Functional Analysis Of Histone Acetyltransferases (HATs) And Ubiquitination-related Gene FgUbx5 In Fusarium Graminearum

Fusarium heading blight caused by Fusarium graminearum is a devastating disease in wheat production.Due to the global warming and the promotion of rice-wheat rotation and no-tillage technology,the frequency of epidemic outbreaks of wheat scab in China has increased year by year,causing serious production and economic losses.In addition to this,the residual mycotoxins produced by F.graminearum cause food contamination in cereals,which seriously threatens the health of people and livestock.Therefore,understanding the molecular mechanism of F.graminearum growth and development and pathogenicity is an important prerequisite for effective control of the pathogen.Epigenetic modification of protein acetylation and ubiquitination plays an important role in the interaction between host plants and pathogenic bacteria.In this paper,four histone acetyltransferase(HATs)genes and one ubiquitination-related protein gene Fg Ubx5 were identified from the F.graminearum genome,and we studied the basic phenotypic traits and their effect on transcriptome and protein levels for revealing their mechanism of functions in the growth,development and pathogenesis of F.graminearum.(A)Effect of Fusarium graminearum histone acetyltransferase on growth and histone acetylation1.Effects of four HATs genes on the growth and development.Four HATs genes,Fg GCN5,Fg RTT109,Fg SAS2 and Fg SAS3,were searched from the genome database.Fg GCN5 and Fg SAS3 have significant effects on the mycelial growth rate,stress response,conidial yield,sexual reproduction,virulence and DON production of F.graminearum;Fg RTT109 has a significant effect on conidial yield,sexual reproduction,pathogenicity;Fg SAS2 significantly affects the production of conidia.2.Analysis of histone acetylation catalyzed by Fg GCN5 and Fg SAS3.In the ?FgGCN5 mutant,the acetylation levels of H3 ac,H3K9ac,H3K14 ac,H3K18ac,and H3K27 ac were significantly reduced.The acetylation levels of H3K4 and H3K14 in ?Fg SAS3 mutant were significantly reduced.These results indicate that Fg GCN5 is responsible for the lysine acetylation at positions 9,14,18 and 27 of histone H3,whereas Fg SAS3 specifically catalyzes the acetylation at the H3K4 and H3K14 sites,and the complete acetylation of H3K14 is only available under the combined action of Fg SAS3 and Fg GCN5.(B)Study on metabolic regulation of HAT gene Fg GCN5 and Fg SAS3 in F.graminearum.Transcriptome sequencing analysis revealed 3375 and 2438 differentially expressed genes in ?FgSAS3 and ?Fg GCN5,respectively.Fg GCN5 affects a variety of biological processes including ribosome biosynthesis,r RNA processing,nc RNA processing and cellular amino acid metabolism,whereas the Fg SAS3 mainly affects redox,transmembrane transport,and carbon metabolism.In these differential expressed genes,the expression levels of multiple transcription factors,sexual development related genes,virulence related genes,and secondary metabolic genes were significantly down-regulated.F.graminearum.(C)Effects of UBX domain-containing gene Fg Ubx5 on the growth and development ofThe growth rate of ?Fg Ubx5 mutants slowed down,colonies showed irregular morphology,spore production decreased,and sexual reproductive capacity was lost,indicating that deletion of the Fg Ubx5 gene affected the growth and development of F.graminearum.The DON productivity of ?Fg Ubx5 mutants decreased,and they could not penetrate cellophane.The amount of active oxygen accumulation increased and the pathogenic ability decreased significantly.In a variety of stress-stress experiments,the sensitivity of ?Fg Ubx5 mutants to various stress agents was reduced.(D)Study on metabolic regulation of UBX domain-containing gene Fg Ubx5Transcriptomic analysis showed that there were a total of 2664 differentially expressed genes in ?Fg Ubx5.GO enrichment analysis showed that Fg Ubx5 mainly involved in the maturation of r RNA and the transmembrane transport of ions and amino acids.The total protein ubiquitination level increased under nitrogen starvation conditions,indicating that Fg Ubx5 is involved in protein ubiquitination and degradation.Affinity capture mass spectrometry analysis selected a total of 71 candidate proteins interacting with Fg Ubx5.Co-immunoprecipitation experiments further validated the interaction between Fg Ubx5 and Cdc48.In summary,histone acetyltransferase and Fg Ubx5 gene play a crucial role in the growth,development,environmental stress and pathogenicity of F.graminearum.This provides a theoretical basis for the analysis of the growth and development and elucidation of mycotoxins synthesis and pathogenic mechanism of F.graminearum.