A glutathione‐independent DJ‐1/PfpI domain‐containing tomato glyoxalaseIII2, SlGLYIII2, confers enhanced tolerance under salt and osmotic stresses

Abstract

In plants, glyoxalase enzymes are activated under stress conditions to mitigate the toxic effects of hyperaccumulated methylglyoxal (MG), a highly reactive carbonyl compound. Until recently, a glutathione-dependent bi-enzymatic pathway involving glyoxalase I (GLYI) and glyoxalase II (GLYII) was considered the primary MG-detoxification system. Recently, a new glutathione-independent glyoxalase III (GLYIII) mediated direct route was also reported in plants.However, the physiological significance of this new pathway remains to be elucidated across plant species. This study identified the full complement of 22 glyoxalases in tomato. Based on their strong induction under multiple abiotic stresses, SlGLYI4, SlGLYII2 and SlGLYIII2 were selected candidates for further functional characterisation. Stress-inducible overexpression of both glutathionedependent (SlGLYI4 + SlGLYII2) and independent (SlGLYIII2) pathways led to enhanced tolerance in both sets of transgenic plants under abiotic stresses.However, SlGLYIII2 overexpression (OE) plants outperformed the SlGLYI4 + SlGLYII2 OE counterparts for their stress tolerance under abiotic stresses.Further, knockdown of SlGLYIII2 resulted in plants with exacerbated stress responses than those silenced for both SlGLYI4 and SlGLYII2. The superior performance of SlGLYIII2 OE tomato plants for better growth and yield under salt and osmotic treatments could be attributed to better GSH/GSSG ratio, lower reactive oxygen species levels, and enhanced antioxidant potential, indicating a prominent role of GLYIII MG-detoxification pathway in abiotic stress mitigation in this species.

Methylglyoxal detoxifying gene families in tomato: Genome-wide identification, evolution, functional prediction, and transcript profiling

“…A similar phenomenon was observed in Medicago , in which all of the MtDJ-1 members were expressed under salinity stress along with other stress conditions [ 60 ]. A recent investigation into tomato glyoxalase III (GLYIII) genes revealed that their overexpression enhances salt and osmotic stress tolerance, contributing positively to plant growth and yield [ 68 ]. Further, transgenic tobacco expressing E .…”

Linking the key physiological functions of essential micronutrients to their deficiency symptoms in plants

“…MG induces cellular damage by spontaneously glycating nucleic acids, proteins and lipids. In plants, there are three classes of GLY enzymes – GLYI, GLYII, and GLYIII – among which GLYI and GLYII are glutathione (GSH) and metal cofactor dependent, while GLYIII are GSH‐ and metal ion‐independent enzymes detoxifying MG (Schmitz et al ., 2017; Gambhir et al ., 2023). While GLYI enzymes use Zn as a cofactor in all other eukaryotes, plants have both Zn‐type and Ni‐type GLYI enzymes (Balparda et al ., 2023).…”

Genome-wide analysis and expression profiling of glyoxalase gene families in oat (Avena sativa) indicate their responses to abiotic stress during seed germination

“…GLX3, a novel glyoxalase enzyme of the DJ-I protein family, directly catalyzes the conversion of MG to D-lactate ( Ghosh et al., 2016 ). Only a few studies have investigated GLX3 in model plants and cereal crops, demonstrating its participation in stress responses ( Jana et al., 2021 ; Kumar et al., 2021 ; Gambhir et al., 2023 ). Recent studies have shown that GLX1 and GLX2 are also involved in regulating seed vigor in Oryza sativa and Arabidopsis ( Schmitz et al., 2017 ; Liu et al., 2022 ), but their role in seed development, storage, and germination is still poorly understood.…”