Biochemical Mechanisms of Mimosine Toxicity to Sclerotium rolfsii Sacco

Abstract

Mimosine when added at a final concentration of 2·5 mM to potato dextrose broth reduced the mycelial growth of S. rolfsii by 40-60 % and prevented the formation of sclerotia. This inhibitory action of mimosine was alleviated by 80 % by 5 mM pyridoxal-5-phosphate and by 50 % by tryptophan and 5 mM tyrosine. Phenylalanine had little effect. Among the metal ions, Fe3 + at 10 mM most effectively decreased mimosine's inhibitory effect by 93 %, AI3 + at 5 mM decreased it by 80 % while Fe2+ and Cu2 + at 5 mM exhibited the least effect (about 25 and 9 %, respectively).