The Lsm1–7 complex couples 3′-end protection to histone H4 acetylation to maintain mRNA homeostasis in <i>Fusarium graminearum</i>

Eukaryotic messenger RNA (mRNA) homeostasis requires precise coordination between synthesis and decay, yet the mechanisms governing this balance in fungal pathogens remain elusive. Here we provide a comprehensive characterization of the Lsm1-7 complex in the cereal pathogen Fusarium graminearum. We show that Lsm1-7 assembles into a conserved hetero-heptameric module that localizes to processing bodies (P-bodies) and is required for fungal growth, virulence, and mycotoxin biosynthesis. Mechanistically, Lsm1-7/Pat1 binds U/A-rich 3' termini of a defined set of transcripts enriched for central metabolism and restrains their 3'-5' decay. Genetic suppressor analyses and mechanistic dissection identify two parallel decay routes antagonized by Lsm1-7, including the exosome recruited by the uridyltransferase Cid1 and the Ski-exosome complex mediated by the newly identified scaffold protein Lsp1. Moreover, loss of Lsm1-7 elicits a compensatory transcriptional response involving the Rpd3L (Sin3) histone deacetylase complex, in which elevated histone H4 acetylation at affected loci partially restores transcript output. Together, our results define an integrated cytoplasmic-nuclear regulatory axis in F. graminearum that couples 3'-end protection to chromatin-based transcriptional buffering to maintain mRNA homeostasis. While Lsp1 appears lineage-adapted, the underlying logic may reflect a broader principle of gene-expression buffering that supports fungal fitness and pathogenicity.