Effect of Compactin on the Mycotoxin Production and Expression of Related Biosynthetic and Regulatory Genes in Toxigenic <i>Fusarium culmorum</i>

Zearalenone (ZEN) and deoxynivalenol (DON) are mycotoxins produced by various species of <i>Fusarium</i> fungi. They contaminate agricultural products and negatively influence human and animal health, thus representing a serious problem of the agricultural industry. Earlier we showed that compactin, a secondary metabolite of <i>Penicillium citrinum</i>, is able to completely suppress the aflatoxin B1 biosynthesis by <i>Aspergillus flavus.</i> Using the <i>F. culmorum</i> strain FC-19 able to produce DON and ZEN, we demonstrated that compactin also significantly suppressed both DON (99.3%) and ZEN (100%) biosynthesis. The possible mechanisms of this suppression were elucidated by qPCR-based analysis of expression levels of 48 biosynthetic and regulatory genes. Expression of eight of 13 <i>TRI</i> genes, including <i>TRI4</i>, <i>TRI5</i>, and <i>TRI101</i>, was completely suppressed. A significant down-regulation was revealed for the <i>TRI10</i>, <i>TRI9</i>, and <i>TRI14</i> genes. <i>TRI15</i> was the only up-regulated gene from the TRI cluster. In the case of the ZEN cluster, almost complete suppression was observed for <i>PKS4</i>, <i>PKS13</i>, and <i>ZEB1</i> genes, and the balance between two <i>ZEB2</i> isoforms was altered. Among regulatory genes, an increased expression of <i>GPA1</i> and <i>GPA2</i> genes encoding α- and β-subunits of a G-protein was shown, whereas eight genes were down-regulated. The obtained results suggest that the main pathway for a compactin-related inhibition of the DON and ZEN biosynthesis affects the transcription of genes involved in the G-protein-cAMP-PKA signaling pathway. The revealed gene expression data may provide a better understanding of genetic mechanisms underlying mycotoxin production and its regulation.