Selenium enrichment alters Trichoderma spp. antagonistic activity against phytopathogenic fungi

Abstract

Trichoderma harzianum DEMf 1V and Тrichoderma citrinoviride DEMf: TR3 are confirmed biocontrol agents used in this study to estimate the effects of selenium enrichment on their antifungal activity. Se-enriched cultures were prepared by growing on potato-dextrose broth supplemented with 2.5 and 5 mg Se/L added in the form of Na2SeO3. The antifungal activity of Se-enriched and control cultures was estimated by their ability to produce hydrolytic enzymes, which were detected using API ZYM, cellulase and protease tests. The antagonistic potential and impact of volatile compounds were observed in interactions with Botrytis cinerea, Fusarium oxysporum, and Fusarium graminearum. In Se-enriched T. harzianum DEMf 1V, the production of esterase, lipase, and N-acetyl-β-glucosaminidase was inhibited, while in Se-enriched Т. citrinoviride DEMf: TR3, only lipase production was interrupted. All cultures maintained the ability to produce cellulase and protease. Cultures of T. harzianum DEMf 1V grown with and without Se enrichment exhibited a high inhibition rate against B. cinerea (68–74%) and F. oxysporum (62–70%). The antagonistic activity of Se-enriched T. harzianum DEMf 1V against F. graminearum (65–66%) was higher compared to the control (60%). Se-enriched Т. citrinoviride DEMf: TR3 expressed lower inhibition against B. cinerea and F. graminearum compared to the control. Volatile compounds caused a low level of inhibition, indicating that they are among the antifungal mechanisms employed by the isolates, but not the dominant one. Further research should be directed towards the precise determination of metabolic changes induced by Se enrichment and the implications thereof for Trichoderma's antagonistic activities.