Estrogenic Compounds Compatible with a Conditional Gene Expression System for the Phytopathogenic Fungus Fusarium graminearum

The ascomycete fungus Fusarium graminearum is an important plant pathogen responsible for Fusarium head blight in small grains and ear rot on maize. This fungus also produces the estrogenic metabolite, zearalenone (ZEA) that causes estrogenic disorders in humans and animals. Previously, we developed a conditional gene expression system for this fungus using a ZEA-inducible promoter (Pzear). In the present study, four other estrogenic compounds, including ${\beta}$-estradiol, estriol, estrone, and secoisolariciresinol, were screened as possible substitutes for ZEA in this system. Among them, ${\beta}$-estradiol was able to successfully induce the expression of a gene controlled by Pzear, while estrone was only able to partially induce its expression but the other two compounds were not effective. In combination, these results demonstrate that ${\beta}$-estradiol can replace ZEA in this conditional gene expression system, thereby eliminating the need to use the more expensive reagent, ZEA, and facilitating high-throughput functional analyses of F. graminearum in future studies.