No abstract

The authors assayed the ability of some reaction products, essentially isothiocyanates, derived from the myrosinase-catalysed hydrolysis (neutral pH) of six natural glucosinolates to inhibit germination and mycelial growth of Botrytis cinerea, Rhizopus stolonifer, Monilinia laxa, Mucor piriformis and Penicillium expansum, the leading postharvest fungal pathogens of fruit and vegetable crops. All of the tested products showed antifungal activity, although they proved less effective against mycelial growth than in germination control. The isothiocyanates produced by enzymatic hydrolysis of glucoraphenin, sinalbin and sinigrin were particularly effective because they completely inhibited conidic germination of all five pathogens considered. The sinigrin-derived isothiocyanate exhibited a wide pathogen-control spectrum, either inhibiting conidia germination altogether or delaying by 3-6 days the onset of mycelial growth compared to the control.

The present study assayed the effect of six isothiocyanates (ITCs), produced by the enzymatic hydrolysis of glucosinolates, on fungal pathogens of pear. Sample pear fruits were artificially inoculated through induced wounds with conidial suspensions of Botrytis cinereaRhizopus stoloniferMonilinia laxaMucor piriformis or Penicillium expansum and were then treated with ITCs. Of the six ITCs tested, the ITC from glucoraphenin showed the highest effectiveness after 6 days at 20°C, against M. laxaB. cinerea and M. piriformis. The effectiveness of the ITC from glucoraphenin against M. laxa was assayed in two further trials to test the effect of ITC concentration on different concentrations of inoculum and to determine the duration of the curative effect of this ITC. ITC concentration directly affected fungus control capacity. The highest ITC concentration (3.6 mg mL−1) afforded pathogen control at the highest level of pathogen concentration (106 conidia mL−1) after 6 days at 20°C. Its curative effect was evident up to 40 h after inoculation.

No abstract