A Phenome-Wide Association Study of the Effects of Fusarium graminearum Transcription Factors on Fusarium Graminearum Virus 1 Infection.

Jisuk Yu,Kook-Hyung Kim

doi:10.3389/fmicb.2021.622261

Abstract

The Fusarium graminearum virus 1 (FgV1) causes noticeable phenotypic changes such as reduced mycelial growth, increase pigmentation, and reduced pathogenicity in its host fungi, Fusarium graminearum. Previous study showed that the numerous F. graminearum genes including regulatory factors were differentially expressed upon FgV1 infection, however, we have limited knowledge on the effect(s) of specific transcription factor (TF) during FgV1 infection in host fungus. Using gene-deletion mutant library of 657 putative TFs in F. graminearum, we transferred FgV1 by hyphal anastomosis to screen transcription factors that might be associated with viral replication or symptom induction. FgV1-infected TF deletion mutants were divided into three groups according to the mycelial growth phenotype compare to the FgV1-infected wild-type strain (WT-VI). The FgV1-infected TF deletion mutants in Group 1 exhibited slow or weak mycelial growth compare to that of WT-VI on complete medium at 5 dpi. In contrast, Group 3 consists of virus-infected TF deletion mutants showing faster mycelial growth and mild symptom compared to that of WT-VI. The hyphal growth of FgV1-infected TF deletion mutants in Group 2 was not significantly different from that of WT-VI. We speculated that differences of mycelial growth among the FgV1-infected TF deletion mutant groups might be related with the level of FgV1 RNA accumulations in infected host fungi. By conducting real-time quantitative reverse transcription polymerase chain reaction, we observed close association between FgV1 RNA accumulation and phenotypic differences of FgV1-infected TF deletion mutants in each group, i.e., increased and decreased dsRNA accumulation in Group 1 and Group 3, respectively. Taken together, our analysis provides an opportunity to identify host’s regulator(s) of FgV1-triggered signaling and antiviral responses and helps to understand complex regulatory networks between FgV1 and F. graminearum interaction.

Highlights

Virus divert many cellular resources to produce virus-specific components and counteract to host defense responses during virus infection (Carrera and Elena, 2012)
Members of TF families belonging to WRKY family, myeloblastosis related proteins (MYB), basic leucine zipper, APETELA2/Ethylene-Responsive Factor (AP2/ERF) family, and NAC transcription factors have been shown to be associated with defense response against plant viruses as well as abiotic stress responses (Alves et al, 2014; Ng et al, 2018)
Previous study identified 16 putative TFs involved in DNA damage responses (DDRs) (Son et al, 2016a). We found that these DDR TF gene deletion group included relatively high portion of Fusarium graminearum virus 1 (FgV1)-infected TF deletion mutants that belong to Groups 1 and 3

Summary

Introduction

Virus divert many cellular resources to produce virus-specific components and counteract to host defense responses during virus infection (Carrera and Elena, 2012). Systematic loss-of function studies and transcriptomic studies under comparable condition provide new insights into the role of TFs in complex regulatory networks for mycotoxin biosynthesis, sexual development, and virulence in F. graminearum (Son et al, 2011; Kim et al, 2015; Kazan and Gardiner, 2018; Chen Y. et al, 2019; Guo et al, 2020). Their interconnection and specific roles on signaling pathways, are largely unknown. Each of TF deletion mutant was categorized by phenotypic characteristics, such as mycelial growth, sexual and asexual developments, virulence, toxin production, and stress responses (Son et al, 2011)

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