Overexpression of an alfalfa glutathione S-transferase gene improved the saline-alkali tolerance of transgenic tobacco.

Binghao Du,Xue Zhang,Yimin An,Yakun Li,Lili Song,Changhong Guo

doi:10.1242/bio.043505

Abstract

ABSTRACTAbiotic stresses restrict the productivity and quality of agricultural crops. Glutathione S-transferase (GST) utilizes glutathione to scavenge reactive oxygen species (ROS) that result from abiotic stresses. This study aimed to determine the expression pattern of the MsGSTU8 gene and its effects on saline-alkali tolerance. MsGSTU8, from alfalfa (Medicago sativa ‘Zhaodong’), was transformed into transgenic tobacco (Nicotiana tabacum) and overexpressed to determine its effects on saline-alkali tolerance. The gene products in alfalfa localized to the cytoplasm and the transcript levels were higher in the leaves than the roots and stems. Expression was strongly induced by cold, drought, salt and saline-alkali stresses as well as abscisic acid (ABA) treatments. The transgenic tobacco lines had significantly higher transcription levels of the abiotic stress-related genes and higher GST activity than the wild types. Transgenic tobacco lines with saline-alkali treatments maintained their chlorophyll content, showed improved antioxidant enzyme activity and soluble sugar levels, reduced ion leakage, O2.−, H2O2 accumulation and malondialdehyde content. Our results indicate that overexpression of MsGSTU8 could improve resistance to saline-alkali stresses by decreasing the accumulation of ROS and increasing the levels of antioxidant enzymes. Furthermore, they suggest that MsGSTU8 could be utilized for transgenic crop plant breeding.

Highlights

Plants regularly have to cope with abiotic stresses such as cold, heat, drought, salt and saline-alkali environments during their growth and development (Yu et al, 2018), which can seriously affect their yield and quality (Bechtold and Field, 2018; Shameer and Prasad, 2018)
The MsGSTU8 protein is localized in the cytoplasm The subcellular localization of MsGSTU8 was investigated using the MsGSTU8 and green fluorescence protein (GFP) fusion proteins that were overexpressed in Arabidopsis protoplast
This shows that the MsGSTU8 gene was induced by the stress treatments, and that the MsGSTU8 gene might be located at the crossing point of multiple abiotic stress response pathways

Summary

Introduction

Plants regularly have to cope with abiotic stresses such as cold, heat, drought, salt and saline-alkali environments during their growth and development (Yu et al, 2018), which can seriously affect their yield and quality (Bechtold and Field, 2018; Shameer and Prasad, 2018). In the process of plant evolution, plants have developed various response mechanisms, especially molecular reaction pathways and regulatory networks, in order to adapt to abiotic stresses (Qu et al, 2013). Glutathione S-transferases (GSTs; EC 2.5.1.18) are a group of multifunctional protective cellular enzymes found in all cellular organisms and are encoded by a large complex superfamily in plants (Abdul et al, 2018; Liu et al, 2017). Immunological reactivity, kinetic properties and structural conformation, GSTs have been found to be widespread among plants

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