Accumulation of anthraquinones in the reddish brown-colored polyoxin-resistant mutants of Cochliobolus heterostrophus

Abstract

Cochliobolus heterostrophus Pol2 and Pol5 mutants are pleiotropic, and each mutant gene is responsible for alterations of both unrelated phenotypes: reddish-brown pigmentation and polyoxin resistance. The three pigments accumulated in these mutants were isolated. Structural characterization by spectroscopic analyses indicated that these three pigments were polyhydroxyanthraquinones: emodin, chrysophanol, and citreorosein. Emodin is known to be an antidote against benzimidazole fungicide, although no antidoting activity against polyoxin was observed.