Molecular characterization of Zn(II)2Cys6 cluster gene family and their association with pathogenicity of the onion basal rot pathogen, Fusarium oxysporum f. sp. cepae

Abstract

The molecular determinants of Foc (Fusarium oxysporum f. sp. cepae) pathogenicity are highly underexplored. The Zn(II)2Cys6 (C6) subclass of zinc finger proteins are an exclusive group of transcriptional regulators associated with multiple physiological processes including development and pathogenicity in fungi. In the present study, we used a genome-wide approach and detected 398C6-type genes (FOXCZF1-398) distributed throughout the Foc genome. The identified proteins were divided into 15 subgroups, majority of which (251, 63%) demonstrated the presence of the highly conserved C6 (CX2CX6CX6CX2CX6C) domain. Phylogenetic analysis clustered the Foc C6-type genes into 12 groups with 45% encoding for fungal specific transcription factors and 17% encoded proteins had a unique developmental specific DUF3468 DNA binding domain. In planta gene expression analysis revealed significant induced expression of a selective group of Foc C6-type genes from group IV and VII. The induced C6-type genes were predicted to be paralogous to the virulence regulatory genes (FTF1 and FTF2) of Fusarium oxysporum. Overall, our study provide a comprehensive information on the genome organization and expression profile of the C6-type gene family in Foc which would form the basis for further analyzing their potential role in regulating pathogenicity to onion by controlling the effector expression in Foc.