Characterization of GABA-Transaminase Gene from Mulberry (Morus multicaulis) and Its Role in Salt Stress Tolerance.

Mengru Zhang,Yingping Gai,Chaorui Liu,Yiting Fan,Hairui Wang,Xianling Ji,Zhaoyang Liu,Yan Li,Youchao Xin

doi:10.3390/genes13030501

Mengru Zhang, Yingping Gai + Show 7 more

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https://doi.org/10.3390/genes13030501

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Journal: Genes	Publication Date: Mar 12, 2022
Citations: 14	License type: CC BY 4.0

Affiliation: Shandong Agricultural University

Abstract

Gamma-aminobutyric acid (GABA) has been reported to accumulate in plants when subjected to salt stress, and GABA-transaminase (GABA-T) is the main GABA-degrading enzyme in the GABA shunt pathway. So far, the salt tolerance mechanism of the GABA-T gene behind the GABA metabolism remains unclear. In this study, the cDNA (designated MuGABA-T) of GABA-T gene was cloned from mulberry, and our data showed that MuGABA-T protein shares some conserved characteristics with its homologs from several plant species. MuGABA-T gene was constitutively expressed at different levels in mulberry tissues, and was induced substantially by NaCl, ABA and SA. In addition, our results demonstrated that exogenous application of GABA significantly reduced the salt damage index and increased plant resistance to NaCl stress. We further performed a functional analysis of MuGABA-T gene and demonstrated that the content of GABA was reduced in the transgenic MuGABA-T Arabidopsis plants, which accumulated more ROS and exhibited more sensitivity to salt stress than wild-type plants. However, exogenous application of GABA significantly increased the activities of antioxidant enzymes and alleviated the active oxygen-related injury of the transgenic plants under NaCl stress. Moreover, the MuGABA-T gene was overexpressed in the mulberry hairy roots, and similar results were obtained for sensitivity to salt stress in the transgenic mulberry plants. Our results suggest that the MuGABA-T gene plays a pivotal role in GABA catabolism and is responsible for a decrease in salt tolerance, and it may be involved in the ROS pathway in the response to salt stress. Taken together, the information provided here is helpful for further analysis of the function of GABA-T genes, and may promote mulberry resistance breeding in the future.

Highlights

Introduction iationsPlants are exposed to a wide array of stresses in their natural surroundings, among which salt stress is a major abiotic stress factor, which has negative effects on plant growth and production
In order to explore whether exogenous Gamma-aminobutyric acid (GABA) affects the salt tolerance of mulberry seedlings, the seedlings treated with 4‰ NaCl were sprayed with GABA for 7 consecutive days
The MDA contents in the leaves were analyzed, and the results showed that the MDA accumulations were increased in all the seedlings under salt stress, but the plants treated with GABA showed significantly lower MDA content than the control ones

Summary

Introduction

Plants are exposed to a wide array of stresses in their natural surroundings, among which salt stress is a major abiotic stress factor, which has negative effects on plant growth and production. In the long evolutionary progress, plants have developed sophisticated mechanisms that attenuate the adverse effects of salt stress. It has been well documented that plants may accumulate compatible solutes, such as carbohydrates and amino acids, which are energy source, osmotic regulants, as well as signaling molecules under saline conditions [3,4]. Among these stress-responsive metabolites, γ-aminobutyric acid (GABA).

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