A novel aldo-keto reductase gene, IbAKR, from sweet potato confers higher tolerance to cadmium stress in tobacco

Abstract

High concentrations of Cd can inhibit growth and reduce the activity of the photosynthetic apparatus in plants. In several plant species, aldo-keto reductases (AKRs) have been shown to enhance tolerance to various abiotic stresses by scavenging cytotoxic aldehydes; however, few AKRs have been reported to enhance Cd stress tolerance. In this study, the gene IbAKR was isolated from sweet potato. The relative expression levels of IbAKR increased significantly (approximately 3-fold) after exposure to 200 mmol·L⁻¹ CdCl₂ or 10 mmol·L⁻¹ H₂O₂. A subcellular localization assay showed that IbAKR is predominantly located in the nucleus and cytoplasm. IbAKR-overexpressing tobacco plants showed higher tolerance to Cd stress than wild-type (WT). Transgenic lines showed a significant ability to scavenge malondialdehyde (MDA) and methylglyoxal (MG). In addition, proline content and superoxide dismutase activity were significantly higher and H₂O₂ levels were significantly lower in the transgenic plants than in the WT. Quantitative real-time PCR analysis showed that the reactive oxygen species (ROS) scavenging genes encoding guaiacol peroxidase (GPX), ascorbate peroxidase (APX), monodehydroascorbate reductase (MDHAR) and peroxidase (POD) were significantly upregulated in transgenic plants compared to WT under Cd stress. These findings suggest that overexpressing IbAKR enhances tolerance to Cd stress via the scavenging of cytotoxic aldehydes and the activation of the ROS scavenging system.

Keywords

cadmium stress / IbAKR / Ipomoea batatas / sweet potato

References

[1] Zhang X, Zhong T, Liu L, Ouyang X. Impact of soil heavy metal pollution on food safety in China. PLoS One, 2015, 10(8): e0135182

[2] Gallego S M, Pena L B, Barcia R A, Azpilicueta C E, Iannone M F, Rosales E P, Zawoznik M S, Groppa M D, Benavides M P. Unravelling cadmium toxicity and tolerance in plants: insight into regulatory mechanisms. Environmental and Experimental Botany, 2012, 83(5): 33–46

[3] Singh S, Parihar P, Singh R, Singh V P, Prasad S M. Heavy metal tolerance in plants: role of transcriptomics, proteomics, metabolomics, and ionomics. Frontiers in Plant Science, 2016, 6: 1143

[4] Penning T M. The aldo-keto reductases (AKRs): overview. Chemico-Biological Interactions, 2015, 234: 236–246

[5] Oberschall A, Deák M, Török K, Sass L, Vass I, Kovács I, Fehér A, Dudits D, Horváth G V. A novel aldose/aldehyde reductase protects transgenic plants against lipid peroxidation under chemical and drought stresses. Plant Journal, 2000, 24(4): 437–446

[6] Hideg É, Nagy T, Oberschall A, Dudits D, Vass I. Detoxification function of aldose/aldehyde reductase during drought and ultraviolet-B (280–320 nm) stresses. Plant, Cell & Environment, 2003, 26(4): 513–522

[7] Hegedüs A, Erdei S, Janda T, Tóth E, Horváth G, Dudits D. Transgenic tobacco plants overproducing alfalfa aldose/aldehyde reductase show higher tolerance to low temperature and cadmium stress. Plant Science, 2004, 166(5): 1329–1333

[8] Turóczy Z, Kis P, Török K, Cserháti M, Lendvai A, Dudits D, Horváth G V. Overproduction of a rice aldo-keto reductase increases oxidative and heat stress tolerance by malondialdehyde and methylglyoxal detoxification. Plant Molecular Biology, 2011, 75(4-5): 399–412

[9] Vemanna R S, Vennapusa A R, Easwaran M, Chandrashekar B K, Rao H, Ghanti K, Sudhakar C, Mysore K S, Makarla U. Aldo-keto reductase enzymes detoxify glyphosate and improve herbicide resistance in plants. Plant Biotechnology Journal, 2017, 15(7): 794–804

[10] Kumar D, Singh P, Yusuf M A, Upadhyaya C P, Roy S D, Hohn T, Sarin N B. The Xerophyta viscosa aldose reductase (ALDRXV4) confers enhanced drought and salinity tolerance to transgenic tobacco plants by scavenging methylglyoxal and reducing the membrane damage. Molecular Biotechnology, 2013, 54(2): 292–303

[11] Éva C, Zelenyánszki H, Tömösközi-Farkas R, Tamás L. Overproduction of an Arabidopsis aldo-keto reductase increases barley tolerance to oxidative and cadmium stress by an in vivo reactive aldehyde detoxification. Plant Growth Regulation, 2014, 74(1): 55–63

[12] Éva C, Zelenyánszk H, Tömösközi-Farkas R, Tamás L. Transgenic barley expressing the Arabidopsis AKR4C9 aldo-keto reductase enzyme exhibits enhanced freezing tolerance and regenerative capacity. South African Journal of Botany, 2014, 93(93): 179–184

[13] Kanayama Y, Mizutani R, Yaguchi S, Hojo A, Ikeda H, Nishiyama M, Kanahama K. Characterization of an uncharacterized aldo-keto reductase gene from peach and its role in abiotic stress tolerance. Phytochemistry, 2014, 104(3): 30–36

[14] He W, Zhang L, Yi S, Tang X, Yuan Q, Guo M, Wu A, Qu B, Li H, Liao Y. An aldo-keto reductase is responsible for Fusarium toxindegrading activity in a soil Sphingomonas strain. Scientific Reports, 2017, 7(1): 1–13

[15] Nisarga K N, Vemanna R S, Chandrashekar B K, Rao H, Vennapusa A R, Narasimaha A, Makarla U, Basavaiah M R. Aldo-ketoreductase 1 (AKR1) improves seed longevity in tobacco and rice by detoxifying reactive cytotoxic compounds generated during ageing. Rice, 2017, 10(1): 1–12

[16] Wang Y, Li Y, Zhang H, Zhai H, Liu Q, He S. A soluble starch synthase I gene, IbSSI, alters the content, composition, granule size and structure of starch in transgenic sweet potato. Scientific Reports, 2017, 7(1): 2315

[17] Cheng S, Huang C. Accumulation of cadmium uptake from soil in the edible root of root vegetables. Journal of Environmental Sciences, 2007, 17(2): 137–142

[18] Schmittgen T D, Livak K J. Analyzing real-time PCR data by the comparative C_T method. Nature Protocols, 2008, 3(6): 1101–1108

[19] Horsch R B, Fry J E, Hoffmann N L, Eichholtz D, Rogers S G, Fraley R T. A simple and general method for transferring genes into plants. Science, 1985, 227(4691): 1229–1231

[20] Gao S, Yuan L, Zhai H, Liu C, He S, Liu Q. Transgenic sweet potato plants expressing an LOS5 gene are tolerant to salt stress. Plant Cell, Tissue and Organ Culture, 2011, 107(2): 205–213

[21] He S, Han Y, Wang Y, Zhai H, Liu Q. In vitro selection and identification of sweet potato (Ipomoea batatas (L.) Lam.) plants tolerant to NaCl. Plant Cell, Tissue and Organ Culture, 2009, 96(1): 69–74

[22] Alexieva V, Sergiev I, Mapelli S, Karanov E. The effect of drought and ultraviolet radiation on growth and stress markers in pea and wheat. Plant, Cell & Environment, 2001, 24(12): 1337–1344

[23] Porra R J, Thompson W A, Kriedemann P E. Determination of accurate extinction coefficients and simultaneous equations for assaying chlorophylls a and b extracted with four different solvents: verification of the concentration of chlorophyll standards by atomic absorption spectroscopy. BBA–Bioenergetics, 1989, 975(3): 384–394

[24] Agrawal C, Sen S, Yadav S, Rai S, Rai L C. A novel aldo-keto reductase (AKR17A1) of Anabaena sp. PCC 7120 degrades the rice field herbicide butachlor and confers tolerance to abiotic stresses in E. coli. PLoS One, 2015, 10(9): e0137744

[25] Jez J M, Bennett M J, Schlegel B P, Lewis M, Penning T M. Comparative anatomy of the aldo-keto reductase superfamily. Biochemical Journal, 1997, 326(3): 625–636

[26] Hyndman D, Bauman D R, Heredia V V, Penning T M. The aldo-keto reductase superfamily homepage. Chemico-Biological Interactions, 2003, 143– 144(2): 621–631

[27] Ayala A, Muñoz M F, Argüelles S. Lipid peroxidation: production, metabolism, and signaling mechanisms of malondialdehyde and 4-hydroxy-2-nonenal. Oxidative Medicine and Cellular Longevity, 2014, 2014(6): 360438

[28] Ray S, Dutta S, Halder J, Ray M. Inhibition of electron flow through complex I of the mitochondrial respiratory chain of Ehrlich ascites carcinoma cells by methylglyoxal. Biochemical Journal, 1994, 303(1): 69–72

[29] Gill S S, Tuteja N. Reactive oxygen species and antioxidant machinery in abiotic stress tolerance in crop plants. Plant Physiology and Biochemistry, 2010, 48(12): 909–930

[30] You J, Chan Z. ROS regulation during abiotic stress responses in crop plants. Frontiers in Plant Science, 2015, 6(12): 1092

[31] Karuppanapandian T, Moon J C, Kim C, Manoharan K, Kim W. Reactive oxygen species in plants: their generation, signal transduction, and scavenging mechanisms. Australian Journal of Crop Science, 2011, 5(6): 709–725

[32] Alia M P, Mohanty P, Matysik J. Effect of proline on the production of singlet oxygen. Amino Acids, 2001, 21(2): 195–200

Supplementary materials

The online version of this article at https://doi.org/10.15302/J-FASE-2018225 contains supplementary materials (Table S1; Fig. S1).

Acknowledgements

ƒWe thank Dr. Daniel Q. Tong, University of Maryland, USA, for English improvement. This work was supported by the National Natural Science Foundation of China (31271777) and the China Agriculture Research System (CARS-10, Sweet potato).

Compliance with ethics guidelines

ƒJinxi Huo, Bing Du, Sifan Sun, Shaozhen He, Ning Zhao, Qingchang Liu, and Hong Zhai declare that they have no conflicts of interest or financial conflicts to disclose.ƒ

This article does not contain any studies with human or animal subjects performed by any of the authors.

RIGHTS & PERMISSIONS

The Author(s) 2018. Published by Higher Education Press. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0)