Zn2+dependent glyoxalase I plays the major role in methylglyoxal detoxification and salinity stress tolerance in plants.

Rituraj Batth,Sumita Kumari,Preeti Nagar,Ashish Kumar,Ananda Mustafiz,Muskan Jain,Mohammad Ansari

doi:10.1371/journal.pone.0233493

Abstract

Glyoxalase pathway is the major pathway of methylglyoxal detoxification and is ubiquitously present in all organisms ranging from prokaryotes to eukaryotes. Glyoxalase I (GLYI) and Glyoxalase II (GLYII), the two core enzymes of this pathway work together to neutralize methylglyoxal (MG), a dicarbonyl molecule with detrimental cytotoxicity at higher concentrations. The first step towards the detoxification of MG is catalyzed by GLYI, a metalloenzyme that requires divalent metal ions (either Zn2+ as seen in eukaryotes or Ni2+ as in prokaryotes). However, both Zn2+ and Ni2+ dependent GLYIs have been shown to co-exist in a higher eukaryote i.e. Arabidopsis thaliana. In the present study, we determine the role of both Zn2+ dependent (AtGLYI2) and Ni2+ dependent (AtGLYI3, AtGLYI6) GLYIs from Arabidopsis in salinity stress tolerance. AtGLYI2 overexpressing Arabidopsis plants showed better growth rate while maintaining lower levels of MG under high saline conditions. They were taller with more number of silique formation with respect to their Ni2+ dependent counterparts. Further, lack in germination of Arabidopsis AtGLYI2 mutants in presence of exogenous MG indicates the direct involvement of Zn2+ dependent GLYI in MG detoxification, suggesting Zn2+ dependent GLYI as the main enzyme responsible for MG detoxification and salinity stress tolerance.

Highlights

Methylglyoxal (MG) is a dicarbonyl molecule produced as a by-product of various metabolic pathways such as glycolysis, lipid peroxidation and amino acid metabolism
AtGLYI2, AtGLYI3 and AtGLYI6 gene overexpressing single insertion homozygous transgenic lines were screened to confirm the insertion of T-DNA in the genome of Arabidopsis thaliana plant (Fig 1A)
The amplified PCR products showed the presence of approximately 558 bp, 853 bp and 1053 bp bands for AtGLYI2, AtGLYI3 and AtGLYI6 genes from respective transgenic plants and no amplified DNA fragment from wild-type plants confirmed the insertion of T-DNA fragment into the genome of Arabidopsis thaliana (Fig 1B)

Summary

Introduction

Methylglyoxal (MG) is a dicarbonyl molecule produced as a by-product of various metabolic pathways such as glycolysis, lipid peroxidation and amino acid metabolism. Levels of MG have been found to increase by 2–6 folds in response to abiotic stresses in plant system [1]. At higher concentration, it acts as a potent cytotoxic molecule which reacts with major macromolecules to forms advanced glycation end products [2] and causes inactivation of proteins and leads to oxidative damage of cellular components [3]. Glyoxalase system plays a major role in detoxification of MG. It consists of two main enzymes, glyoxalase I (GLYI) and glyoxalase II (GLYII).

Methods

Results

Conclusion