Effects of nitric oxide on alleviating cadmium stress in Typha angustifolia

Nitric oxide (NO) is a key signal molecule that is involved in plant response to various abiotic stresses. The present study was conducted to investigate the effects of NO on Typha angustifolia which has been subjected to cadmium stress. Our results showed that sodium nitroprusside (SNP, a NO donor) treatment could significantly mitigate both the Cd (CdCl2 center dot 2.5H(2)O)-induced increase of malondialdehyde content in the root and relative electrolyte leakage in the root and leaf. NO demonstrated a reduced or counteractive effect on the Cd-induced increase in the activities of some typical antioxidant enzymes. The Cd-induced changes on the contents of non-protein thiol and phytochelatins in the root could also be reversed by NO. The protected effect of NO is likely achieved through trapping Cd in the root and decreasing Cd accumulation in the leaf and sheath. Furthermore, NO enhanced the allocation of Cd in the cell wall and reduced the distribution of Cd in the soluble fraction of the root and leaf. Differential biosynthesis of ascorbic acid content in some tissues might also be responsible for the protected effect of NO. This study concludes that NO counteracts Cd toxicity strongly in T. angustifolia via regulating antioxidant metabolism and enhancing Cd accumulation in the cell wall of the root.