|VILLANI, ALESSANDRA - National Research Council - Italy|
|SUSCA, ANTONELLA - National Research Council - Italy|
|MORETTI, ANTONIO - National Research Council - Italy|
Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: 4/11/2018
Publication Date: 4/11/2018
Citation: Brown, D.W., Villani, A., Susca, A., Moretti, A., Proctor, R., McCormick, S.P., Kim, H. 2018. Novel Zn(II)2Cys6 transcription factor in Fusarium equiseti trichothecene gene cluster is a pathway specific and global regulator [abstract].
Technical Abstract: Trichothecenes are among the mycotoxins of greatest concern to food and feed safety and are produced by at least two lineages of Fusarium: the F. sambucinum (FSAMSC) and F. incarnatum-equiseti (FIESC) species complexes. Trichothecene biosynthesis begins with the formation of a cyclic sesquiterpene from the isoprenoid farnesyl pyrophosphate (FPP) followed by up to eight oxygenation and four acylation reactions. Most trichothecene biosynthetic genes (TRI) are co-regulated and located in a cluster. All Fusarium TRI clusters characterized to date include two regulatory genes: TRI6 and TRI10, which encode a C2H2 zinc finger and a fungal transcription factor domain, respectively. Functional analysis of FSAMSC members indicate that TRI6 is required for wild-type expression of all genes involved in synthesis of the trichothecene deoxynivalenol (DON), except TRI10, and eight genes involved in FPP synthesis while TRI10 regulates TRI6 expression, and to a lesser degree, all eight FPP genes. Here, we characterized a new gene, TRI21, located in the TRI cluster of FIESC but not FSAMSC, that encodes a Zn2Cys6 transcription factor protein. Gene deletion and precursor feeding studies indicate that TRI21 is required for function of two TRI cluster genes (TRI11 and TRI13) responsible for the last two oxygenation reactions required for synthesis of the trichothecene 4,15-diacetoxyscripenol (DAS), but not for function of other cluster genes. RNA-Seq analysis indicated that TRI21 is required for wild-type expression of 10 of 14 FIESC TRI cluster genes as well as six of the eight FPP genes. These results indicate fundamental differences in the regulation of the TRI cluster in FIESC and FSAMSC. Furthermore, the presence of a pseudogenized TRI21 in some members of FSAMSC indicates that the evolution of TRI cluster regulation in FSAMSC has included loss of TRI21 and extension of TRI6 function.