Trichoderma versus Fusarium—Inhibition of Pathogen Growth and Mycotoxin Biosynthesis

This study evaluated the ability of selected strains of Trichoderma viride, T. viridescens, and T. atroviride to inhibit mycelium growth and the biosynthesis of mycotoxins deoxynivalenol (DON), nivalenol (NIV), zearalenone (ZEN), α-(α-ZOL) and β-zearalenol (β-ZOL) by selected strains of Fusarium culmorum and F. cerealis. For this purpose, an in vitro experiment was carried out on solid substrates (PDA and rice). After 5 days of co-culture, it was found that all Trichoderma strains used in the experiment significantly inhibited the growth of Fusarium mycelium. Qualitative assessment of pathogen–antagonist interactions showed that Trichoderma colonized 75% to 100% of the medium surface (depending on the species and strain of the antagonist and the pathogen) and was also able to grow over the mycelium of the pathogen and sporulate. The rate of inhibition of Fusarium mycelium growth by Trichoderma ranged from approximately 24% to 66%. When Fusarium and Trichoderma were co-cultured on rice, Trichoderma strains were found to inhibit DON biosynthesis by about 73% to 98%, NIV by about 87% to 100%, and ZEN by about 12% to 100%, depending on the pathogen and antagonist strain. A glycosylated form of DON was detected in the co-culture of F. culmorum and Trichoderma, whereas it was absent in cultures of the pathogen alone, thus suggesting that Trichoderma is able to glycosylate DON. The results also suggest that a strain of T. viride is able to convert ZEN into its hydroxylated derivative, β-ZOL.