Arsenic-induced genotoxic responses and their amelioration by diphenylene iodonium, 24-epibrassinolide and proline in Glycine max L.

Presence of the toxic metalloid, "arsenic (As)" is ubiquitous in the environment especially in the soil and water. Its excess availability in the soil retards growth and metabolism of plants via (a) slowing down the cell division/elongation, (b) overproduction of reactive oxygen species (ROS), (c) modulation of antioxidant enzymes, and (d) alteration of DNA profile/genomic template stability (GTS). In the current study, diphenylene iodonium (DPI), 24-epibrassinolide (EBL) and proline (Pro) were used to analyze their roles in eliminating the adverse effects of As. Glycine max L. (variety JS 335) seeds were subjected to As (75 μM, Sodium arsenite was used as source of As), and in combination with DPI (10 μM), EBL (0.5 μM) or Pro (10 mM), for five consecutive days, and effects of these treatment combinations were analyzed on germination percentage, biomass, membrane stability, GTS and expressions of defensive genes. In addition, the levels of As, ROS, malondialdehyde, DNA content, oxidation, fragmentation, polymorphism, DNase activity, endogenous Pro and pyrroline-5-carboxylate synthetase activity were evaluated. The results indicated that the treatments of DPI, EBL or Pro are capable to alleviate detrimental effects of As, gauged from above variables, but with different magnitudes. Apropos As-stress mitigation, Pro was found to be the most effective under the confines of the study protocol. This study certainly provides new ideas for intensifying studies to unravel elusive central mechanism of amelioration involving use of DPI, EBL or Pro in plants with confirmed As-toxicity.