Epigenetic silencing of a multifunctional plant stress regulator EIN2 (eLIFE)

EIN2 is a key regulator of the ethylene response and a protein with a complex function and regulation. Zander et al. have uncovered an interesting and complex mechanism by which its expression is regulated. Many genes are regulated through histone modifications, with the histone variant H2A.Z and the histone mark H3K27me3 both repressors of transcription. The ein6-1 mutant is a fast-neutron generated mutant that the authors have now shown carries mutations in two different unlinked genes. The ethylene hyposensitive phenotype occurs in what the authors refer to as the ein6-1 single mutant; this gene encodes a histone methyltransferase. The second mutation is in a gene they have named EIN6 ENHANCER (EEN), which alone has no phenotype but which enhances the ein6-1 phenotype. They show that in wild-type plants, these two gene products work cooperatively to remove repressive chromatin marks, and when both are mutated the EIN2 gene is not expressed. They conclude, “These results uncover a unique type of chromatin regulation which safeguards the expression of an essential multifunctional plant stress regulator.” (Summary by Mary Williams) eLIFE 10.7554/eLife.47835