Nitric Oxide and Dimethylthiourea Up-regulates Pyrroline-5-Carboxylate Synthetase Expression to Improve Arsenic Tolerance in Glycine max L.

Arsenic (As) is a toxic metalloid, severely affecting the normal functioning of plants, animals, and human beings. Nitric oxide (NO) and dimethylthiourea (DMTU) are two potential compounds play key roles in enhancing tolerance against a variety of abiotic stresses in plants. In the present study, ameliorating abilities of both NO and DMTU against As-induced disturbances in Glycine max L. have been investigated. Overall results revealed that As accrual significantly suppressed seed germination, radicle length, and biomass accumulation. The oxidative stress markers such as membrane integrity, contents of reactive oxygen species, and malondialdehyde, and lipoxygenase activity were enhanced by As treatment. Pronounced decreases in protein and DNA contents with a concomitant increase in DNA oxidation were observed in the growing radicles after exposure to As. In addition, treatment of As also revealed elevation in the activity and gene expression of pyrroline-5-carboxylate synthetase, in parallel to both proline and sugar accumulation. However, the toxic effects of As were partially/to a large extent reversed by the exogenous application of NO and DMTU, separately, in Glycine max L. Moreover, between these two treatments, NO was more efficient than the DMTU against As-induced oxidative stress responses in Glycine max L. Our findings provide a foundation to minimize the toxic effects of As in crop plants worldwide. (C) 2018 American Institute of Chemical Engineers