mutants blocked or altered in the production of the trichothecene mycotoxin t - 2 have been selected following uv mutagenesis of fusarium sporotrichioides nrrl 3299 . one mutant , nrrl 18339 , accumulates the rare trichothecenes dideacetylcalonectrin and deacetylcalonectrin . the second mutant , nrrl 18340 , accumulates trichodiene , the first intermediate on the trichothecene biosynthetic pathway . these compounds are useful toxins or toxic precursors for the production of or investigation of immunotoxins for cancer therapy .