Effect of H2A.Z deletion is rescued by compensatory mutations in Fusarium graminearum

Abstract

Fusarium head blight is a destructive disease of grains resulting in reduced yields and contamination of grains with mycotoxins worldwide; Fusarium graminearum is its major causal agent. Chromatin structure changes play key roles in regulating mycotoxin biosynthesis in filamentous fungi. Using a split-marker approach in three F. graminearum strains INRA156, INRA349 and INRA812 (PH-1), we knocked out the gene encoding H2A.Z, a ubiquitous histone variant reported to be involved in a diverse range of biological processes in yeast, plants and animals, but rarely studied in filamentous fungi. All ΔH2A.Z mutants exhibit defects in development including radial growth, sporulation, germination and sexual reproduction, but with varying degrees of severity between them. Heterogeneity of osmotic and oxidative stress response as well as mycotoxin production was observed in ΔH2A.Z strains. Adding-back wild-type H2A.Z in INRA349ΔH2A.Z could not rescue the phenotypes. Whole genome sequencing revealed that, although H2A.Z has been removed from the genome and the deletion cassette is inserted at H2A.Z locus only, mutations occur at other loci in each mutant regardless of the genetic background. Genes affected by these mutations encode proteins involved in chromatin remodeling, such as the helicase Swr1p or an essential subunit of the histone deacetylase Rpd3S, and one protein of unknown function. These observations suggest that H2A.Z and the genes affected by such mutations are part or the same genetic interaction network. Our results underline the genetic plasticity of F. graminearum facing detrimental gene perturbation. These findings suggest that intergenic suppressions rescue deleterious phenotypes in ΔH2A.Z strains, and that H2A.Z may be essential in F. graminearum. This assumption is further supported by the fact that H2A.Z deletion failed in another Fusarium spp., i.e., the rice pathogen Fusarium fujikuroi.

Stage-Specific Genetic Interaction between FgYCK1 and FgBNI4 during Vegetative Growth and Conidiation in Fusarium graminearum

“…Like the Fgprp4 , fng1 , and a few other F. graminearum mutants with severe growth defects [ 42 , 56 , 57 , 58 ], the Fgyck1 mutant produced spontaneous suppressors with faster growth rates. By whole genome sequencing of seven selected suppressors, we identified mutations in seven predicted genes, including orthologs of yeast BNI4 , TNA1 , MIG1 , and MSS4 .…”

Ten decadal advances in fungal biology leading towards human well-being

“…H2A.Z has been linked to a wide variety of different sometimes contradictory nuclear functions, including transcriptional activation, transcriptional repression, RNA Polymerase II elongation, heterochromatin, anti-silencing, cell-cycle control, DNA replication, DNA damage repair, chromosome segregation, and genome integrity (Chen and Ponts 2020 ). The function of H2A.Z appears to be essential in a number of organisms, including F. fujikuroi and F. graminearum (Sevilla and Binda 2014 ; Chen et al 2020 ).…”

Effectiveness of the Influence of Selected Essential Oils on the Growth of Parasitic Fusarium Isolated from Wheat Kernels from Central Europe

“…For Fusarium ssp., genetic differentiation of the population structure of races was reported. In particular, the occurrence of specific pathotypes was found [34][35][36][37]. Another paper reported the biological, physiological, and pathogenic differentiation of a genetically homogeneous population of F. oxysporum f.sp.…”

“…The genetic diversity of organisms is significantly increased by mutations. It was found that Fusarium is also subject to mutagenesis [34,35].…”