The HAC1 Histone Acetyltransferase Promotes Leaf Senescence via Regulation of ERF022

Abstract

1Nutrient remobilization during leaf senescence nourishes the growing plant. Understanding the 2 regulation of this process is essential for reducing our dependence on nitrogen fertilizers and increasing 3 agricultural sustainability. Our lab is interested in chromatin changes that accompany the transition to 4 leaf senescence. Previously, darker green leaves were reported for Arabidopsis thaliana hac1 mutants, 5 defective in a gene encoding a histone acetyltransferase in the CREB-binding protein family. Here, we 6show that two Arabidopsis hac1 alleles display delayed age-related developmental senescence, but have 7 normal dark-induced senescence. Using a combination of ChIP-seq for H3K9ac and RNA-seq for gene 8 expression, we identified 44 potential HAC1 targets during age-related developmental senescence. 9Genetic analysis demonstrated that one of these potential targets, ERF022, is a positive regulator of leaf 10 senescence. ERF022 is regulated additively by HAC1 and MED25, suggesting MED25 recruits HAC1 to the 11 ERF022 promoter to increase its expression in older leaves. 12

WHIRLY1 recruits the histone deacetylase HDA15 repressing leaf senescence and flowering in Arabidopsis

“…Because of the early flowering phenotype of the hda15 and why1hda15 mutants, we further compared the DEGs in the hda15 or why1hda15 mutants (fold change >1.5, FDR <0.05) to 389 bolting‐associated genes (BAGs) from a previously published dataset (Hinckley et al, 2019). This showed that the expression of 77 or 87 BAGs was significantly up‐regulated whereas 93 or 102 down‐regulated in hda15 or why1hda15 , respectively (Figure S8A, B).…”

“…In Arabidopsis , histone acetyltransferase 1 ( hac1 ) mutants display delayed age‐related developmental senescence. Moreover, hac1 increased the levels of H3K9ac and H3K4me3 and the expression of ERF022 , which is a positive regulator of leaf senescence (Hinckley et al, 2019). Furthermore, HDA9 and HOS15 form a complex with PWR and WRKY53 to repress the expression of the negative regulators during senescence (Chen et al, 2016; Zareen et al, 2022).…”

“…The involvement of histone acetylation and deacetylation in leaf senescence have also been reported. The histone acetyltransferase HAC1 promotes leaf senescence and flowering (Hinckley et al, 2019). HISTONE DEACETYLASE 9 (HDA9) forms a complex with POWERDRESS and WRKY53, and WRKY53 directs POWERDRESS and HDA9 to the W‐box containing promoters of several negative senescence regulators including AUTOPHAGY 9 ( ATG9 ), NUCLEAR PROTEIN X 1 ( NPX1 ), and WRKY57 to promote leaf senescence (Chen et al, 2016).…”