Nitric oxide mediated regulation of ascorbate-glutathione pathway alleviates mitotic aberrations and DNA damage in Allium cepa L. under salinity stress

STATEMENT OF NOVELTY Allium cepa L. response to salt stress has been investigated but its role on chromosomal changes and DNA damage are less investigated therefore, our focus is to explore NO supplementation effects on cytological aberrations and biochemical responses in A. cepa L. roots under salinity stress. Allium cepa L. is an important medicinal and food plant enormously affected by salinity in terms of its growth and quality. This experiment investigates ameliorative potential of NO donor sodium nitroprusside (SNP) on chromosomal aberrations and physiological parameters in A. cepa L. roots exposed to salinity stress. Roots with different concentrations of NaCl (25, 50, and 100 mM) alone, and in combination with 100 mu M SNP were analyzed for mitotic aberrations, DNA damage, proline, malondialdehyde (MDA) content, and ascorbate-glutathione (AsA-GSH) cycle after 120 h of salinity treatments. Results revealed that salinity stress increased chromosomal aberrations, MDA, proline accumulation, and severely hampered the AsA-GSH cycle function. The comet assay revealed a significant (p <= 0.05) enhancement in tail length (4.35 +/- 0.05 mu m) and olive tail moment (3.19 +/- 0.04 mu m) at 100 mM NaCl exposure. However, SNP supplementation decreased total percent abnormalities, while increased the prophase, metaphase, anaphase, and telophase indexes. Moreover, ascorbate peroxidase and glutathione reductase activities increased with AsA/DHA and GSH/GSSG ratios, respectively. Results suggest that SNP supplementation alleviates salinity stress responses by improving AsA-GSH cycle and proline accumulation. Based on present findings, NO supplementation could be recommended as a promising approach for sustainable crop production under salinity stress.