Manipulation of glyoxalase pathway confers tolerance to multiple stresses in rice

Abstract

Crop plants face a multitude of diverse abiotic and biotic stresses in the farmers' fields. Although there now exists a considerable knowledge of the underlying mechanisms of response to individual stresses, the crosstalk between response pathways to various abiotic and biotic stresses remains enigmatic. Here, we investigated if the cytotoxic metabolite methylglyoxal (MG), excess of which is generated as a common consequence of many abiotic and biotic stresses, may serve as a key molecule linking responses to diverse stresses. For this, we generated transgenic rice plants overexpressing the entire two-step glyoxalase pathway for MG detoxification. Through assessment of various morphological, physiological and agronomic parameters, we found that glyoxalase-overexpression imparts tolerance towards abiotic stresses like salinity, drought and heat and also provides resistance towards damage caused by the sheath blight fungus (Rhizoctonia solani) toxin phenylacetic acid. We show that the mechanism of observed tolerance of the glyoxalase-overexpressing plants towards these diverse abiotic and biotic stresses involves improved MG detoxification and reduced oxidative damage leading to better protection of chloroplast and mitochondrial ultrastructure and maintained photosynthetic efficiency under stress conditions. Together, our findings indicate that MG may serve as a key link between abiotic and biotic stress response in plants.

From methylglyoxal to pyruvate: a genome-wide study for the identification of glyoxalases and D-lactate dehydrogenases in Sorghum bicolor

“…Therefore, it would not be inappropriate to term MG and glyoxalases as possible biomarkers of plant stress tolerance [15]. To this end, over-expression of glyoxalase pathway genes has been carried out in various plant species wherein through improved MG detoxification as a result of increased activity of glyoxalase pathway enzymes, MG levels could be restricted from rising under stress, thereby imparting enhanced stress tolerance to plants [33,[35][36][37][38]. Previous genome-wide studies carried out in Arabidopsis, Oryza sativa [18], Glycine max [19], Medicago truncatula [20] and Brassica rapa [21] have identified the presence of glyoxalase pathway genes as multiple members in these plant species and shown them to be differentially regulated in response to various abiotic stresses.…”

Potential of exogenously sourced kinetin in protecting Solanum lycopersicum from NaCl-induced oxidative stress through up-regulation of the antioxidant system, ascorbate-glutathione cycle and glyoxalase system

“…Higher concentrations of GSH in KN treated plants may have contributed significantly to the maintenance of the glyoxylase system for elimination of methylglyoxal, which may decline the chances of any serious genotoxic effect [72]. Glyoxylase I and II form the key enzymatic components of the glyoxylase system, and KN-induced up-regulation in their activities, accompanied by the increased GSH, may have led to exploit the beneficial effects of methylglyoxal like crosstalk with important signaling molecules like Ca, ROS and ABA [73].…”

“…For example, in salt stressed rice, Rahman et al [12] have also demonstrated up-regulation of the glyoxylase system. Enhanced activity of the glyoxylase system due to exogenous application of KN may have protected the electron transport system by preventing damage to chloroplast and mitochondrial ultrastructures [72]. …”

Genome-wide analysis of glyoxalase-like gene families in grape (Vitis vinifera L.) and their expression profiling in response to downy mildew infection

“…The role of the glyoxalase system in resistance to multiple biotic and abiotic stresses has been well characterised in some studies. Recently, it has been reported that the glyoxalase pathway of rice not only increases tolerance to salinity, drought and extreme temperatures but also reduces damage from sheath blight fungus (Rhizoctonia solani) [69]. Moreover, some glyoxalase members of soybean such as GmGLYI-6/9/20 and GmGLYII-6/10 show special expression patterns in response to various pathogenic infection [9].…”