Functional analysis of Transcription Factors containing CCAAT-DNA Binding domain in Fusarium graminearum

Abstract

The homothallic ascomycete fungus Fusarium graminearum is an important plant pathogen of major cereal crops. The CCAAT sequence is present in roughly 30% of eukaryotic promoters. In filamentous fungi, the CCAAT sequence has been known to modulate the expression of several critical genes involved in various developmental stages. Eight transcription factors (TFs) containing CCAAT-DNA binding domain (FCT1~8) are in F. graminearum. Among them, we chose 2 TF mutants, ∆fct1 and ∆fct3, that have similar pleiotropic defects from a previously generated TF mutant library. Both deletion mutants have similar defects in mycelia growth, sexual reproduction, and virulence. Double deletion of FCT1 and FCT3 resulted in indistinguishable phenotypes compared to each single deletion mutant. Moreover, Fct1 and Fct3 physically interacted with each other and localized to nuclei, suggesting that Fct1 and Fct3 form protein complex for transcriptional regulation. This is the first study dealing with TFs containing CCAAT DNA-binding domain in plant pathogenic fungi and present weighty perception to understand molecular mechanisms underlying functions of CCAAT-binding factors in F. graminearum.