Histone acetyltransferase HAF2 associates with pyruvate dehydrogenase complex to control H3K14ac and H3K23ac in ethylene response

Ethylene plays essential roles in plant development, growth, and defense responses by controlling transcriptional reprogramming, in which ETHYLENE INSENSITIVE 2-C-terminal end (EIN2-C)-directed regulation of histone acetylation is the first key step for chromatin to perceive ethylene signaling. However, the histone acetyltransferase (HAT) in this process remains unknown. Here, we identify HAF2 as the missing HAT, as HAF2 mutations confer ethylene hyposensitivity. HAF2 interacts with EIN2-C in response to ethylene, and its bromodomain preferentially binds H3K14ac, while its HAT domain acetylates H3K14 and H3K23, favoring H3K14. Chromatin immunoprecipitation sequencing confirms HAF2's role in regulating H3K14ac and H3K23ac. Additionally, HAF2 cooperates with the pyruvate dehydrogenase complex (PDC) to modulate histone acetylation in an EIN2-dependent manner. Our findings establish HAF2 as the key HAT that, together with EIN2-C and PDC, orchestrates H3K14ac and H3K23ac deposition, preferentially targeting H3K14, in response to ethylene.