of Crop Stress Biology for Arid Areas/College of Horticulture/Shaanxi Key Laboratory of AppleNorthwest A&F UniversityYanglingShaanxiChina
| | - Xiaoyu Wei
- State Key Laboratory of Crop Stress Biology for Arid Areas/College of Horticulture/Shaanxi Key Laboratory of AppleNorthwest A&F UniversityYanglingShaanxiChina
| | - Jingjing Yang
- State Key Laboratory of Crop Stress Biology for Arid Areas/College of Horticulture/Shaanxi Key Laboratory of AppleNorthwest A&F UniversityYanglingShaanxiChina
| | - Huixia Li
- State Key Laboratory of Crop Stress Biology for Arid Areas/College of Horticulture/Shaanxi Key Laboratory of AppleNorthwest A&F UniversityYanglingShaanxiChina
| | - Baiquan Ma
- State Key Laboratory of Crop Stress Biology for Arid Areas/College of Horticulture/Shaanxi Key Laboratory of AppleNorthwest A&F UniversityYanglingShaanxiChina
| | - Kaikai Zhang
- State Key Laboratory of Crop Stress Biology for Arid Areas/College of Horticulture/Shaanxi Key Laboratory of AppleNorthwest A&F UniversityYanglingShaanxiChina
| | - Yanfeng Zhang
- Hybrid Rape Research Center of Shaanxi ProvinceYanglingChina
| | - Lailiang Cheng
- Section of HorticultureSchool of Integrative Plant ScienceCornell UniversityIthacaNYUSA
| | - Fengwang Ma
- State Key Laboratory of Crop Stress Biology for Arid Areas/College of Horticulture/Shaanxi Key Laboratory of AppleNorthwest A&F UniversityYanglingShaanxiChina
| | - Mingjun Li
- State Key Laboratory of Crop Stress Biology for Arid Areas/College of Horticulture/Shaanxi Key Laboratory of AppleNorthwest A&F UniversityYanglingShaanxiChina
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7
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Torcello-Gómez A, Gedi MA, Ibbett R, Nawaz Husain K, Briars R, Gray D. Chloroplast-rich material from the physical fractionation of pea vine (Pisum sativum) postharvest field residue (Haulm). Food Chem 2019; 272:18-25. [PMID: 30309529 DOI: 10.1016/j.foodchem.2018.08.018] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2018] [Revised: 08/02/2018] [Accepted: 08/04/2018] [Indexed: 10/28/2022]
Abstract
An innovative procedure for plant chloroplasts isolation has been proposed, which consists of juice extraction by physical fractionation from plant material and recovery of its chloroplast-rich fraction (CRF) by centrifugation. This simple method has been applied to pea vine haulm subjected to different post-harvest treatments: blanching, storage at different relative humidity values and fermentation. Additionally, freeze storage of the extracted juice was carried out. The macronutrient (total lipids, proteins, ash and carbohydrates) and micronutrient (fatty acids, chlorophylls, β-carotene, α-tocopherol and ascorbic acid) content and composition of the CRF have been determined. The CRF isolated from fresh pea vine haulm is a potential source of essential micronutrients (α-linolenic acid, β-carotene, α-tocopherol) and carbohydrates, whereas the post-harvest treatments trialled have a detrimental effect on the nutritional content. Industrial applications for the recovered nutritionally rich fraction, such as food supplement ingredient or animal feeding, are likely envisaged, while optimising the use of green haulm.
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Affiliation(s)
- Amelia Torcello-Gómez
- Division of Food Sciences, School of Biosciences, University of Nottingham, Sutton Bonington Campus, Loughborough LE12 5RD, United Kingdom.
| | - Mohamed A Gedi
- Division of Food Sciences, School of Biosciences, University of Nottingham, Sutton Bonington Campus, Loughborough LE12 5RD, United Kingdom.
| | - Roger Ibbett
- Division of Food Sciences, School of Biosciences, University of Nottingham, Sutton Bonington Campus, Loughborough LE12 5RD, United Kingdom.
| | - Khatija Nawaz Husain
- Division of Food Sciences, School of Biosciences, University of Nottingham, Sutton Bonington Campus, Loughborough LE12 5RD, United Kingdom.
| | - Rhianna Briars
- Division of Food Sciences, School of Biosciences, University of Nottingham, Sutton Bonington Campus, Loughborough LE12 5RD, United Kingdom.
| | - David Gray
- Division of Food Sciences, School of Biosciences, University of Nottingham, Sutton Bonington Campus, Loughborough LE12 5RD, United Kingdom.
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8
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Smirnoff N. Ascorbic acid metabolism and functions: A comparison of plants and mammals. Free Radic Biol Med 2018; 122:116-129. [PMID: 29567393 PMCID: PMC6191929 DOI: 10.1016/j.freeradbiomed.2018.03.033] [Citation(s) in RCA: 275] [Impact Index Per Article: 45.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/17/2017] [Revised: 03/15/2018] [Accepted: 03/17/2018] [Indexed: 02/07/2023]
Abstract
Ascorbic acid is synthesised by eukaryotes, the known exceptions being primates and some other animal groups which have lost functional gulonolactone oxidase. Prokaryotes do not synthesise ascorbate and do not need an ascorbate supply, so the functions that are essential for mammals and plants are not required or are substituted by other compounds. The ability of ascorbate to donate electrons enables it to act as a free radical scavenger and to reduce higher oxidation states of iron to Fe2+. These reactions are the basis of its biological activity along with the relative stability of the resulting resonance stabilised monodehydroascorbate radical. The importance of these properties is emphasised by the evolution of at least three biosynthetic pathways and production of an ascorbate analogue, erythroascorbate, by fungi. The iron reducing activity of ascorbate maintains the reactive centre Fe2+ of 2-oxoglutarate-dependent dioxygenases (2-ODDs) thus preventing inactivation. These enzymes have diverse functions and, recently, the possibility that ascorbate status in mammals could influence 2-ODDs involved in histone and DNA demethylation thereby influencing stem cell differentiation and cancer has been uncovered. Ascorbate is involved in iron uptake and transport in plants and animals. While the above biochemical functions are shared between mammals and plants, ascorbate peroxidase (APX) is an enzyme family limited to plants and photosynthetic protists. It provides these organisms with increased capacity to remove H2O2 produced by photosynthetic electron transport and photorespiration. The Fe reducing activity of ascorbate enables hydroxyl radical production (pro-oxidant effect) and the reactivity of dehydroascorbate (DHA) and reaction of its degradation products with proteins (dehydroascorbylation and glycation) is potentially damaging. Ascorbate status influences gene expression in plants and mammals but at present there is little evidence that it acts as a specific signalling molecule. It most likely acts indirectly by influencing the redox state of thiols and 2-ODD activity. However, the possibility that dehydroascorbylation is a regulatory post-translational protein modification could be explored.
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Affiliation(s)
- Nicholas Smirnoff
- Biosciences, College of Life and Environmental Sciences, University of Exeter, Geoffrey Pope Building, Stocker Road, Exeter EX4 4QD, UK.
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9
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He C, Zeng S, Teixeira da Silva JA, Yu Z, Tan J, Duan J. Molecular cloning and functional analysis of the phosphomannomutase (PMM) gene from Dendrobium officinale and evidence for the involvement of an abiotic stress response during germination. PROTOPLASMA 2017; 254:1693-1704. [PMID: 27987037 DOI: 10.1007/s00709-016-1044-1] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/15/2016] [Accepted: 11/07/2016] [Indexed: 06/06/2023]
Abstract
Phosphomannomutase (PMM, EC 5.4.2.8) catalyzes the interconversion of mannose-6-phosphate to mannose-1-phosphate, the precursor for the synthesis of GDP-mannose. In this study, the complementary DNA (cDNA) of the Phosphomannomutase (PMM) gene was initially cloned from Dendrobium officinale by RACE method. Transient transform result showed that the DoPMM protein was localized in the cytoplasm. The DoPMM gene was highly expressed in the stems of D. officinale both in vegetative and reproductive developmental stages. The putative promoter was cloned by TAIL-PCR and used for searched cis-elements. Stress-related cis-elements like ABRE, TCA-element, and MBS were found in the promoter regions. The DoPMM gene was up-regulated after treatment with abscisic acid, salicylic acid, cold, polyethylene glycol, and NaCl. The total ascorbic acid (AsA) and polysaccharide content in all of the 35S::DoPMM Arabidopsis thaliana transgenic lines #1, #2, and #5 showed a 40, 39, and 31% increase in AsA and a 77, 22, and 39% increase in polysaccharides, respectively more than wild-type (WT) levels. All three 35S::DoPMM transgenic lines exhibited a higher germination percentage than WT plants when seeded on half-strength MS medium supplemented with 150 mM NaCl or 300 mM mannitol. These results provide genetic evidence for the involvement of PMM genes in the biosynthesis of AsA and polysaccharides and the mediation of PMM genes in abiotic stress tolerance during seed germination in A. thaliana.
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Affiliation(s)
- Chunmei He
- Key Laboratory of South China Agricultural Plant Molecular Analysis and Gene Improvement, South China Botanical Garden, Chinese Academy of Sciences, Guangzhou, 510650, China
| | - Songjun Zeng
- Key Laboratory of South China Agricultural Plant Molecular Analysis and Gene Improvement, South China Botanical Garden, Chinese Academy of Sciences, Guangzhou, 510650, China
| | | | - Zhenming Yu
- Key Laboratory of South China Agricultural Plant Molecular Analysis and Gene Improvement, South China Botanical Garden, Chinese Academy of Sciences, Guangzhou, 510650, China
| | - Jianwen Tan
- Key Laboratory of South China Agricultural Plant Molecular Analysis and Gene Improvement, South China Botanical Garden, Chinese Academy of Sciences, Guangzhou, 510650, China
| | - Jun Duan
- Key Laboratory of South China Agricultural Plant Molecular Analysis and Gene Improvement, South China Botanical Garden, Chinese Academy of Sciences, Guangzhou, 510650, China.
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10
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Villa-Ruano N, Pacheco-Hernández Y, Cruz-Durán R, Lozoya-Gloria E, Betancourt-Jiménez MG. Seasonal variation in phytochemicals and nutraceutical potential of Begonia nelumbiifolia consumed in Puebla, México. JOURNAL OF FOOD SCIENCE AND TECHNOLOGY 2017; 54:1484-1490. [PMID: 28559607 PMCID: PMC5430179 DOI: 10.1007/s13197-017-2576-x] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Revised: 02/16/2017] [Accepted: 02/28/2017] [Indexed: 10/19/2022]
Abstract
Begonia nelumbiifolia is a traditional edible plant consumed and commercialized in the northern highlands of Puebla, México. The present study reports the seasonal variation in proximate analysis as well as organic acids, carotenoids and flavonoids content in both leaves and stalks of this plant. The stalks contained low concentrations of protein (~3%), fiber (~1.5%) and nitrogen free extract (~0.26%) during the time of study. Both organs showed contents of oxalic acid (91-103 mg 100 g-1 FW), ascorbic acid (50-65 mg 100 g-1 FW), lutein (1-2.5 mg 100 g-1 FW), β-carotene (1-3 mg 100 g-1 FW), quercetin (1.3-2.7 mg 100 g-1 DW) and rutin (0.5-1.7 mg 100 g-1 DW). Antioxidant activity against DPPH was observed by the stalk extracts from 30% methanol (IC50, 0.21-0.37 mg L-1), pure methanol (IC50, 0.14-0.21 mg L-1) and hexane: acetone (IC50, 0.77-1.21 mg L-1). In vitro anti-HMG-CoA reductase (IC50, 0.07-0.36 mg L-1) and anti-alpha-glucosidase (IC50, 0.28-0.43 mg L-1) activities were observed in extracts from the edible stalks from pure methanol and 30% methanol. The leaf extracts from 30% methanol inhibited the growth of Pseudomonas syringae pv. tabaci TBR2004 (MIC, 254 µg mL-1), P. syringae pv. tomato DC3000 (MIC, 423 µg mL-1), P. syringae pv. glycinea (MIC, 605 µg mL-1) and Clavibacter michiganensis AB299158 (MIC, 162 µg mL-1). B. nelumbiifolia contained valuable phytochemicals associated to nutraceutical and biological properties. However, the consumption of the fresh stalks must be carefully considered because of the high oxalate content.
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Affiliation(s)
- Nemesio Villa-Ruano
- Universidad de la Sierra Sur. Guillermo Rojas Mijangos S/N, Ciudad Universitaria, Miahuatlán de Porfirio Díaz, CP 70800 Oaxaca Mexico
| | - Yesenia Pacheco-Hernández
- Centro de Investigación en Biotecnología Aplicada-IPN, Ex-Hacienda San Juan Molino, Carretera Estatal Tecuexcomac-Tepetitla Km 1.5, CP 90700 Tepetitla de Lardizabal, Tlaxcala Mexico
| | - Ramiro Cruz-Durán
- Facultad de Ciencias UNAM, Ciudad Universitaria, CP 04510 Delegación Coyoacán, D.F. Mexico
| | - Edmundo Lozoya-Gloria
- Centro de Investigación y de Estudios Avanzados del IPN Unidad Irapuato, Km 9.6 Carretera Irapuato-León, CP 36821 Irapuato, Guanajuato Mexico
| | - Martha G Betancourt-Jiménez
- Centro de Investigación y de Estudios Avanzados del IPN Unidad Irapuato, Km 9.6 Carretera Irapuato-León, CP 36821 Irapuato, Guanajuato Mexico
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Seminario A, Song L, Zulet A, Nguyen HT, González EM, Larrainzar E. Drought Stress Causes a Reduction in the Biosynthesis of Ascorbic Acid in Soybean Plants. FRONTIERS IN PLANT SCIENCE 2017; 8:1042. [PMID: 28663755 PMCID: PMC5471321 DOI: 10.3389/fpls.2017.01042] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/03/2017] [Accepted: 05/30/2017] [Indexed: 05/03/2023]
Abstract
Drought provokes a number of physiological changes in plants including oxidative damage. Ascorbic acid (AsA), also known as vitamin C, is one of the most abundant water-soluble antioxidant compound present in plant tissues. However, little is known on the regulation of AsA biosynthesis under drought stress conditions. In the current work we analyze the effects of water deficit on the biosynthesis of AsA by measuring its content, in vivo biosynthesis and the expression level of genes in the Smirnoff-Wheeler pathway in one of the major legume crop, soybean (Glycine max L. Merr). Since the pathway has not been described in legumes, we first searched for the putative orthologous genes in the soybean genome. We observed a significant genetic redundancy, with multiple genes encoding each step in the pathway. Based on RNA-seq analysis, expression of the complete pathway was detected not only in leaves but also in root tissue. Putative paralogous genes presented differential expression patterns in response to drought, suggesting the existence of functional specialization mechanisms. We found a correlation between the levels of AsA and GalLDH biosynthetic rates in leaves of drought-stressed soybean plants. However, the levels of GalLDH transcripts did not show significant differences under water deficit conditions. Among the other known regulators of the pathway, only the expression of VTC1 genes correlated with the observed decline in AsA in leaves.
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Affiliation(s)
- Amaia Seminario
- Department of Environmental Sciences, Universidad Pública de NavarraPamplona, Spain
| | - Li Song
- Division of Plant Science and National Center for Soybean Biotechnology, University of Missouri, ColumbiaMO, United States
| | - Amaia Zulet
- Department of Environmental Sciences, Universidad Pública de NavarraPamplona, Spain
| | - Henry T. Nguyen
- Division of Plant Science and National Center for Soybean Biotechnology, University of Missouri, ColumbiaMO, United States
| | - Esther M. González
- Department of Environmental Sciences, Universidad Pública de NavarraPamplona, Spain
- *Correspondence: Estíbaliz Larrainzar, Esther M. González,
| | - Estíbaliz Larrainzar
- Department of Environmental Sciences, Universidad Pública de NavarraPamplona, Spain
- *Correspondence: Estíbaliz Larrainzar, Esther M. González,
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Fisunov GY, Garanina IA, Evsyutina DV, Semashko TA, Nikitina AS, Govorun VM. Reconstruction of Transcription Control Networks in Mollicutes by High-Throughput Identification of Promoters. Front Microbiol 2016; 7:1977. [PMID: 27999573 PMCID: PMC5138195 DOI: 10.3389/fmicb.2016.01977] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2016] [Accepted: 11/25/2016] [Indexed: 01/05/2023] Open
Abstract
Bacteria of the class Mollicutes have significantly reduced genomes and gene expression control systems. They are also efficient pathogens that can colonize a broad range of hosts including plants and animals. Despite their simplicity, Mollicutes demonstrate complex transcriptional responses to various conditions, which contradicts their reduction in gene expression regulation mechanisms. We analyzed the conservation and distribution of transcription regulators across the 50 Mollicutes species. The majority of the transcription factors regulate transport and metabolism, and there are four transcription factors that demonstrate significant conservation across the analyzed bacteria. These factors include repressors of chaperone HrcA, cell cycle regulator MraZ and two regulators with unclear function from the WhiA and YebC/PmpR families. We then used three representative species of the major clades of Mollicutes (Acholeplasma laidlawii, Spiroplasma melliferum, and Mycoplasma gallisepticum) to perform promoter mapping and activity quantitation. We revealed that Mollicutes evolved towards a promoter architecture simplification that correlates with a diminishing role of transcription regulation and an increase in transcriptional noise. Using the identified operons structure and a comparative genomics approach, we reconstructed the transcription control networks for these three species. The organization of the networks reflects the adaptation of bacteria to specific conditions and hosts.
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Affiliation(s)
- Gleb Y Fisunov
- Federal Research and Clinical Centre of Physical-Chemical Medicine Moscow, Russia
| | - Irina A Garanina
- Federal Research and Clinical Centre of Physical-Chemical MedicineMoscow, Russia; Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, the Russian Academy of SciencesMoscow, Russia
| | - Daria V Evsyutina
- Federal Research and Clinical Centre of Physical-Chemical Medicine Moscow, Russia
| | - Tatiana A Semashko
- Federal Research and Clinical Centre of Physical-Chemical Medicine Moscow, Russia
| | - Anastasia S Nikitina
- Federal Research and Clinical Centre of Physical-Chemical MedicineMoscow, Russia; Moscow Institute of Physics and TechnologyMoscow, Russia
| | - Vadim M Govorun
- Federal Research and Clinical Centre of Physical-Chemical MedicineMoscow, Russia; Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, the Russian Academy of SciencesMoscow, Russia; Moscow Institute of Physics and TechnologyMoscow, Russia
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Transcriptional reprogramming of genes related to ascorbate and glutathione biosynthesis, turnover and translocation in aphid-challenged maize seedlings. BIOCHEM SYST ECOL 2016. [DOI: 10.1016/j.bse.2016.10.009] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
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14
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Zhang X, Yu HJ, Zhang XM, Yang XY, Zhao WC, Li Q, Jiang WJ. Effect of nitrogen deficiency on ascorbic acid biosynthesis and recycling pathway in cucumber seedlings. PLANT PHYSIOLOGY AND BIOCHEMISTRY : PPB 2016; 108:222-230. [PMID: 27459340 DOI: 10.1016/j.plaphy.2016.07.012] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/06/2016] [Revised: 06/29/2016] [Accepted: 07/09/2016] [Indexed: 05/27/2023]
Abstract
L-Ascorbic acid (AsA, ascorbate) is one of the most abundant natural antioxidants, and it is an important factor in the nutritional quality of cucumber. In this work, key enzymes involved in the ascorbic acid biosynthesis and recycling pathway in cucumber seedlings under nitrogen deficiency were investigated at the levels of transcription and enzyme activity. The activities of myo-inositol oxygenase (MIOX) and transcript levels of MIOXs increased dramatically, while the activities of ascorbate oxidase (AO) and glutathione reductase (GR) and transcript levels of AOs and GR2 decreased significantly in N-limited leaves, as did the ascorbate concentration, in nitrogen-deficient cucumber seedlings. The activities of other enzymes and transcript levels of other genes involved in the ascorbate recycling pathway and ascorbate synthesis pathways decreased or remained unchanged under nitrogen deficiency. These results indicate that nitrogen deficiency induced genes involved in the ascorbate-glutathione recycling and myo-inositol pathway in cucumber leaves. Thus, the AO, GR and MIOX involved in the pathways might play roles in AsA accumulation.
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Affiliation(s)
- Xue Zhang
- Key Laboratory of Horticultural Crops Genetic Improvement (Ministry of Agriculture), Institute of Vegetables and Flowers, Chinese Academy of Agricultural Sciences, Beijing 100081, China
| | - Hong Jun Yu
- Key Laboratory of Horticultural Crops Genetic Improvement (Ministry of Agriculture), Institute of Vegetables and Flowers, Chinese Academy of Agricultural Sciences, Beijing 100081, China
| | - Xiao Meng Zhang
- Key Laboratory of Horticultural Crops Genetic Improvement (Ministry of Agriculture), Institute of Vegetables and Flowers, Chinese Academy of Agricultural Sciences, Beijing 100081, China
| | - Xue Yong Yang
- Key Laboratory of Horticultural Crops Genetic Improvement (Ministry of Agriculture), Institute of Vegetables and Flowers, Chinese Academy of Agricultural Sciences, Beijing 100081, China
| | - Wen Chao Zhao
- Beijing Key Laboratory for Agriculture Application and New Technology, Plant Science and Technology College, Beijing University of Agriculture, Beijing 102206, China
| | - Qiang Li
- Key Laboratory of Horticultural Crops Genetic Improvement (Ministry of Agriculture), Institute of Vegetables and Flowers, Chinese Academy of Agricultural Sciences, Beijing 100081, China.
| | - Wei Jie Jiang
- Key Laboratory of Horticultural Crops Genetic Improvement (Ministry of Agriculture), Institute of Vegetables and Flowers, Chinese Academy of Agricultural Sciences, Beijing 100081, China; Xinjiang Agricultural University, Urumqi 830052, Xinjiang, China.
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Valcarcel J, Reilly K, Gaffney M, O'Brien NM. Levels of potential bioactive compounds including carotenoids, vitamin C and phenolic compounds, and expression of their cognate biosynthetic genes vary significantly in different varieties of potato (Solanum tuberosum L.) grown under uniform cultural conditions. JOURNAL OF THE SCIENCE OF FOOD AND AGRICULTURE 2016; 96:1018-1026. [PMID: 25821013 DOI: 10.1002/jsfa.7189] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/30/2014] [Accepted: 03/23/2015] [Indexed: 06/04/2023]
Abstract
BACKGROUND In addition to their high carbohydrate content, potatoes are also an important dietary source of vitamin C and bioactive secondary metabolites, including phenolic compounds and carotenoids, which have been suggested to play a role in human health. The expression of genes encoding key enzymes involved in the synthesis of these compounds was assessed by reverse transcription-quantitative polymerase chain reaction and compared to the accumulation of the corresponding product in seven potato varieties showing contrasting levels of metabolite accumulation. RESULTS Strong positive correlations were found between phenolic content in the flesh of tubers and transcript levels of phenylalanine ammonia lyase (PAL) and chalcone synthase (CHS) genes. The expression of PAL and CHS was also related to that of AN1, a transcription factor involved in the synthesis of anthocyanins, suggesting that these genes are regulated in a coordinated manner. No clear relationship was found between transcript levels of phytoene synthase (PSY) or L-galactono-1,4-lactone dehydrogenase (GLDH) genes and total carotenoid or vitamin C accumulation, respectively. CONCLUSION Data indicate that levels of total phenolic and flavonoid compounds in potato are controlled primarily by PAL and CHS gene expression. Transcript levels of PSY and GLDH did not control accumulation of carotenoids or vitamin C.
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Affiliation(s)
- Jesus Valcarcel
- Teagasc, Horticulture Development Department, Ashtown Food Research Centre, Dublin 15, Ireland
- School of Food and Nutritional Sciences, University College Cork, Cork, Ireland
| | - Kim Reilly
- Teagasc, Horticulture Development Department, Ashtown Food Research Centre, Dublin 15, Ireland
| | - Michael Gaffney
- Teagasc, Horticulture Development Department, Ashtown Food Research Centre, Dublin 15, Ireland
| | - Nora M O'Brien
- School of Food and Nutritional Sciences, University College Cork, Cork, Ireland
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Lovat C, Nassar AM, Kubow S, Li XQ, Donnelly DJ. Metabolic Biosynthesis of Potato (Solanum tuberosuml.) Antioxidants and Implications for Human Health. Crit Rev Food Sci Nutr 2015; 56:2278-303. [DOI: 10.1080/10408398.2013.830208] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
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17
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Venkatesh J, Park SW. Role of L-ascorbate in alleviating abiotic stresses in crop plants. BOTANICAL STUDIES 2014; 55:38. [PMID: 28510969 PMCID: PMC5432849 DOI: 10.1186/1999-3110-55-38] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/08/2012] [Accepted: 12/16/2013] [Indexed: 05/21/2023]
Abstract
L-ascorbic acid (vitamin C) is a major antioxidant in plants and plays a significant role in mitigation of excessive cellular reactive oxygen species activities caused by number of abiotic stresses. Plant ascorbate levels change differentially in response to varying environmental stress conditions, depending on the degree of stress and species sensitivity. Successful modulation of ascorbate biosynthesis through genetic manipulation of genes involved in biosynthesis, catabolism and recycling of ascorbate has been achieved. Recently, role of ascorbate in alleviating number of abiotic stresses has been highlighted in crop plants. In this article, we discuss the current understanding of ascorbate biosynthesis and its antioxidant role in order to increase our comprehension of how ascorbate helps plants to counteract or cope with various abiotic stresses.
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Affiliation(s)
- Jelli Venkatesh
- Department of Molecular Biotechnology, Konkuk University, 1, Hwayang-dong, Seoul, Gwangjin-gu South Korea
| | - Se Won Park
- Department of Molecular Biotechnology, Konkuk University, 1, Hwayang-dong, Seoul, Gwangjin-gu South Korea
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18
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Gallie DR. L-ascorbic Acid: a multifunctional molecule supporting plant growth and development. SCIENTIFICA 2013; 2013:795964. [PMID: 24278786 PMCID: PMC3820358 DOI: 10.1155/2013/795964] [Citation(s) in RCA: 118] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/16/2012] [Accepted: 10/02/2012] [Indexed: 05/19/2023]
Abstract
L-Ascorbic acid (vitamin C) is as essential to plants as it is to animals. Ascorbic acid functions as a major redox buffer and as a cofactor for enzymes involved in regulating photosynthesis, hormone biosynthesis, and regenerating other antioxidants. Ascorbic acid regulates cell division and growth and is involved in signal transduction. In contrast to the single pathway responsible for ascorbic acid biosynthesis in animals, plants use multiple pathways to synthesize ascorbic acid, perhaps reflecting the importance of this molecule to plant health. Given the importance of ascorbic acid to human nutrition, several technologies have been developed to increase the ascorbic acid content of plants through the manipulation of biosynthetic or recycling pathways. This paper provides an overview of these approaches as well as the consequences that changes in ascorbic acid content have on plant growth and function. Discussed is the capacity of plants to tolerate changes in ascorbic acid content. The many functions that ascorbic acid serves in plants, however, will require highly targeted approaches to improve their nutritional quality without compromising their health.
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Affiliation(s)
- Daniel R. Gallie
- Department of Biochemistry, University of California, Riverside, CA 92521-0129, USA
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Gest N, Gautier H, Stevens R. Ascorbate as seen through plant evolution: the rise of a successful molecule? JOURNAL OF EXPERIMENTAL BOTANY 2013; 64:33-53. [PMID: 23109712 DOI: 10.1093/jxb/ers297] [Citation(s) in RCA: 128] [Impact Index Per Article: 11.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/18/2023]
Abstract
Ascorbate is a widespread and efficient antioxidant that has multiple functions in plants, traditionally associated with the reactions of photosynthesis. This review aims to look at ascorbate from an evolutionary perspective. Cyanobacteria, algae, and bryophytes contain lower concentrations of ascorbate than higher plants, where the molecule accumulates in high concentrations in both photosynthetic and non-photosynthetic organs and tissues. This increase in ascorbate concentration is paralleled by an increase in the number of isoforms of ascorbate peroxidase and the ascorbate regenerating enzymes mono- and dehydroascorbate reductase. One way of understanding the rise in ascorbate concentrations is to consider ascorbate as a molecule among others that has been subject to selection pressures during evolution, due to its cost or benefit for the cell and the organism. Ascorbate has a low cost in terms of synthesis and toxicity, and its benefits include protection of the glutathione pool and proper functioning of a range of enzymes. The hypothesis presented here is that these features would have favoured increasing roles for the molecule in the development and growth of multicellular organisms. This review then focuses on this diversity of roles for ascorbate in both photosynthetic and non-photosynthetic tissues of higher plants, including fruits and seeds, as well as further functions the molecule may possess by looking at other species. The review also highlights one of the trade-offs of domestication, which has often reduced or diluted ascorbate content in the quest for increased fruit growth and yield, with unknown consequences for the corresponding functional diversity, particularly in terms of stress resistance and adaptive responses to the environment.
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Affiliation(s)
- Noé Gest
- INRA, UR1052, Génétique et amélioration des fruits et légumes, Domaine St Maurice, 84143 Montfavet, France
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20
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Gallie DR. L-ascorbic Acid: a multifunctional molecule supporting plant growth and development. SCIENTIFICA 2013; 2013:795964. [PMID: 24278786 DOI: 10.1155/scientifica/2013/795964] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Subscribe] [Scholar Register] [Received: 08/16/2012] [Accepted: 10/02/2012] [Indexed: 05/21/2023]
Abstract
L-Ascorbic acid (vitamin C) is as essential to plants as it is to animals. Ascorbic acid functions as a major redox buffer and as a cofactor for enzymes involved in regulating photosynthesis, hormone biosynthesis, and regenerating other antioxidants. Ascorbic acid regulates cell division and growth and is involved in signal transduction. In contrast to the single pathway responsible for ascorbic acid biosynthesis in animals, plants use multiple pathways to synthesize ascorbic acid, perhaps reflecting the importance of this molecule to plant health. Given the importance of ascorbic acid to human nutrition, several technologies have been developed to increase the ascorbic acid content of plants through the manipulation of biosynthetic or recycling pathways. This paper provides an overview of these approaches as well as the consequences that changes in ascorbic acid content have on plant growth and function. Discussed is the capacity of plants to tolerate changes in ascorbic acid content. The many functions that ascorbic acid serves in plants, however, will require highly targeted approaches to improve their nutritional quality without compromising their health.
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Affiliation(s)
- Daniel R Gallie
- Department of Biochemistry, University of California, Riverside, CA 92521-0129, USA
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Mellidou I, Keulemans J, Kanellis AK, Davey MW. Regulation of fruit ascorbic acid concentrations during ripening in high and low vitamin C tomato cultivars. BMC PLANT BIOLOGY 2012; 12:239. [PMID: 23245200 PMCID: PMC3548725 DOI: 10.1186/1471-2229-12-239] [Citation(s) in RCA: 59] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/17/2012] [Accepted: 12/12/2012] [Indexed: 05/20/2023]
Abstract
BACKGROUND To gain insight into the regulation of fruit ascorbic acid (AsA) pool in tomatoes, a combination of metabolite analyses, non-labelled and radiolabelled substrate feeding experiments, enzyme activity measurements and gene expression studies were carried out in fruits of the 'low-' and 'high-AsA' tomato cultivars 'Ailsa Craig' and 'Santorini' respectively. RESULTS The two cultivars exhibited different profiles of total AsA (totAsA, AsA + dehydroascorbate) and AsA accumulation during ripening, but both displayed a characteristic peak in concentrations at the breaker stage. Substrate feeding experiments demonstrated that the L-galactose pathway is the main AsA biosynthetic route in tomato fruits, but that substrates from alternative pathways can increase the AsA pool at specific developmental stages. In addition, we show that young fruits display a higher AsA biosynthetic capacity than mature ones, but this does not lead to higher AsA concentrations due to either enhanced rates of AsA breakdown ('Ailsa Craig') or decreased rates of AsA recycling ('Santorini'), depending on the cultivar. In the later stages of ripening, differences in fruit totAsA-AsA concentrations of the two cultivars can be explained by differences in the rate of AsA recycling activities. Analysis of the expression of AsA metabolic genes showed that only the expression of one orthologue of GDP-L-galactose phosphorylase (SlGGP1), and of two monodehydroascorbate reductases (SlMDHAR1 and SlMDHAR3) correlated with the changes in fruit totAsA-AsA concentrations during fruit ripening in 'Ailsa Craig', and that only the expression of SlGGP1 was linked to the high AsA concentrations found in red ripe 'Santorini' fruits. CONCLUSIONS Results indicate that 'Ailsa Craig' and 'Santorini' use complementary mechanisms to maintain the fruit AsA pool. In the low-AsA cultivar ('Ailsa Craig'), alternative routes of AsA biosynthesis may supplement biosynthesis via L-galactose, while in the high-AsA cultivar ('Santorini'), enhanced AsA recycling activities appear to be responsible for AsA accumulation in the later stages of ripening. Gene expression studies indicate that expression of SlGGP1 and two orthologues of SlMDHAR are closely correlated with totAsA-AsA concentrations during ripening and are potentially good candidates for marker development for breeding and selection.
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Affiliation(s)
- Ifigeneia Mellidou
- Laboratory for Fruit Breeding and Biotechnology, Department of Biosystems, Faculty of Bioscience Engineering, Katholieke Universiteit Leuven, B-3001, Heverlee, Belgium
| | - Johan Keulemans
- Laboratory for Fruit Breeding and Biotechnology, Department of Biosystems, Faculty of Bioscience Engineering, Katholieke Universiteit Leuven, B-3001, Heverlee, Belgium
| | - Angelos K Kanellis
- Group of Biotechnology of Pharmaceutical Plants. Laboratory of Pharmacognosy, Department of Pharmaceutical Sciences, Aristotle University of Thessaloniki, 541 24, Thessaloniki, Greece
| | - Mark W Davey
- Laboratory for Fruit Breeding and Biotechnology, Department of Biosystems, Faculty of Bioscience Engineering, Katholieke Universiteit Leuven, B-3001, Heverlee, Belgium
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Mellidou I, Chagné D, Laing WA, Keulemans J, Davey MW. Allelic variation in paralogs of GDP-L-galactose phosphorylase is a major determinant of vitamin C concentrations in apple fruit. PLANT PHYSIOLOGY 2012; 160:1613-29. [PMID: 23001142 PMCID: PMC3490610 DOI: 10.1104/pp.112.203786] [Citation(s) in RCA: 55] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/17/2012] [Accepted: 09/19/2012] [Indexed: 05/18/2023]
Abstract
To identify the genetic factors underlying the regulation of fruit vitamin C (L-ascorbic acid [AsA]) concentrations, quantitative trait loci (QTL) studies were carried out in an F1 progeny derived from a cross between the apple (Malus × domestica) cultivars Telamon and Braeburn over three years. QTL were identified for AsA, glutathione, total antioxidant activity in both flesh and skin tissues, and various quality traits, including flesh browning. Four regions on chromosomes 10, 11, 16, and 17 contained stable fruit AsA-QTL clusters. Mapping of AsA metabolic genes identified colocations between orthologs of GDP-L-galactose phosphorylase (GGP), dehydroascorbate reductase (DHAR), and nucleobase-ascorbate transporter within these QTL clusters. Of particular interest are the three paralogs of MdGGP, which all colocated within AsA-QTL clusters. Allelic variants of MdGGP1 and MdGGP3 derived from the cultivar Braeburn parent were also consistently associated with higher fruit total AsA concentrations both within the mapping population (up to 10-fold) and across a range of commercial apple germplasm (up to 6-fold). Striking differences in the expression of the cv Braeburn MdGGP1 allele between fruit from high- and low-AsA genotypes clearly indicate a key role for MdGGP1 in the regulation of fruit AsA concentrations, and this MdGGP allele-specific single-nucleotide polymorphism marker represents an excellent candidate for directed breeding for enhanced fruit AsA concentrations. Interestingly, colocations were also found between MdDHAR3-3 and a stable QTL for browning in the cv Telamon parent, highlighting links between the redox status of the AsA pool and susceptibility to flesh browning.
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Affiliation(s)
- Ifigeneia Mellidou
- Laboratory for Fruit Breeding and Biotechnology, Department Biosystems, Faculty of Bioscience Engineering, Katholieke Universiteit Leuven, B–3001 Heverlee, Belgium (I.M., J.K., M.W.D.); New Zealand Institute for Plant and Food Research Limited, Palmerston North Research Centre, Palmerston North 4442, New Zealand (D.C.); and New Zealand Institute for Plant and Food Research Limited, Mount Albert Research Centre, Auckland 1142, New Zealand (W.A.L.)
| | - David Chagné
- Laboratory for Fruit Breeding and Biotechnology, Department Biosystems, Faculty of Bioscience Engineering, Katholieke Universiteit Leuven, B–3001 Heverlee, Belgium (I.M., J.K., M.W.D.); New Zealand Institute for Plant and Food Research Limited, Palmerston North Research Centre, Palmerston North 4442, New Zealand (D.C.); and New Zealand Institute for Plant and Food Research Limited, Mount Albert Research Centre, Auckland 1142, New Zealand (W.A.L.)
| | - William A. Laing
- Laboratory for Fruit Breeding and Biotechnology, Department Biosystems, Faculty of Bioscience Engineering, Katholieke Universiteit Leuven, B–3001 Heverlee, Belgium (I.M., J.K., M.W.D.); New Zealand Institute for Plant and Food Research Limited, Palmerston North Research Centre, Palmerston North 4442, New Zealand (D.C.); and New Zealand Institute for Plant and Food Research Limited, Mount Albert Research Centre, Auckland 1142, New Zealand (W.A.L.)
| | - Johan Keulemans
- Laboratory for Fruit Breeding and Biotechnology, Department Biosystems, Faculty of Bioscience Engineering, Katholieke Universiteit Leuven, B–3001 Heverlee, Belgium (I.M., J.K., M.W.D.); New Zealand Institute for Plant and Food Research Limited, Palmerston North Research Centre, Palmerston North 4442, New Zealand (D.C.); and New Zealand Institute for Plant and Food Research Limited, Mount Albert Research Centre, Auckland 1142, New Zealand (W.A.L.)
| | - Mark W. Davey
- Laboratory for Fruit Breeding and Biotechnology, Department Biosystems, Faculty of Bioscience Engineering, Katholieke Universiteit Leuven, B–3001 Heverlee, Belgium (I.M., J.K., M.W.D.); New Zealand Institute for Plant and Food Research Limited, Palmerston North Research Centre, Palmerston North 4442, New Zealand (D.C.); and New Zealand Institute for Plant and Food Research Limited, Mount Albert Research Centre, Auckland 1142, New Zealand (W.A.L.)
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Cronje C, George GM, Fernie AR, Bekker J, Kossmann J, Bauer R. Manipulation of L-ascorbic acid biosynthesis pathways in Solanum lycopersicum: elevated GDP-mannose pyrophosphorylase activity enhances L-ascorbate levels in red fruit. PLANTA 2012; 235:553-64. [PMID: 21979413 DOI: 10.1007/s00425-011-1525-6] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/06/2011] [Accepted: 09/12/2011] [Indexed: 05/21/2023]
Abstract
Ascorbate (AsA) plays a fundamental role in redox homeostasis in plants and animals, primarily by scavenging reactive oxygen species. Three genes, representing diverse steps putatively involved in plant AsA biosynthesis pathways, were cloned and independently expressed in Solanum lycopersicum (tomato) under the control of the CaMV 35S promoter. Yeast-derived GDP-mannose pyrophosphorylase (GMPase) and arabinono-1,4-lactone oxidase (ALO), as well as myo-inositol oxygenase 2 (MIOX2) from Arabidopsis thaliana, were targeted. Increases in GMPase activity were concomitant with increased AsA levels of up to 70% in leaves, 50% in green fruit, and 35% in red fruit. Expression of ALO significantly pulled biosynthetic flux towards AsA in leaves and green fruit by up to 54 and 25%, respectively. Changes in AsA content in plants transcribing the MIOX2 gene were inconsistent in different tissue. On the other hand, MIOX activity was strongly correlated with cell wall uronic acid levels, suggesting that MIOX may be a useful tool for the manipulation of cell wall composition. In conclusion, the Smirnoff-Wheeler pathway showed great promise as a target for biotechnological manipulation of ascorbate levels in tomato.
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Affiliation(s)
- Christelle Cronje
- Genetics Department, Institute for Plant Biotechnology, Stellenbosch University, Private Bag X1, Matieland 7602, South Africa
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Cronje C, George GM, Fernie AR, Bekker J, Kossmann J, Bauer R. Manipulation of L-ascorbic acid biosynthesis pathways in Solanum lycopersicum: elevated GDP-mannose pyrophosphorylase activity enhances L-ascorbate levels in red fruit. PLANTA 2012. [PMID: 21979413 DOI: 10.1007/s00425-011-1525-1526] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 05/08/2023]
Abstract
Ascorbate (AsA) plays a fundamental role in redox homeostasis in plants and animals, primarily by scavenging reactive oxygen species. Three genes, representing diverse steps putatively involved in plant AsA biosynthesis pathways, were cloned and independently expressed in Solanum lycopersicum (tomato) under the control of the CaMV 35S promoter. Yeast-derived GDP-mannose pyrophosphorylase (GMPase) and arabinono-1,4-lactone oxidase (ALO), as well as myo-inositol oxygenase 2 (MIOX2) from Arabidopsis thaliana, were targeted. Increases in GMPase activity were concomitant with increased AsA levels of up to 70% in leaves, 50% in green fruit, and 35% in red fruit. Expression of ALO significantly pulled biosynthetic flux towards AsA in leaves and green fruit by up to 54 and 25%, respectively. Changes in AsA content in plants transcribing the MIOX2 gene were inconsistent in different tissue. On the other hand, MIOX activity was strongly correlated with cell wall uronic acid levels, suggesting that MIOX may be a useful tool for the manipulation of cell wall composition. In conclusion, the Smirnoff-Wheeler pathway showed great promise as a target for biotechnological manipulation of ascorbate levels in tomato.
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Affiliation(s)
- Christelle Cronje
- Genetics Department, Institute for Plant Biotechnology, Stellenbosch University, Private Bag X1, Matieland 7602, South Africa
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Massot C, Stevens R, Génard M, Longuenesse JJ, Gautier H. Light affects ascorbate content and ascorbate-related gene expression in tomato leaves more than in fruits. PLANTA 2012; 235:153-63. [PMID: 21861113 DOI: 10.1007/s00425-011-1493-x] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/01/2011] [Accepted: 07/14/2011] [Indexed: 05/03/2023]
Abstract
Little is known about the light regulation of vitamin C synthesis in fruits. In contrast, previous studies in leaves revealed that VTC2 (coding for GDP-L: -galactose phosphorylase) was one of the key genes up-regulated by light in leaves. Our objective was to determine how the expression of ascorbate (AsA) synthesis genes in tomato (Solanum lycopersicum) was modified according to light irradiance in both leaves and fruits. Seven days of shading strongly decreased total ascorbate (reduced and oxidized form) content in leaves (50%) and to a lesser extent in fruits (10%). Among the last six steps of AsA biosynthesis, only two genes, VTC2 and GPP1 (one of the two unigenes coding for L: -galactose-1-P phosphatase in tomato), were down-regulated by long-term shading in red ripe fruits, compared to seven genes regulated in leaves. This underlines that light affects AsA-related gene expression more in leaves than in ripening fruits. Moreover, this study reveals strong daily changes in transcript levels of enzymes of the AsA biosynthetic pathway in leaves (11 of the 12 studied genes showed significant changes in their expression pattern). Among those genes, we found that diurnal variation in transcript levels of VTC2 and GME1 correlated to leaf AsA content measured 8 h later. This study provides a new hypothesis on the role of GME1 in addition to VTC2 in light-regulated AsA biosynthesis.
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Affiliation(s)
- Capucine Massot
- INRA UR 1115 Plantes et Systèmes de Culture Horticoles, Domaine St Paul, Site Agroparc, 84914, Avignon, France
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Li M, Ma F, Liang D, Li J, Wang Y. Ascorbate biosynthesis during early fruit development is the main reason for its accumulation in kiwi. PLoS One 2010; 5:e14281. [PMID: 21151561 PMCID: PMC3000333 DOI: 10.1371/journal.pone.0014281] [Citation(s) in RCA: 59] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2010] [Accepted: 11/14/2010] [Indexed: 12/24/2022] Open
Abstract
BACKGROUND Ascorbic acid (AsA) is a unique antioxidant as well as an enzyme cofactor. Although it has multiple roles in plants, it is unclear how its accumulation is controlled at the expression level, especially in sink tissues. Kiwifruit (Actinidia) is well-known for its high ascorbate content. Our objective was to determine whether AsA accumulates in the fruits primarily through biosynthesis or because it is imported from the foliage. METHODOLOGY/PRINCIPAL FINDINGS We systematically investigated AsA levels, biosynthetic capacity, and mRNA expression of genes involved in AsA biosynthesis in kiwi (A. deliciosa cv. Qinmei). Recycling and AsA localization were also monitored during fruit development and among different tissue types. Over time, the amount of AsA, with its capacity for higher biosynthesis and lower recycling, peaked at 30 days after anthesis (DAA), and then decreased markedly up to 60 DAA before declining more slowly. Expression of key genes showed similar patterns of change, except for L-galactono-1,4-lactone dehydrogenase and L-galactose-1-phosphate phosphatase (GPP). However, GPP had good correlation with the rate of AsA accumulation. The expression of these genes could be detected in phloem of stem as well as petiole of leaf and fruit. Additionally, fruit petioles had greater ascorbate amounts, although that was the site of lowest expression by most genes. Fruit microtubule tissues also had higher AsA. However, exogenous applications of AsA to those petioles did not lead to its transport into fruits, and distribution of ascorbate was cell-specific in the fruits, with more accumulation occurring in larger cells. CONCLUSIONS These results suggest that AsA biosynthesis in kiwi during early fruit development is the main reason for its accumulation in the fruits. We also postulate here that GPP is a good candidate for regulating AsA biosynthesis whereas GDP-L-galactose-1-phosphate phosphorylase is not.
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Affiliation(s)
- Mingjun Li
- College of Horticulture, Northwest A&F University, Yangling, China
| | - Fengwang Ma
- College of Horticulture, Northwest A&F University, Yangling, China
| | - Dong Liang
- College of Horticulture, Northwest A&F University, Yangling, China
| | - Juan Li
- College of Horticulture, Northwest A&F University, Yangling, China
| | - Yanlei Wang
- College of Horticulture, Northwest A&F University, Yangling, China
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Cho WK, Chen XY, Rim Y, Chu H, Kim S, Kim SW, Park ZY, Kim JY. Proteome study of the phloem sap of pumpkin using multidimensional protein identification technology. JOURNAL OF PLANT PHYSIOLOGY 2010; 167:771-778. [PMID: 20138393 DOI: 10.1016/j.jplph.2010.01.004] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/10/2009] [Revised: 01/11/2010] [Accepted: 01/11/2010] [Indexed: 05/26/2023]
Abstract
The phloem is the major transport route for both small substances and large molecules, such as proteins and RNAs, from their sources to sink tissues. To investigate the proteins present in pumpkin phloem sap, proteome analysis using multidimensional protein identification technology was carried out. Pumpkin phloem peptides obtained by liquid chromatography/mass spectrometry/mass spectrometry were searched against pumpkin protein data derived from the National Center for Biotechnology Information. A total of 47 pumpkin phloem proteins were identified. The identified proteins mainly corresponded to enzymes involved in gibberellin biosynthesis, antioxidation processes, or defense mechanisms. Interestingly, seven enzymes required for gibberellin biosynthesis were identified for the first time by this proteomics approach. In summary, the new phloem proteins identified in this study provide strong evidence for stress and defense signaling and new insights regarding the role of gibberellin in the developmental programming of higher plants through the phloem.
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Affiliation(s)
- Won Kyong Cho
- Division of Applied Life Science (BK21 Program), Environmental Biotechnology National Core Research Center, Plant Molecular Biology and Biotechnology Research Center, Gyeongsang National University, Jinju 660-701, Republic of Korea
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Herschbach C, Scheerer U, Rennenberg H. Redox states of glutathione and ascorbate in root tips of poplar (Populus tremula X P. alba) depend on phloem transport from the shoot to the roots. JOURNAL OF EXPERIMENTAL BOTANY 2010; 61:1065-74. [PMID: 20022923 PMCID: PMC2826650 DOI: 10.1093/jxb/erp371] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/04/2023]
Abstract
Glutathione (GSH) and ascorbate (ASC) are important antioxidants that are involved in stress defence and cell proliferation of meristematic root cells. In principle, synthesis of ASC and GSH in the roots as well as ASC and GSH transport from the shoot to the roots by phloem mass flow is possible. However, it is not yet known whether the ASC and/or the GSH level in roots depends on the supply from the shoot. This was analysed by feeding mature leaves with [(14)C]ASC or [(35)S]GSH and subsequent detection of the radiolabel in different root fractions. Quantitative dependency of root ASC and GSH on shoot-derived ASC and GSH was investigated with poplar (Populus tremula X P. alba) trees interrupted in phloem transport. [(35)S]GSH is transported from mature leaves to the root tips, but is withdrawn from the phloem along the entire transport path. When phloem transport was interrupted, the GSH content in root tips halved within 3 d. [(14)C]ASC is also transported from mature leaves to the root tips but, in contrast to GSH, ASC is not removed from the phloem along the transport path. Accordingly, ASC accumulates in root tips. Interruption of phloem transport disturbed the level and the ASC redox state within the entire root system. Diminished total ASC levels were attributed mainly to a decline of dehydroascorbate (DHA). As the redox state of ASC is of particular significance for root growth and development, it is concluded that phloem transport of ASC may constitute a shoot to root signal to coordinate growth and development at the whole plant level.
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Affiliation(s)
- Cornelia Herschbach
- Albert-Ludwigs-University Freiburg, Institute of Forest Botany and Tree Physiology, Chair of Tree Physiology, Georges-Köhler-Allee 053/054, D-79110 Freiburg, Germany.
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29
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Yang YH, Song E, Park SH, Kim JN, Lee K, Kim E, Kim YG, Kim BG. Loss of phosphomannomutase activity enhances actinorhodin production in Streptomyces coelicolor. Appl Microbiol Biotechnol 2009; 86:1485-92. [PMID: 20024545 DOI: 10.1007/s00253-009-2368-y] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2009] [Revised: 11/11/2009] [Accepted: 11/13/2009] [Indexed: 11/30/2022]
Abstract
Phosphomannomutase (ManB), whose main function is the conversion of mannose-6-phosphate to mannose-1-phosphate, is involved in biosynthesis of GDP-mannose for numerous processes such as synthesis of structural carbohydrates, production of alginates and ascorbic acid, and post-translational modification of proteins in prokaryotes and eukaryotes. ManB isolated from Streptomyces coelicolor was shown to have both phosphomannomutase and phosphoglucomutase activities. Deletion of manB in S. coelicolor caused a dramatic increase in actinorhodin (ACT) production in the low-glucose Difco nutrient (DN) medium, whereas the wild-type strain did not produce ACT on this medium. Experiments involving complementation of the manB deletion showed that increased ACT production in DN media was due to blockage of phosphomannomutase activity rather than phosphoglucomutase activity. This result therefore provides useful information for the design of strategies that enhance antibiotic production through the control of carbon flux.
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Affiliation(s)
- Yung-Hun Yang
- School of Chemical and Biological Engineering, Seoul National University, Seoul, Korea
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30
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Melino VJ, Soole KL, Ford CM. Ascorbate metabolism and the developmental demand for tartaric and oxalic acids in ripening grape berries. BMC PLANT BIOLOGY 2009; 9:145. [PMID: 19995454 PMCID: PMC2797797 DOI: 10.1186/1471-2229-9-145] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/07/2009] [Accepted: 12/09/2009] [Indexed: 05/18/2023]
Abstract
BACKGROUND Fresh fruits are well accepted as a good source of the dietary antioxidant ascorbic acid (Asc, Vitamin C). However, fruits such as grapes do not accumulate exceptionally high quantities of Asc. Grapes, unlike most other cultivated fruits do however use Asc as a precursor for the synthesis of both oxalic (OA) and tartaric acids (TA). TA is a commercially important product in the wine industry and due to its acidifying effect on crushed juice it can influence the organoleptic properties of the wine. Despite the interest in Asc accumulation in fruits, little is known about the mechanisms whereby Asc concentration is regulated. The purpose of this study was to gain insights into Asc metabolism in wine grapes (Vitis vinifera c.v. Shiraz.) and thus ascertain whether the developmental demand for TA and OA synthesis influences Asc accumulation in the berry. RESULTS We provide evidence for developmentally differentiated up-regulation of Asc biosynthetic pathways and subsequent fluctuations in Asc, TA and OA accumulation. Rapid accumulation of Asc and a low Asc to dehydroascorbate (DHA) ratio in young berries was co-ordinated with up-regulation of three of the primary Asc biosynthetic (Smirnoff-Wheeler) pathway genes. Immature berries synthesised Asc in-situ from the primary pathway precursors D-mannose and L-galactose. Immature berries also accumulated TA in early berry development in co-ordination with up-regulation of a TA biosynthetic gene. In contrast, ripe berries have up-regulated expression of the alternative Asc biosynthetic pathway gene D-galacturonic acid reductase with only residual expression of Smirnoff-Wheeler Asc biosynthetic pathway genes and of the TA biosynthetic gene. The ripening phase was further associated with up-regulation of Asc recycling genes, a secondary phase of increased accumulation of Asc and an increase in the Asc to DHA ratio. CONCLUSION We demonstrate strong developmental regulation of Asc biosynthetic, recycling and catabolic genes in grape berries. Integration of the transcript, radiotracer and metabolite data demonstrates that Asc and TA metabolism are developmentally regulated in grapevines; resulting in low accumulated levels of the biosynthetic intermediate Asc, and high accumulated levels of the metabolic end-product TA.
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Affiliation(s)
- Vanessa J Melino
- The University of Adelaide, School of Agriculture, Food and Wine, Private Mail Bag 1, Glen Osmond, SA, 5064, Australia
- Current address: Centre for Rhizobium Studies, Murdoch University, South Street, Murdoch, WA, 6150, Australia
| | - Kathleen L Soole
- Flinders University, School of Biological Sciences, PO Box 2100, Adelaide, SA, 5001, Australia
| | - Christopher M Ford
- The University of Adelaide, School of Agriculture, Food and Wine, Private Mail Bag 1, Glen Osmond, SA, 5064, Australia
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Badejo AA, Eltelib HA, Fukunaga K, Fujikawa Y, Esaka M. Increase in ascorbate content of transgenic tobacco plants overexpressing the acerola (Malpighia glabra) phosphomannomutase gene. PLANT & CELL PHYSIOLOGY 2009; 50:423-8. [PMID: 19122187 DOI: 10.1093/pcp/pcn206] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
Phosphomannomutase (PMM; EC 5.4.2.8) catalyzes the interconversion of mannose-6-phosphate to mannose-1-phosphate in the Smirnoff-Wheeler pathway for the biosynthesis of l-ascorbic acid (AsA). We have cloned the PMM cDNA from acerola (Malpighia glabra), a plant containing an enormous amount of AsA. The AsA contents correlate with the PMM gene expression of the ripening fruits and leaves. The PMM activities in the leaves of acerola, tomato and Arabidopsis correlate with their respective AsA contents. Transgenic tobacco plants overexpressing the acerola PMM gene showed about a 2-fold increase in AsA contents compared with the wild type, with a corresponding correlation with the PMM transcript levels and activities.
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32
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Hancock RD, Chudek JA, Walker PG, Pont SDA, Viola R. Ascorbic acid conjugates isolated from the phloem of Cucurbitaceae. PHYTOCHEMISTRY 2008; 69:1850-1858. [PMID: 18472116 DOI: 10.1016/j.phytochem.2008.03.022] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/02/2008] [Revised: 03/24/2008] [Accepted: 03/28/2008] [Indexed: 05/26/2023]
Abstract
Analysis of phloem exudates from the fruit of Cucurbitaceae revealed the presence of several compounds with UV-visible absorption spectra identical to that of l-ascorbic acid. In Cucurbita pepo L. (zucchini), the compounds could be isolated from phloem exudates collected from aerial parts of the plant but were not detected in whole tissue homogenates. The compounds isolated from the phloem exudates of C. pepo fruit were eluted from strong anion exchange resin in the same fraction as l-ascorbic acid and were oxidised by ascorbate oxidase (E.C. 1.10.3.3). The major compound purified from C. pepo fruit exudates demonstrated similar redox properties to l-ascorbic acid and synthetic 6-O-glucosyl-l-ascorbic acid (6-GlcAsA) but differed from those of 2-O-glucosyl-l-ascorbic acid (2-GlcAsA) isolated from the fruit of Lycium barbarum L. Parent and fragment ion masses of the compound were consistent with hexosyl-ascorbate in which the hexose moiety was attached to C5 or C6 of AsA. Acid hydrolysis of the major C. pepo compound resulted in the formation of l-ascorbic acid and glucose. The purified compound yielded a proton NMR spectrum that was almost identical to that of synthetic 6-GlcAsA. A series of l-ascorbic acid conjugates have, therefore, been identified in the phloem of Cucurbitaceae and the most abundant conjugate has been identified as 6-GlcAsA. The potential role of such conjugates in the long-distance transport of l-ascorbic acid is discussed.
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Affiliation(s)
- Robert D Hancock
- Scottish Crop Research Institute, Plant Products and Food Quality, Invergowrie, Dundee DD2 5DA, United Kingdom.
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33
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Facchini PJ, De Luca V. Opium poppy and Madagascar periwinkle: model non-model systems to investigate alkaloid biosynthesis in plants. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2008; 54:763-84. [PMID: 18476877 DOI: 10.1111/j.1365-313x.2008.03438.x] [Citation(s) in RCA: 135] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/20/2023]
Abstract
Alkaloids represent a large and diverse group of compounds that are related by the occurrence of a nitrogen atom within a heterocyclic backbone. Unlike other types of secondary metabolites, the various structural categories of alkaloids are unrelated in terms of biosynthesis and evolution. Although the biology of each group is unique, common patterns have become apparent. Opium poppy (Papaver somniferum), which produces several benzylisoquinoline alkaloids, and Madagascar periwinkle (Catharanthus roseus), which accumulates an array of monoterpenoid indole alkaloids, have emerged as the premier organisms used to study plant alkaloid metabolism. The status of these species as model systems results from decades of research on the chemistry, enzymology and molecular biology responsible for the biosynthesis of valuable pharmaceutical alkaloids. Opium poppy remains the only commercial source for morphine, codeine and semi-synthetic analgesics, such as oxycodone, derived from thebaine. Catharanthus roseus is the only source for the anti-cancer drugs vinblastine and vincristine. Impressive collections of cDNAs encoding biosynthetic enzymes and regulatory proteins involved in the formation of benzylisoquinoline and monoterpenoid indole alkaloids are now available, and the rate of gene discovery has accelerated with the application of genomics. Such tools have allowed the establishment of models that describe the complex cell biology of alkaloid metabolism in these important medicinal plants. A suite of biotechnological resources, including genetic transformation protocols, has allowed the application of metabolic engineering to modify the alkaloid content of these and related species. An overview of recent progress on benzylisoquinoline and monoterpenoid indole alkaloid biosynthesis in opium poppy and C. roseus is presented.
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Affiliation(s)
- Peter J Facchini
- Department of Biological Sciences, University of Calgary, Calgary, AB T2N 1N4, Canada.
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Abstract
Alkaloids represent a highly diverse group of compounds that are related only by the occurrence of a nitrogen atom in a heterocyclic ring. Plants are estimated to produce approximately 12,000 different alkaloids, which can be organized into groups according to their carbon skeletal structures. Alkaloid biosynthesis in plants involves many catalytic steps, catalyzed by enzymes that belong to a wide range of protein families. The characterization of novel alkaloid biosynthetic enzymes in terms of structural biochemistry, molecular and cell biology, and biotechnological applications has been the focus of research over the past several years. The application of genomics to the alkaloid field has accelerated the discovery of cDNAs encoding previously elusive biosynthetic enzymes. Other technologies, such as large-scale gene expression analyses and metabolic engineering approaches with transgenic plants, have provided new insights into the regulatory architecture of alkaloid metabolism.
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Affiliation(s)
- Jörg Ziegler
- Department of Biological Sciences, University of Calgary, Calgary, Alberta T2N 1N4, Canada.
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35
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Hancock RD, Walker PG, Pont SDA, Marquis N, Vivera S, Gordon SL, Brennan RM, Viola R. L-Ascorbic acid accumulation in fruit of Ribes nigrum occurs by in situ biosynthesis via the L-galactose pathway. FUNCTIONAL PLANT BIOLOGY : FPB 2008; 34:1080-1091. [PMID: 32689438 DOI: 10.1071/fp07221] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/12/2007] [Accepted: 10/22/2007] [Indexed: 06/11/2023]
Abstract
Blackcurrant (Ribes nigrum L.) is a widely grown commercial crop valued for its high vitamin C (l-ascorbic acid, AsA) content. In the present study, a systematic analysis of the mechanism of fruit AsA accumulation was undertaken. AsA accumulation occurred during fruit expansion and was associated with high in situ biosynthetic capacity via the l-galactose pathway and low rates of turnover. Cessation of AsA accumulation was associated with reduced biosynthesis and increased turnover. Translocation of AsA from photosynthetic or vegetative tissues contributed little to fruit AsA accumulation. Manipulation of substrate availability by defoliation had no effect on fruit AsA concentration but significantly reduced fruit yields. Supply of the AsA precursor l-galactono-1,4-lactone to intact, attached fruit transiently increased fruit AsA concentration which rapidly returned to control levels after removal of the compound. These data suggest strong developmental, metabolic and genetic control of AsA accumulation in blackcurrant fruit and indicate the potential for breeding high AsA cultivars.
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Affiliation(s)
- Robert D Hancock
- Scottish Crop Research Institute, Invergowrie, Dundee DD2 5DA, United Kingdom
| | - Paul G Walker
- Scottish Crop Research Institute, Invergowrie, Dundee DD2 5DA, United Kingdom
| | - Simon D A Pont
- Scottish Crop Research Institute, Invergowrie, Dundee DD2 5DA, United Kingdom
| | - Nicola Marquis
- Scottish Crop Research Institute, Invergowrie, Dundee DD2 5DA, United Kingdom
| | - Sebastian Vivera
- Scottish Crop Research Institute, Invergowrie, Dundee DD2 5DA, United Kingdom
| | - Sandra L Gordon
- Scottish Crop Research Institute, Invergowrie, Dundee DD2 5DA, United Kingdom
| | - Rex M Brennan
- Scottish Crop Research Institute, Invergowrie, Dundee DD2 5DA, United Kingdom
| | - Roberto Viola
- IASMA, Via E. Mach, S. Michele all'Adige, I-38010, Trento, Italy
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Hoeberichts FA, Vaeck E, Kiddle G, Coppens E, van de Cotte B, Adamantidis A, Ormenese S, Foyer CH, Zabeau M, Inzé D, Périlleux C, Van Breusegem F, Vuylsteke M. A Temperature-sensitive mutation in the Arabidopsis thaliana phosphomannomutase gene disrupts protein glycosylation and triggers cell death. J Biol Chem 2007; 283:5708-18. [PMID: 18086684 DOI: 10.1074/jbc.m704991200] [Citation(s) in RCA: 52] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Eukaryotic phosphomannomutases (PMMs) catalyze the interconversion of mannose 6-phosphate to mannose 1-phosphate and are essential to the biosynthesis of GDP-mannose. As such, plant PMMs are involved in ascorbic acid (AsA) biosynthesis and N-glycosylation. We report on the conditional phenotype of the temperature-sensitive Arabidopsis thaliana pmm-12 mutant. Mutant seedlings were phenotypically similar to wild type seedlings when grown at 16-18 degrees C but died within several days after transfer to 28 degrees C. This phenotype was observed throughout both vegetative and reproductive development. Protein extracts derived from pmm-12 plants had lower PMM protein and enzyme activity levels. In vitro biochemical analysis of recombinant proteins showed that the mutant PMM protein was compromised in its catalytic efficiency (K cat/K m). Despite significantly decreased AsA levels in pmm-12 plants, AsA deficiency could not account for the observed phenotype. Since, at restrictive temperature, total glycoprotein patterns were altered and glycosylation of protein-disulfide isomerase was perturbed, we propose that a deficiency in protein glycosylation is responsible for the observed cell death phenotype.
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Affiliation(s)
- Frank A Hoeberichts
- Department of Plant Systems Biology, Flanders Institute for Biotechnology (VIB), Ghent University, 9052 Gent, Belgium
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Khan JA, Wang Q, Sjölund RD, Schulz A, Thompson GA. An early nodulin-like protein accumulates in the sieve element plasma membrane of Arabidopsis. PLANT PHYSIOLOGY 2007; 143:1576-89. [PMID: 17293437 PMCID: PMC1851800 DOI: 10.1104/pp.106.092296] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/30/2006] [Accepted: 01/31/2007] [Indexed: 05/13/2023]
Abstract
Membrane proteins within the sieve element-companion cell complex have essential roles in the physiological functioning of the phloem. The monoclonal antibody line RS6, selected from hybridomas raised against sieve elements isolated from California shield leaf (Streptanthus tortuosus; Brassicaceae) tissue cultures, recognizes an antigen in the Arabidopsis (Arabidopsis thaliana) ecotype Columbia that is associated specifically with the plasma membrane of sieve elements, but not companion cells, and accumulates at the earliest stages of sieve element differentiation. The identity of the RS6 antigen was revealed by reverse transcription-PCR of Arabidopsis leaf RNA using degenerate primers to be an early nodulin (ENOD)-like protein that is encoded by the expressed gene At3g20570. Arabidopsis ENOD-like proteins are encoded by a multigene family composed of several types of structurally related phytocyanins that have a similar overall domain structure of an amino-terminal signal peptide, plastocyanin-like copper-binding domain, proline/serine-rich domain, and carboxy-terminal hydrophobic domain. The amino- and carboxy-terminal domains of the 21.5-kD sieve element-specific ENOD are posttranslationally cleaved from the precursor protein, resulting in a mature peptide of approximately 15 kD that is attached to the sieve element plasma membrane via a carboxy-terminal glycosylphosphatidylinositol membrane anchor. Many of the Arabidopsis ENOD-like proteins accumulate in gametophytic tissues, whereas in both floral and vegetative tissues, the sieve element-specific ENOD is expressed only within the phloem. Members of the ENOD subfamily of the cupredoxin superfamily do not appear to bind copper and have unknown functions. Phenotypic analysis of homozygous T-DNA insertion mutants for the gene At3g20570 shows minimal alteration in vegetative growth but a significant reduction in the overall reproductive potential.
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Affiliation(s)
- Junaid A Khan
- Department of Applied Science, University of Arkansas, Little Rock, Arkansas 72204-1099, USA
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Qian W, Yu C, Qin H, Liu X, Zhang A, Johansen IE, Wang D. Molecular and functional analysis of phosphomannomutase (PMM) from higher plants and genetic evidence for the involvement of PMM in ascorbic acid biosynthesis in Arabidopsis and Nicotiana benthamiana. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2007; 49:399-413. [PMID: 17217471 DOI: 10.1111/j.1365-313x.2006.02967.x] [Citation(s) in RCA: 69] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/13/2023]
Abstract
Phosphomannomutase (PMM) catalyzes the interconversion of mannose-6-phosphate and mannose-1-phosphate. However, systematic molecular and functional investigations on PMM from higher plants have hitherto not been reported. In this work, PMM cDNAs were isolated from Arabidopsis, Nicotiana benthamiana, soybean, tomato, rice and wheat. Amino acid sequence comparisons indicated that plant PMM proteins exhibited significant identity to their fungal and mammalian orthologs. In line with the similarity in primary structure, plant PMM complemented the sec53-6 temperature sensitive mutant of Saccharomyces cerevisiae. Histidine-tagged Arabidopsis PMM (AtPMM) purified from Escherichia coli converted mannose-1-phosphate into mannose-6-phosphate and glucose-1-phosphate into glucose-6-phosphate, with the former reaction being more efficient than the latter one. In Arabidopsis and N. benthamiana, PMM was constitutively expressed in both vegetative and reproductive organs. Reducing the PMM expression level through virus-induced gene silencing caused a substantial decrease in ascorbic acid (AsA) content in N. benthamiana leaves. Conversely, raising the PMM expression level in N. benthamiana using viral-vector-mediated ectopic expression led to a 20-50% increase in AsA content. Consistent with this finding, transgenic expression of an AtPMM-GFP fusion protein in Arabidopsis also increased AsA content by 25-33%. Collectively, this study improves our understanding on the molecular and functional properties of plant PMM and provides genetic evidence on the involvement of PMM in the biosynthesis of AsA in Arabidopsis and N. benthamiana plants.
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Affiliation(s)
- Weiqiang Qian
- The State Key Laboratory of Plant Cell and Chromosome Engineering, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing 100101, China
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Debolt S, Melino V, Ford CM. Ascorbate as a biosynthetic precursor in plants. ANNALS OF BOTANY 2007; 99:3-8. [PMID: 17098753 PMCID: PMC2802977 DOI: 10.1093/aob/mcl236] [Citation(s) in RCA: 72] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/25/2006] [Revised: 08/21/2006] [Accepted: 09/27/2006] [Indexed: 05/12/2023]
Abstract
BACKGROUND AND AIMS l-Ascorbate (vitamin C) has well-documented roles in many aspects of redox control and anti-oxidant activity in plant cells. This Botanical Briefing highlights recent developments in another aspect of l-ascorbate metabolism: its function as a precursor for specific processes in the biosynthesis of organic acids. SCOPE The Briefing provides a summary of recent advances in our understanding of l-ascorbate metabolism, covering biosynthesis, translocation and functional aspects. The role of l-ascorbate as a biosynthetic precursor in the formation of oxalic acid, l-threonic acid and l-tartaric acid is described, and progress in elaborating the mechanisms of the formation of these acids is reviewed. The potential conflict between the two roles of l-ascorbate in plant cells, functional and biosynthetic, is highlighted. CONCLUSIONS Recent advances in the understanding of l-ascorbate catabolism and the formation of oxalic and l-tartaric acids provide compelling evidence for a major role of l-ascorbate in plant metabolism. Combined experimental approaches, using classic biochemical and emerging 'omics' technologies, have provided recent insight to previously under-investigated areas.
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Affiliation(s)
| | | | - Christopher M. Ford
- School of Agriculture, Food and Wine, University of Adelaide, Waite Campus, PMB1, Glen Osmond, SA 5064, Australia
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Affiliation(s)
- Frank A Loewus
- Institute of Biological Chemistry, Washington State University, Pullman, WA 99164-6340, USA
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Samanani N, Alcantara J, Bourgault R, Zulak KG, Facchini PJ. The role of phloem sieve elements and laticifers in the biosynthesis and accumulation of alkaloids in opium poppy. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2006; 47:547-63. [PMID: 16813579 DOI: 10.1111/j.1365-313x.2006.02801.x] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/10/2023]
Abstract
The benzylisoquinoline alkaloids of opium poppy, including the narcotic analgesics morphine and codeine, accumulate in the multinucleate cytoplasm of specialized laticifers that accompany vascular tissues throughout the plant. In mature opium poppy plants, immunofluorescence labeling using specific antibodies showed that four alkaloid biosynthetic enzymes, (S)-norcoclaurine 6-O-methyltransferase (6OMT), (S)-coclaurine N-methyltransferase (CNMT), (S)-3'-hydroxy-N-methylcoclaurine-4'-O-methyltransferase (4'OMT) and salutaridinol-7-O-acetyltransferase (SAT) were restricted to sieve elements of the phloem adjacent or proximal to laticifers. The identity of sieve elements was confirmed by (i) the specific immunogold labeling of the characteristic cytoplasm of this cell type, (ii) the co-localization of a sieve element-specific H(+)-ATPase with all biosynthetic enzymes and (iii) the strict association of sieve plates with immunofluorescent cells. The localization of laticifers was demonstrated antibodies specific to major latex protein (MLP), which is characteristic of this cell type. In situ hybridization using antisense RNA probes for 6OMT, CNMT, 4'OMT and SAT showed that the corresponding gene transcripts were found in the companion cell paired with each sieve element. Seven benzylisoquinoline alkaloid biosynthetic enzymes, (S)-N-methylcoclaurine 3'-hydroxylase (CYP80B1), berberine bridge enzyme, codeinone reductase, 6OMT, CNMT, 4'OMT and SAT were localized by immunofluorescence labeling to the sieve elements in the root and hypocotyl of opium poppy seedlings. The abundance of these enzymes increased rapidly between 1 and 3 days after seed germination. The localization of seven biosynthetic enzymes to the sieve elements provides strong support for the unique, cell type-specific biosynthesis of benzylisoquinoline alkaloids in the opium poppy.
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Affiliation(s)
- Nailish Samanani
- Department of Biological Sciences, University of Calgary, Calgary, Alberta, T2N 1N4, Canada
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Major LL, Wolucka BA, Naismith JH. Structure and function of GDP-mannose-3',5'-epimerase: an enzyme which performs three chemical reactions at the same active site. J Am Chem Soc 2005; 127:18309-20. [PMID: 16366586 PMCID: PMC3315049 DOI: 10.1021/ja056490i] [Citation(s) in RCA: 67] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
GDP-mannose-3',5'-epimerase (GME) from Arabidopsis thaliana catalyzes the epimerization of both the 3' and 5' positions of GDP-alpha-D-mannose to yield GDP-beta-L-galactose. Production of the C5' epimer of GDP-alpha-D-mannose, GDP-beta-L-gulose, has also been reported. The reaction occurs as part of vitamin C biosynthesis in plants. We have determined structures of complexes of GME with GDP-alpha-D-mannose, GDP-beta-L-galactose, and a mixture of GDP-beta-L-gulose with GDP-beta-L-4-keto-gulose to resolutions varying from 2.0 to 1.4 A. The enzyme has the classical extended short-chain dehydratase/reductase (SDR) fold. We have confirmed that GME establishes an equilibrium between two products, GDP-beta-L-galactose and GDP-beta-L-gulose. The reaction proceeds by C4' oxidation of GDP-alpha-D-mannose followed by epimerization of the C5' position to give GDP-beta-L-4-keto-gulose. This intermediate is either reduced to give GDP-beta-L-gulose or the C3' position is epimerized to give GDP-beta-L-4-keto-galactose, then C4' is reduced to GDP-beta-L-galactose. The combination of oxidation, epimerization, and reduction in a single active site is unusual. Structural analysis coupled to site-directed mutagenesis suggests C145 and K217 as the acid/base pair responsible for both epimerizations. On the basis of the structure of the GDP-beta-L-gulose/GDP-beta-L-4-keto-gulose co-complex, we predict that a ring flip occurs during the first epimerization and that a boat intermediate is likely for the second epimerization. Comparison of GME with other SDR enzymes known to abstract a protein alpha to the keto function of a carbohydrate identifies key common features.
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Affiliation(s)
- Louise L Major
- Centre for Biomolecular Sciences, University of St. Andrews, North Haugh, St. Andrews, Fife, Scotland KY16 9ST, United Kingdom
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Facchini PJ, St-Pierre B. Synthesis and trafficking of alkaloid biosynthetic enzymes. CURRENT OPINION IN PLANT BIOLOGY 2005; 8:657-66. [PMID: 16182601 DOI: 10.1016/j.pbi.2005.09.008] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/09/2005] [Accepted: 09/13/2005] [Indexed: 05/04/2023]
Abstract
The biosynthesis of plant natural products involves a large number of enzymes that create and elaborate a bewildering array of chemical structures, which are generally involved in ecophysiological interactions. Alkaloids are one of the largest groups of natural products and are generally produced through an assortment of intricate pathways. The application of molecular biochemical approaches to investigate the cell biology of alkaloid pathways has revealed a paradigm for the complex, yet highly ordered, organization of biosynthetic enzymes at both the cellular and subcellular levels. Many different cell types have been implicated in alkaloid formation and storage, in one case suggesting the intercellular transport of enzymes. The localization of enzymes to numerous cellular compartments shows the importance of protein targeting in the assembly of alkaloid pathways. Recent studies have also pointed to the possible interaction of biosynthetic enzymes in multi-enzyme complexes. These processes must be considered to be integral components of the mechanisms that regulate alkaloid biosynthesis and perhaps other natural product pathways.
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Affiliation(s)
- Peter J Facchini
- Department of Biological Sciences, University of Calgary, Calgary, Alberta, T2N 1N4, Canada.
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Facchini PJ, Bird DA, Bourgault R, Hagel JM, Liscombe DK, MacLeod BP, Zulak KG. Opium poppy: a model system to investigate alkaloid biosynthesis in plants. ACTA ACUST UNITED AC 2005. [DOI: 10.1139/b05-094] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Remarkable progress on the biology of plant secondary metabolism has recently been realized. The application of advanced biochemistry, molecular, cellular, and genomic methodologies has revealed biological paradigms unique to the biosynthesis of secondary metabolites, including alkaloids, flavonoids, glucosinolates, phenylpropanoids, and terpenoids. The use of model plant systems has facilitated integrative research on the biosynthesis and regulation of each group of natural products. The model legume, Medicago truncatula Gaertn., plays a key role in studies on phenylpropanoid and flavonoid metabolism. Mint ( Mentha × piperita L.) and various conifers are the systems of choice to investigate terpenoid metabolism, whereas members of the mustard family (Brassica spp.) are central to work on glucosinolate pathways. Arabidopsis thaliana (L.) Heynh. is also used to study the biosynthesis of most secondary compounds, except alkaloids. Unlike other categories of secondary metabolites, the many structural types of alkaloids are biosynthetically unrelated. The biology of each group is unique, although common paradigms are also apparent. Opium poppy ( Papaver somniferum L.) produces a large number of benzylisoquinoline alkaloids and has begun to challenge Madigascar periwinkle ( Catharanthus roseus (L.) G. Don), which accumulates monoterpenoid indole alkaloids, as the most versatile model system to study alkaloid metabolism. An overview of recent progress on the biology of plant alkaloid biosynthesis, with a focus on benzylisoquinoline alkaloid pathways in opium poppy and related species, highlights the emergence of opium poppy as an important model system to investigate secondary metabolism.
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Affiliation(s)
- Peter J. Facchini
- Department of Biological Sciences, 2500 University Drive N.W., University of Calgary, Calgary, AB T2N 1N4, Canada
| | - David A. Bird
- Department of Biological Sciences, 2500 University Drive N.W., University of Calgary, Calgary, AB T2N 1N4, Canada
| | - Richard Bourgault
- Department of Biological Sciences, 2500 University Drive N.W., University of Calgary, Calgary, AB T2N 1N4, Canada
| | - Jillian M. Hagel
- Department of Biological Sciences, 2500 University Drive N.W., University of Calgary, Calgary, AB T2N 1N4, Canada
| | - David K. Liscombe
- Department of Biological Sciences, 2500 University Drive N.W., University of Calgary, Calgary, AB T2N 1N4, Canada
| | - Benjamin P. MacLeod
- Department of Biological Sciences, 2500 University Drive N.W., University of Calgary, Calgary, AB T2N 1N4, Canada
| | - Katherine G. Zulak
- Department of Biological Sciences, 2500 University Drive N.W., University of Calgary, Calgary, AB T2N 1N4, Canada
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45
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Hancock RD, Viola R. Improving the nutritional value of crops through enhancement of L-ascorbic acid (vitamin C) content: rationale and biotechnological opportunities. JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY 2005; 53:5248-57. [PMID: 15969504 DOI: 10.1021/jf0503863] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/03/2023]
Abstract
L-Ascorbic acid (AsA, vitamin C) is an essential human nutrient that must be obtained in the diet, with the vast majority being obtained from plant foods. A vitamin C-deficient diet results in the onset of scurvy, which can have lethal consequences. However, vitamin C has also been implicated in the prevention of chronic diseases such as heart disease, stroke, cancer, and several neurodegenerative diseases. Although the supporting evidence for these claims is disputed, the dietary allowances for vitamin C have been recently increased in several countries, including the United States. This scenario, together with the general perception by consumers of vitamin C as being of benefit in the prevention of several lifestyle diseases and associated with general "well-being", contributes to a market rationale for enhancing the vitamin C content of crops. In recent years, there has been substantial progress in the understanding of vitamin C biochemistry in plants with a number of structural genes cloned. Here these findings are reviewed, and a description of how such knowledge could be applied to the nutritional enhancement of crops is given.
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Affiliation(s)
- Robert D Hancock
- Quality, Health and Nutrition Programme, Scottish Crop Research Institute, Invergowrie, Dundee.
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46
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Laing WA, Bulley S, Wright M, Cooney J, Jensen D, Barraclough D, MacRae E. A highly specific L-galactose-1-phosphate phosphatase on the path to ascorbate biosynthesis. Proc Natl Acad Sci U S A 2004; 101:16976-81. [PMID: 15550539 PMCID: PMC534719 DOI: 10.1073/pnas.0407453101] [Citation(s) in RCA: 109] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2004] [Indexed: 11/18/2022] Open
Abstract
Ascorbate is a critical compound in plants and animals. Humans are unable to synthesize ascorbate, and their main source of this essential vitamin are plants. However, the pathway of synthesis in plants is yet to be established, and several unknown enzymes are only postulated to exist. We describe a specific L-galactose-1-phosphate (L-gal-1-P) phosphatase that we partially purified from young kiwifruit (Actinidia deliciosa) berries. The enzyme had a native molecular mass of approximately 65 kDa, was completely dependent on Mg2+ for activity and was very specific in its ability to hydrolyze L-gal-1-P. The activity had a pH optimum of 7.0, a K(-M(L-gal-1-P) of 20-40 microM and a Ka(Mg2+) of 0.2 mM. The activity was inhibited by Mg2+ at concentrations >2 mM. The enzyme from Arabidopsis thaliana shoots showed similar properties to the kiwifruit enzyme. The Arabidopsis thaliana enzyme preparation was digested with trypsin, and proteins present were identified by using liquid chromatography-MS. One of 24 proteins present in our preparation was an Arabidopsis thaliana protein, At3g02870, annotated myo-inositol-1-phosphate phosphatase in GenBank, that matched the characteristics of the purified l-gal-1-phosphate phosphatase. We then expressed a kiwifruit homologue of this gene in Escherichia coli and found that it showed 14-fold higher maximum velocity for l-gal-1-P than myo-inositol-1-P. The expressed enzyme showed very similar properties to the enzyme purified from kiwifruit and Arabidopsis, except that its KM(L-gal-1-P) and Ka(Mg2+) were higher in the expressed enzyme. The data are discussed in terms of the pathway to ascorbate biosynthesis in plants.
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Affiliation(s)
- William A Laing
- Gene Technologies Sector, Horticultural and Food Research Institute of New Zealand, Ltd., PB 92169, Auckland, New Zealand.
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Tedone L, Hancock RD, Alberino S, Haupt S, Viola R. Long-distance transport of L-ascorbic acid in potato. BMC PLANT BIOLOGY 2004; 4:16. [PMID: 15377389 PMCID: PMC521686 DOI: 10.1186/1471-2229-4-16] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/18/2004] [Accepted: 09/17/2004] [Indexed: 05/18/2023]
Abstract
BACKGROUND Following on from recent advances in plant AsA biosynthesis there is increasing interest in elucidating the factors contributing to the L-ascorbic acid (AsA) content of edible crops. One main objective is to establish whether in sink organs such as fruits and tubers, AsA is synthesised in situ from imported photoassimilates or synthesised in source tissues and translocated via the phloem. In the current work we test the hypothesis that long-distance transport is involved in AsA accumulation within the potato tuber, the most significant source of AsA in the European diet. RESULTS Using the EDTA exudation technique we confirm the presence of AsA in the phloem of potato plants and demonstrate a correlation between changes in the AsA content of source leaves and that of phloem exudates. Comparison of carboxyflourescein and AgNO3 staining is suggestive of symplastic unloading of AsA in developing tubers. This hypothesis was further supported by the changes in AsA distribution during tuber development which closely resembled those of imported photoassimilates. Manipulation of leaf AsA content by supply of precursors to source leaves resulted in increased AsA content of developing tubers. CONCLUSION Our data provide strong support to the hypothesis that long-distance transport of AsA occurs in potato. We also show that phloem AsA content and AsA accumulation in sink organs can be directly increased via manipulation of AsA content in the foliage. We are now attempting to establish the quantitative contribution of imported AsA to overall AsA accumulation in developing potato tubers via transgenic approaches.
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Affiliation(s)
- Luigi Tedone
- Unit of Plant Biochemistry, Scottish Crop Research Institute, Invergowrie, Dundee DD2 5DA, UK
- Dipartimento di Scienze delle Produzioni Vegetali, Universita degli Studi di Bari, Italy
| | - Robert D Hancock
- Unit of Plant Biochemistry, Scottish Crop Research Institute, Invergowrie, Dundee DD2 5DA, UK
| | - Salvatore Alberino
- Unit of Plant Biochemistry, Scottish Crop Research Institute, Invergowrie, Dundee DD2 5DA, UK
- University of Naples "Federico II", Department of Soil, Plant and Environmental Sciences, Via Universita' 100 – 80055 Portici, Italy
| | - Sophie Haupt
- Unit of Plant Biochemistry, Scottish Crop Research Institute, Invergowrie, Dundee DD2 5DA, UK
| | - Roberto Viola
- Unit of Plant Biochemistry, Scottish Crop Research Institute, Invergowrie, Dundee DD2 5DA, UK
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VAN Bel AJE, Gaupels F. Pathogen-induced resistance and alarm signals in the phloem. MOLECULAR PLANT PATHOLOGY 2004; 5:495-504. [PMID: 20565623 DOI: 10.1111/j.1364-3703.2004.00243.x] [Citation(s) in RCA: 50] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Abstract
SUMMARY Despite a long-standing notion of long-distance signals triggering systemic acquired resistance (SAR), the translocation pathway and the identity of the signals involved have not been determined with any degree of certainty. A critical assessment indicates that, in parallel to signalling via the phloem, alternative modes for SAR induction such as signalling via the xylem or air-borne signalling by volatile substances may occur. This review further evaluates several classes of compounds as being functional in systemic resistance signalling. Evidence in favour of SAR involvement of phloem-mobile substances such as salicylic acid, lipid-derived molecules, reactive oxygen species and components of the antioxidant machinery is contradictory, circumstantial or inconclusive, at best. Nitric oxide bound to proteins or thiols seems a good candidate for signalling, but has not been found in phloem sap thus far. No convincing support of the involvement in SAR of phloem-mobile substances such as calcium, oligosaccharides, peptides or RNA species, which function in other systemic signalling cascades, has yet been produced. Nevertheless, phloem-mobile macromolecules are considered as potential tools for SAR given their pivotal role in remote gene expression under stress conditions. In this framework, the existence of several cascades for signal generation along the phloem pathway is envisaged. Finally, recent methods for detection of molecular signals in phloem sap and their expression in companion cells are presented.
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Affiliation(s)
- Aart J E VAN Bel
- Plant Cell Biology Research Group, Institute of General Botany, Senckenbergstrasse 17, 35390 Giessen, and Institute of Phytopathology, IFZ, Heinrich-Buff-Ring 26-32, 35392 Giessen, Justus Liebig University, Giessen, Germany
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Walz C, Giavalisco P, Schad M, Juenger M, Klose J, Kehr J. Proteomics of curcurbit phloem exudate reveals a network of defence proteins. PHYTOCHEMISTRY 2004; 65:1795-804. [PMID: 15276438 DOI: 10.1016/j.phytochem.2004.04.006] [Citation(s) in RCA: 117] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/12/2004] [Revised: 03/31/2004] [Indexed: 05/20/2023]
Abstract
Many different proteins can be separated from the sap of mature sieve tubes of different plant species. To date, only a limited number of those have been identified and functionally characterised. Due to sieve tubes inability of transcription and translation, the proteins are most probably synthesised in the intimately connected companion cells and transported into the sieve elements through plasmodesmata. The specific protein composition of phloem sap suggests an important role of these proteins not only for sieve tube maintenance, but also for whole plant physiology and development. Here we describe a comprehensive analysis of the phloem protein composition employing one- and high-resolution two-dimensional gel electrophoresis and partial sequencing by mass spectrometry. In this study more than 300 partial sequences generated by hybrid mass spectrometry were used to identify a total of 45 different proteins from the phloem exudates of cucumber (Cucumis sativus L. cv. Hoffmanns Giganta) and pumpkin (Cucurbita maxima Duch. cv. Gelber Zentner) plants. In addition to previously described phloem proteins, it was possible to localise proteins with high similarity to an acyl-CoA binding protein, a glyoxalase, a malate dehydrogenase, a rhodanese-like protein, a drought-induced protein, and a beta-glucosidase. The results indicate that the majority of the so far identified proteins are involved in stress and defence reactions.
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Affiliation(s)
- Christina Walz
- Department L. Willmitzer, Max-Planck-Institute of Molecular Plant Physiology, Am Muehlenberg 1, 14424 Potsdam, Germany
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