Polyamines Confer Salt Tolerance in Mung Bean (Vigna radiata L.) by Reducing Sodium Uptake, Improving Nutrient Homeostasis, Antioxidant Defense, and Methylglyoxal Detoxification Systems.

Kamrun Nahar,Mirza Hasanuzzaman,Masayuki Fujita,Anisur Rahman,Toshisada Suzuki,Jubayer-Al Mahmud,Md Mahabub Alam

doi:10.3389/fpls.2016.01104

Kamrun Nahar, Mirza Hasanuzzaman + Show 5 more

Open Access

https://doi.org/10.3389/fpls.2016.01104

Copy DOI

Abstract

The physiological roles of PAs (putrescine, spermidine, and spermine) were investigated for their ability to confer salt tolerance (200 mM NaCl, 48 h) in mung bean seedlings (Vigna radiata L. cv. BARI Mung-2). Salt stress resulted in Na toxicity, decreased K, Ca, Mg, and Zn contents in roots and shoots, and disrupted antioxidant defense system which caused oxidative damage as indicated by increased lipid peroxidation, H2O2 content, generation rate, and lipoxygenase activity. Salinity-induced methylglyoxal (MG) toxicity was also clearly evident. Salinity decreased leaf chlorophyll (chl) and relative water content (RWC). Supplementation of salt affected seedlings with exogenous PAs enhanced the contents of glutathione and ascorbate, increased activities of antioxidant enzymes (dehydroascorbate reductase, glutathione reductase, catalase, and glutathione peroxidase) and glyoxalase enzyme (glyoxalase II), which reduced salt-induced oxidative stress and MG toxicity, respectively. Exogenous PAs reduced cellular Na content and maintained nutrient homeostasis and modulated endogenous PAs levels in salt affected mung bean seedlings. The overall salt tolerance was reflected through improved tissue water and chl content, and better seedling growth.

Highlights

Plants show susceptibility to various stresses under both wild and cultivated conditions
Plants can scavenge a certain amount of reactive oxygen species (ROS) generated as by-products of aerobic metabolism, but under stress conditions, including salt stress, the resulting photoinhibition often creates an imbalance between ROS generation and scavenging due to generation of excessive amount of ROS, thereby resulting in oxidative stress, causing peroxidation of lipids, oxidation of proteins, inhibition of enzyme activity, injury to nucleic acids, activation of programmed cell death (PCD) pathways, and eventually leading to death of the cells (Gill and Tuteja, 2010; Hasanuzzaman et al, 2013)
High cellular Na content, imbalances in the mineral nutrients, oxidative damage, MG toxicity, and growth inhibition were the characteristic symptoms of salt stress affected mung bean seedlings

Summary

Introduction

Plants show susceptibility to various stresses under both wild and cultivated conditions. Plants can scavenge a certain amount of ROS generated as by-products of aerobic metabolism, but under stress conditions, including salt stress, the resulting photoinhibition often creates an imbalance between ROS generation and scavenging due to generation of excessive amount of ROS, thereby resulting in oxidative stress, causing peroxidation of lipids, oxidation of proteins, inhibition of enzyme activity, injury to nucleic acids, activation of programmed cell death (PCD) pathways, and eventually leading to death of the cells (Gill and Tuteja, 2010; Hasanuzzaman et al, 2013). Efficient enzymatic (superoxide dismutase, SOD; catalase, CAT; ascorbate peroxidase, APX; glutathione reductase, GR; monodehydroascorbate reductase, MDHAR; dehydroascorbate reductase, DHAR; glutathione peroxidase, GPX; guaicol peroxidase, GOPX; and glutathione S-transferase, GST) and non-enzymatic (ascorbate, AsA; glutathione, GSH; phenolic compounds, alkaloids, non-protein amino acids, and α-tocopherols) components form an antioxidant defense system to protect overproduction of ROS and to prevent plant cells from experiencing oxidative damage (Gill and Tuteja, 2010)

Methods

Results

Discussion

Conclusion