Abstract
Cell cycle regulation and the maintenance of genome integrity are crucial for the development and virulence of the pathogenic plant fungus Fusarium graminearum. To identify transcription factors (TFs) related to these processes, four DNA-damaging agents were applied to screen a F. graminearum TF mutant library. Sixteen TFs were identified to be likely involved in DNA damage responses. Fhs1 is a fungal specific Zn(II)2Cys6 TF that localises exclusively to nuclei. fhs1 deletion mutants were hypersensitive to hydroxyurea and defective in mitotic cell division. Moreover, deletion of FHS1 resulted in defects in perithecia production and virulence and led to the accumulation of DNA damage. Our genetic evidence demonstrated that the FHS1-associated signalling pathway for DNA damage response is independent of the ATM or ATR pathways. This study identified sixteen genes involved in the DNA damage response and is the first to characterise the novel transcription factor gene FHS1, which is involved in the DNA damage response. The results provide new insights into mechanisms underlying DNA damage responses in fungi, including F. graminearum.
Highlights
DNA functions as the carrier of genetic information, and genome integrity and stability are essential for all organisms
Experimental conditions were established such that the F. graminearum wild-type strain exhibited approximately one half of the radial growth observed on complete medium (CM) without any DNA-damaging agent: methyl methanesulfonate (MMS, 0.1 μ l/ml), hydroxyurea (HU, 10 mM), bleomycin (BLM, 10 mU/ml), and camptothecin (CPT, 0.4 μ M)
The construction of a transcription factor (TF) mutant library shed light on fungal genetics, because transcription factors (TFs) are thought to be involved in most biological processes[11]
Summary
DNA functions as the carrier of genetic information, and genome integrity and stability are essential for all organisms. If left unrepaired or incorrectly repaired, damaged DNA will result in cell cycle arrest, cell death, loss of genetic information, and genomic instability[2]. DDR ensures the maintenance of genome integrity and stability by regulating DNA repair mechanisms. Various forward and reverse genetic approaches have been applied in F. graminearum; most of the previous studies have focused on signal transduction pathways or orthologous genes, which tend to be highly conserved in eukaryotes[7,9,10]. Because TFs are involved in most biological processes, screening the TF mutant library with specific stress conditions will shed light on novel mechanisms for these processes. The identification of TFs related to DNA damage responses could uncover novel mechanisms in F. graminearum
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