Activation of defense responses under isothiocyanate stress in oilseed rape plantlets

In this study، the hypothesis that defense response in leaves of the oilseed rape is induced under isothiocyanate stress was investigated. The effects of different concentrations of of methyl and propyl isothiocyanates (0، 1، 10 and 100 mM) were evaluated on accumulation of hydrogen peroxide، phenolic compound content and PAL and GST enzymes activities in Brassica napus L. Oxidative stress in isothiocyanates treated oilseed rape plantlets was deduced from increment of percentage of electrolyte leakage and from accumulation of hydrogen peroxide. Results showed that the PAL activity was significantly correlated to the contents of phenolic compounds in response to isothiocyanates. Results also showed that GST activity was induced in oilseed rape plantlets in response to exposure to 1mM isothiocyanate. Results suggested that production of total phenolic compound was not the only means of detoxifying in the oilseed rape plantlets and glutathione conjugation was also involved in the defense response to toxification in oilseed rape.