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Histone H 3 K 9 and H 3 K 27 methylation regulates fungal alkaloid biosynthesis in a fungal endophyte–plant symbiosis
Author(s) -
Chujo Tetsuya,
Scott Barry
Publication year - 2014
Publication title -
molecular microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.857
H-Index - 247
eISSN - 1365-2958
pISSN - 0950-382X
DOI - 10.1111/mmi.12567
Subject(s) - biology , methyltransferase , endophyte , histone h3 , gene expression , epigenetics , gene , regulation of gene expression , histone , genetics , methylation , botany
Summary E pichloё festucae is a filamentous fungus that forms a mutually beneficial symbiotic association with L olium perenne. This endophyte synthesizes bioprotective lolitrems ( ltm ) and ergot alkaloids ( eas ) in planta but the mechanisms regulating expression of the corresponding subtelomeric gene clusters are not known. We show here that the status of histone H 3 lysine 9 and lysine 27 trimethylation ( H 3 K 9me3/ H 3 K 27me3) at these alkaloid gene loci are critical determinants of transcriptional activity. Using ChIP ‐ qPCR we found that levels of H 3 K 9me3 and H 3 K 27me3 were reduced at these loci in plant infected tissue compared to axenic culture. Deletion of E . festucae genes encoding the H 3 K 9‐ ( ClrD ) or H 3 K 27‐ ( EzhB ) methyltransferases led to derepression of ltm and eas gene expression under non‐symbiotic culture conditions and a further enhancement of expression in the double deletion mutant. These changes in gene expression were matched by corresponding reductions in H 3 K 9me3 and H 3 K 27me3 marks. Both methyltransferases are also important for the symbiotic interaction between E . festucae and L . perenne . Our results show that the state of H 3 K 9 and H 3 K 27 trimethylation of E . festucae chromatin is an important regulatory layer controlling symbiosis‐specific expression of alkaloid bioprotective metabolites and the ability of this symbiont to form a mutualistic interaction with its host.