Investigation on the protective role of nitric oxide in alleviating arsenic acid toxicity in shoot and root of Ocimum basilicum L.

Nitric oxide (NO) is a highly reactive free radical with a wide variety of physiological implications in plants. In this research، we investigated the protective effects of exogenous Sodium Nitroprusside (SNP) as a NO donor، against the toxicity caused by excess arsenic in sweet basil (Ocimum basilicum L.). Seedlings grown in a Hoagland nutrient solution were treated with SNP at 0 (control) and 150 µM and different concentration of arsenate at 0 (control)، 150 and 300 µM. Arsenic treatment (specially in 300 µM) significantly induced accumulation of hydrogen peroxide (H2O2) significantly increase in serious lipid peroxidation، electrolyte leakage (EL) and decreased the growth and the biomass of basil. Application of SNP before arsenic stress resulted in alleviated arsenic-induced electrolyte leakage and malondiadehyde (MDA) content and increased proline and free amino acid contents in shoots and roots of sweet basil، compared with the control. On the whole، our results showed stronger arsenic toxicity in the root than in the shoot and nitric oxide probably، was increased tolerance capacity in basil due to production of osmoprotecting compounds such as proline، sugar and free amino acid. In addition، analysis of ICP-results indicated that، As translocation from root to shoot of O. basilicum was limited by SNP pretreatment which is very important for human health.