Resistance to cyanide by salicylate pretreatment in Salix babylonica L.

Abstract

Cyanide is uncontrollably produced in some industrial operations and has lethal effects on humans and the environment. Since removing processes of cyanide are complicated and costly, the phytoremediation has recently been extensively considered. To achieve an increased cyanide resistance, which is needed for an efficient phytoremediation of the mediums with high concentrations of cyanide, the effects of salicylate as a phytohormone were studied. Cuttings of Salix babylonica, as a model plant, were used in a completely randomized design with three replicates in hydroponics using a modified Hoagland nutrient solution. Plants were pretreated with sulfosalicylate (0, 5, 10 and 15 mg L-1) for 21 days and then were treated with toxic concentration of cyanide (9 mg CN- L-1); some of the physiological indices which show cyanide toxicity/resistance were measured. Favorable responses to salicylate toward the increase in resistance to cyanide were concentration dependent which were observed at 10 mg L-1 sulfosalicylate and it was accompanied with an increase in superoxide dismutase activity and reducing the capacity of root extract. Dehydrogenase activity and electrolyte leakage from roots were decreased relating to control plants. It also prevented the cyanide inhibitory effect on oxygen consumption. The observed effects could be attributed to redox status and alteration of production and scavenging of reactive oxygen species by salicylate and cyanide. The results indicated that a proper concentration of salicylate could be used as a cyanide resistance stimulator in willows.