Glyoxalase I fromBrassica juncea: molecular cloning, regulation and its over‐expression confer tolerance in transgenic tobacco under stress

Abstract

SummaryDespite its ubiquitous presence, the role of glyoxalase I has not been well investigated in plants. In order to find out its physiological functions, we have cloned and characterized a cDNA from Brassica juncea encoding glyoxalase I (Gly I) and made transgenic tobacco plants harbouring Gly I in both sense and antisense orientation. The transgenic nature of the plants was confirmed by Southern blotting, and the estimated number of genes inserted ranged from one to six. The transcript and protein levels of glyoxalase I were also monitored in transgenic plants. The expression of glyoxalase I in B. juncea was upregulated in response to salt, water and heavy metal stresses. In response to a high concentration of salt, the transcript level averaged threefold higher in 72 h, and an increase in the protein was also seen by immunoblotting. The transgenic plants over-expressing glyoxalase I showed significant tolerance to methylglyoxal and high salt, as tested in detached leaf disc senescence assay. A comparison of plants expressing high and low levels of glyoxalase I showed that the tolerance to different salt concentrations was correlated with the degree of glyoxalase I expression. Our results suggest an important role of glyoxalase I in conferring tolerance to plants under stress conditions.

Exogenous Proline and Glycine Betaine Mediated Upregulation of Antioxidant Defense and Glyoxalase Systems Provides Better Protection against Salt-Induced Oxidative Stress in Two Rice (Oryza sativaL.) Varieties

“…Pro- and GB-induced upregulation of glyoxalase enzymes and subsequent salt stress tolerance were also reported by other researchers [29, 32]. Engineering of glyoxalase pathway enzymes in different plant species reduced MG content under salt that was correlated to GSH-based MG detoxification system which reduced oxidative damage [16, 17, 91–93]. These results are in line with our findings.…”

Clustered metallothionein genes are co-regulated in rice and ectopic expression of OsMT1e-Pconfers multiple abiotic stress tolerance in tobacco via ROS scavenging

“…Reports have suggested that although abiotic stress is a multigenic trait, stress tolerant plants could be produced by transgenic approaches by the transfer of a single or multiple genes. Several genes such as barley HVA1 [30], rice CDPK [31], alfalfa Alfin1 [32], tobacco NPK1 [33], and Brassica GlyI and rice GlyII [34-37] have been expressed in transgenic plants to enhance their stress tolerance [38]. …”

Glyoxalase Goes Green: The Expanding Roles of Glyoxalase in Plants

“…Similarly, GLYI expression was significantly upregulated on exposure to salinity, mannitol, and heavy metal stress in Brassica juncea [42]. In pumpkin seedlings, GLYI was upregulated on exposure to white light, salinity, MG, and heavy metal stress [43]; in wheat, upon exposure to ZnCl 2 [44], and in rice, following exposure to arsenite [45].…”

“…In one of the earliest studies, the transformation of tobacco with a GLYI gene from Brassica juncea resulted in transgenic tobacco plants with tolerance to high levels of NaCl and MG [42]. Overexpression of a glyoxalase gene, OsGly I , conferred abiotic stress tolerance to NaCl, ZnCl 2 , and mannitol, and improved grain yield in rice [50].…”