Production of volatile sesquiterpenes by Fusarium sambucinum strains with different abilities to synthesize trichothecenes

Abstract

Twenty-five strains of Fusarium sambucinum grown on wheat kernels were examined for trichothecene production and the synthesis of volatile sesquiterpenes. The volatiles were purged with air and collected on Tenax traps. Adsorbed compounds were eluted from the traps and injected into a gas chromatograph coupled with a mass spectrometer. Ten strains isolated from potato tubers produced high amounts of diacetoxyscirpenol and its derivatives. These strains were characterized by the production of high amounts of diverse sesquiterpenes. In 10 cultures, 19 compounds were detected, of which 6 were predominant and composed as much as 82% of the volatile sesquiterpene fraction (e.g., beta-farnesene, beta-chamigrene, beta-bisabolene, alpha-farnesene, trichodiene, and an unidentified compound). Fifteen strains isolated from various sources that did not produce trichothecenes produced much less volatile sesquiterpenes, with less chemical diversity. No more than six compounds were present in cultures. Two of these compounds were present in the toxigenic strains isolated from potatoes (beta-farnesene and acoradiene), but four were unique to the strains not producing trichothecenes (longifolene, isocaryophyllene, delta-elemene, and an unidentified one). The pattern of volatile sesquiterpenes was characteristic and distinctive for both toxic and nontoxic strains.