Dimethylthiourea antagonizes oxidative responses by up-regulating expressions of pyrroline-5-carboxylate synthetase and antioxidant genes under arsenic stress
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Dimethylthiourea is an important plant growth regulator that mediates various physiological and metabolic processes of the plants. In the present study, role of dimethylthiourea in conferring arsenic stress tolerance to Cajanus cajan L. was investigated. Exposure to arsenic resulted in oxidative damage as evidenced by decreased germination percentage, radicle length, biomass accumulation, membrane stability index, protein, glyoxalase I and II, and antioxidants, together with enhanced cell death, reactive oxygen species, lipid peroxidation and activity of lipoxygenase in C. cajan L. However, exogenous application of dimethylthiourea along with arsenic decreased the reactive oxygen species and lipoxygenase activity, while increased the membrane stability index and antioxidants activities. Moreover, dimethylthiourea also up-regulated the glyoxalase (I and II) activity and the gene expression of antioxidants under arsenic stress. Also, dimethylthiourea application reduced the arsenic content than that measured in arsenic alone treated samples. Interestingly, treatment of dimethylthiourea uplifted the contents of ascorbic acid and glutathione, together with proline via up-regulating the activity and gene expression of pyrroline-5-carboxylate synthetase, one of the chief enzymes of its biosynthetic pathway. Enlisted findings suggested that dimethylthiourea can improve plant resistance to arsenic toxicity by regulating the gene expression of antioxidants and proline biosynthesizing enzymes, thereby reducing reactive oxygen species, lipid peroxidation and arsenic accumulation.
KeywordsCajanus cajan L. Cell death Gene expression Glyoxalase system Lipoxygenase Proline Reactive oxygen species
The authors would also like to thank Defense Research and Development Organization, New Delhi (DRDE/TC/05414/Proj/TASK-220/16 Dated June 27, 2016) and Department of Science and Technology, New Delhi (No. DST/INSPIRE Fellowship/2013/791, dated 23.01.2013) for providing research facilities for this study. Authors are also grateful to Department of Science and Technology, New Delhi, for financial support through DST-FIST scheme (Sanction No. 2384/IFD/2014-15, dated 31.07.2014) sanctioned to the School of Studies in Biotechnology.
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