Toxicity of hydrolysis volatile products of 'Brassica' plants to 'Sclerotinia sclerotiorum', in vitro

Oilseed rape stem rot disease caused by 'Sclerotinia sclerotiorum' causes serious yield losses worldwide. Glucosinolates as specific secondary metabolites of 'Brassicaceae' are produced in various parts of the host plants. Their enzymatic hydrolysis releases chemical components, particularly isothiocyanates, with fungitoxic activity and volatile characteristics. To investigate the effect of volatiles derived from 'Brassica' tissues, the pathogen was exposed to hydrolysis products of 'Brassica' shoot parts as sources of glucosinolates including oilseed rape varieties and two species, black and white mustard. The results showed significant differences in inhibition of 'S. sclerotiorum' growth between varieties and species. All tissues of black mustard inhibited completely the exposed colonies of the pathogen and oilseed rape varieties Dunkeld, Oscar and Rainbow had significant inhibitory effect on the fungus. The genotypes demonstrated significant differences for the production of toxic volatiles, indicating that GSL contents in Brassica species and even cultivars have different potentials for toxic products.