TGase regulates salt stress tolerance through enhancing bound polyamines-mediated antioxidant enzymes activity in tomato
Introduction
Salinity stress is one of the most important environmental stresses adversely affects worldwide agricultural productivity (Munns and Tester, 2008; Shabala, 2013). It subsequently causes ionic, osmotic, and oxidative stress to plant. Excess levels of Na+ was absorbed in the cytosol hinders water uptake and leads to adverse physiological response, including disorders of ion homeostasis, stomatal closure, photosynthesis inhibition and biomass loss, thereby resulting in ion toxicity and osmotic damage (Zhu, 2002). Additionally, salinity stress leads to oxidative stress through an over-accumulation of reactive oxygen species (ROS) (Zhang et al., 2011). High levels of ROS that cause a loss of crop productivity and negatively affect cellular functions and damage to DNA, protein or lipids (Schieber and Chandel, 2014). Fortunately, plant have evolved a fine and complex enzymatic antioxidant system to repair damage initiated by ROS, such as superoxide dismutase (SOD), ascorbate catalase (CAT), peroxidase (APX) and monodehydroascorbate reductase (MDAR) (Mittler et al., 2004; Nahar et al., 2016). For instance, application of exogenous phytohormones and phytoprotectants induced the gene expression of antioxidant enzyme and increased their activities, which mitigated the detrimental effects of salt stress (Qiu et al., 2014; Rizwan et al., 2015; Wang et al., 2015). In other cases, manipulation of SOD, CAT and APX biosynthesis have all been demonstrated to enhance salt tolerance and neutralize salt-induced oxidative damage (Badawi et al., 2004; Luo et al., 2013). However, the regulatory mechanisms involved in these antioxidant enzymes are still not fully understood.
Polyamines (PAs) are present in free forms, or are often conjugated forms and interact with several important macromolecules (bound forms) (Groppa and Benavides, 2008; Michael, 2016). Free PAs, one of the original and important PA species, are widely distributed and response to various abiotic stress through increasing antioxidant enzyme activity (Alcázar et al., 2010; Gupta et al., 2013). Additionally, it has been demonstrated that conjugated or bound PAs exhibit higher ability to stability or activate antioxidant enzyme activity than free PAs through their cross-linked with antioxidant enzyme (Shevyakova et al., 2006; Saha et al., 2015). Although the crucial roles of conjugated and bound PAs have been demonstrated in a series of different biological processes, including salt stress response, our understanding about the regulatory mechanism of conjugated and bound PAs is extremely limited. Most studies on the regulation mechanism of conjugated and bound PAs has focused on the transglutaminase (TGase) (mediator of PA) (Del Duca et al., 1997, 2000). TGases catalyze the protein-bound glutamine residues incorporated into the primary amino groups of PAs, resulting in covalent posttranslational modification of proteins (Lilley et al., 1998). Endogenous bound Put increment is accompanied by an increase TGase activity was observed in plants under natural conditions, indicating that TGase is a positive mediator of bound PAs in plants (Pintó-Marijuan et al., 2007). Additionally, PAs were conjugated to light-harvesting complex of photosystem II (LHCII) to protect the structural stability by TGase (Della Mea et al., 2004). Thus, TGase may mediate the levels of conjugated and bound PAs in plants. Recently, we found that overexpression of TGase enhance salt tolerance and induced the accumulation of PAs in chloroplast, suggesting the possible involvement of TGase in bound PAs accumulation (Zhong et al., 2019b). However, little information is available concerning the functions and regulation of mechanisms between TGase and bound PAs under salt stress conditions.
To examine the potential function of TGase by genetic manipulation, we generated TGase-overexpressing tomato plant and compared their salt tolerance, endogenous conjugated and bound PAs content, Na+/K+ homeostasis, antioxidant enzyme activity with wild type (WT) plants. To our knowledge, this is the first study by genetic manipulation to demonstrate that the PA mediator TGase through maintaining bound PAs-mediated activity of antioxidant enzyme, and decreasing ROS over-production, thereby alleviating oxidative damage, which play a critical role in increasing plant tolerance to salt stress. Additionally, our results indicate that the regulation of free PAs to bound PAs by TGase might be a valid strategy for the improvement of plant’ abiotic stress tolerance.
Section snippets
Plant materials and treatments
Seeds of Solanum lycopersicum cv. ‘Ailsa Craig’ from WT and transgenic plants were germinated in quartz sand and cultured in a greenhouse at 28 ± 2℃/20 ± 2℃ (day/night) under a maximum photosynthetic photon flux density (PPFD) of approximately 1200 μmol m−2 s−1 with a relative humidity of 70–80 %. In Experiment I, abiotic stresses were induced in WT seedling at the 30-day-old, RNA samples were collected from leaves under the control condition and under different stress conditions over 6 h.
TGase expression was induced by abiotic stresses
Given that gene transcription levels under abiotic stresses may be related to gene functions, the TGase responded to a wide range of abiotic stresses was associated using WT seedling at 30-day. Samples were collected under the control and stress conditions for 6 h; stress consisted of NaCl, drought, heat and cold. Significantly increased TGase expression was observed under abiotic treatments compared with the expression in plants under normal conditions, with the exception of cold treatment. As
Discussion
Results reported here indicate that TGase was induced by abiotic stresses, and expression analysis shown that TGase was induced in WT plants under salt stress, the highest expression level being examined in upper adult leaves. These results indicate that TGase involved in adaptive response to salinity through protecting tissue from physiological caused by salt stress (Fig. 1, Fig. 2B). Comparable results were reported for TGase activity strongly increased to protect the tissue and
Author statement
Neither the entire paper nor any part of its content has been published or accepted elsewhere. It is not being submitted to any other journal. All of the authors have read and approved the final version of the manuscript and approved its submission to Environmental and Experimental Botany. The authors further declare no competing interests.
Author contributions
SG designed the research and supervised this study. MZ performed the experiments and wrote the original draft. YW revised the manuscript. SS and JS improved the manuscript. All authors reviewed and approved the manuscript.
Declaration of Competing Interest
The authors declare that they have no conflict of interest.
Acknowledgements
This work was supported by the National Natural Science Foundation of China (31672199 and 31801902), the China Earmarked Fund for Modern Agro-industry Technology Research System (CARS-23-B12) and the Fundamental Research Funds for the Central Universities (KJQN201928). ZM thanks the inimitable care and support of SR over the years. I love you forever and spend the rest of my life with you.
References (61)
- et al.
The ins and outs of intracellular ion homeostasis: NHX-type cation/H+ transporters
Curr. Opin. Plant Biol.
(2014) Factors affecting transglutaminase activity catalysing polyamine conjugation to endogenous substrates in the entire chloroplast
Plant Physiol. Biochem.
(2000)Inhibition of nitrite formation from hydroxylammoniumch-loride: a simple assay for superoxide dismutase
Anal. Biochem.
(1976)Nitric oxide enhances salt tolerance in cucumber seedlings by regulating free polyamine content
Environ. Exp. Bot.
(2013)Relationship between osmotic stress and the levels of free, conjugated and bound polyamines in leaves of wheat seedlings
Plant Sci.
(2004)Effect of osmotic stress on the activity of H+-ATPase and the levels of covalently and noncovalently conjugated polyamines in plasma membrane preparation from wheat seedling roots
Plant Sci.
(2005)- et al.
Analysis of relative gene expression data using real-time quantitative PCR and the 2−ΔΔCT method
Methods
(2001) Synergistic effects of GhSOD1 and GhCAT1 overexpression in cotton chloroplasts on enhancing tolerance to methyl viologen and salt stresses
PLoS One
(2013)Oxidative stress, antioxidants and stress tolerance
Trends Plant Sci.
(2002)Reactive oxygen gene network of plants
Trends Plant Sci.
(2004)
Exogenous jasmonic acid can enhance tolerance of wheat seedlings to salt stress
Ecotoxicol. Environ. Saf.
ROS function in redox signaling and oxidative stress
Curr. Biol.
The positive regulation of putrescine on light-harvesting complex II and excitation energy dissipation in salt-stressed cucumber seedlings
Environ. Exp. Bot.
Putrescine enhances salt tolerance of cucumber seedlings by regulating ion homeostasis
Environ. Exp. Bot.
Polyamines: molecules with regulatory functions in plant abiotic stress tolerance
Planta
Transglutaminase as polyamine mediator in plant growth and differentiation
Amino Acids
Lipids and proteins-major targets of oxidative modifications in abiotic stressed plants
Environ. Sci. Pollut. Res.
Production and scavenging of reactive oxygen species in chloroplasts and their functions
Plant Physiol.
Two closely linked tomato HKT coding genes are positional candidates for the major tomato QTL involved in Na+/K+ homeostasis
Plant Cell Environ.
Enhanced tolerance to salt stress and water deficit by overexpressing superoxide dismutase in tobacco (Nicotiana tabacum) chloroplasts
Plant Sci.
Single-cell measurements of the contributions of cytosolic Na+ and K+ to salt tolerance
Plant Physiol.
Transglutaminase-catalyzed modification of cytoskeletal proteins by polyamines during the germination of Malus domestica pollen
Sex. Plant Reprod.
A Zea mays 39-kDa thylakoid transglutaminase catalyses the modification by polyamines of light-harvesting complex II in a light-dependent way
Planta
Differential localization of antioxidants in maize leaves
Plant Physiol.
Polyamines and abiotic stress tolerance in plants
Plant Signal. Behav.
Polyamines and abiotic stress: recent advances
Amino Acids
Plant polyamines in abiotic stress responses
Acta Physiol. Plant.
Hydrogen peroxide and polyamines act as double edged swords in plant abiotic stress responses
Front. Plant Sci.
Increased tolerance to salt stress in OPDA-deficient rice ALLENE OXIDE CYCLASE mutants is linked to an increased ROS-scavenging activity
J. Exp. Bot.
Improving the thiobarbituric acid-reactive-substances assay for estimating lipid peroxidation in plant tissues containing anthocyanin and other interfering compounds
Planta
Cited by (30)
Calcium combined with vacuum treatment improves postharvest storage quality of Agaricus bisporus by regulating polyamine metabolism
2024, Postharvest Biology and TechnologyOptimization of stress tolerance index for screening of multiple abiotic stress tolerant genotype and determination of reliable trait in Cicer arieitnum L.
2023, Total Environment Research ThemesTGase-induced Cd tolerance by boosting polyamine, nitric oxide, cell wall composition and phytochelatin synthesis in tomato
2023, Ecotoxicology and Environmental SafetyPutrescine transformation to other forms of polyamines in filling grain embryos functioned in enhancing the resistance of maize plants to drought stress
2023, Plant Physiology and BiochemistryConjugated polyamines are involved in conformation stability of plasma membrane from maturing maize grain embryos under drought stress
2022, Environmental and Experimental BotanyCitation Excerpt :Plant growth and crop yield are greatly affected by high temperature (Goyal et al., 2010), salt (Zheng et al., 2016; Zhong et al., 2020), heavy metal (Rakić et al., 2021) and water stress (Maheswari et al., 2016; Ouyang et al., 2020; Ebmeyer et al., 2021).
- 1
These authors contributed equally: Min Zhong, Ran Song.