Nonsterol related resistance in Ustilago maydis to the polyene antifungals, amphotericin B and nystatin.

Two amphotericin B resistant mutants of Ustilago maydis were isolated following direct selection from a wild-type population. Each mutant was demonstrated to be cross-resistant to nystatin yet remained sensitive to azoles. Sterol analysis indicated a sterol profile similar to the parent strain, precluding the involvement of an alteration in ergosterol biosynthesis as the cause of polyene resistance.