MYB96 recruits the HDA15 protein to suppress negative regulators of ABA signaling in Arabidopsis

Hong Gil Lee,Pil Joon Seo

doi:10.1038/s41467-019-09417-1

Hong Gil Lee, Pil Joon Seo

Open Access

https://doi.org/10.1038/s41467-019-09417-1

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Journal: Nature Communications	Publication Date: Apr 12, 2019
Citations: 80	License type: open-access

Affiliation: Seoul National University

Abstract

Unlike activation of target genes in response to abscisic acid (ABA), how MYB96 transcription factor represses ABA-repressible genes to further enhance ABA responses remains unknown. Here, we show MYB96 interacts with the histone modifier HDA15 to suppress negative regulators of early ABA signaling. The MYB96-HDA15 complex co-binds to the promoters of a subset of RHO GTPASE OF PLANTS (ROP) genes, ROP6, ROP10, and ROP11, and represses their expression by removing acetyl groups of histone H3 and H4 from the cognate regions, particularly in the presence of ABA. In support, HDA15-deficient mutants display reduced ABA sensitivity and are susceptible to drought stress with derepression of the ROP genes, as observed in the myb96-1 mutant. Biochemical and genetic analyses show that MYB96 and HDA15 are interdependent in the regulation of ROP suppression. Thus, MYB96 confers maximal ABA sensitivity by regulating both positive and negative regulators of ABA signaling through distinctive molecular mechanisms.

Highlights

Unlike activation of target genes in response to abscisic acid (ABA), how MYB96 transcription factor represses ABA-repressible genes to further enhance ABA responses remains unknown
MYB96 is a pivotal regulator of ABA signaling and mediates a variety of physiological responses required for environmental stress adaptation in plants[10,11,12,13,14,30,31]
The MYB96 protein fused with the GAL4 activation domain (AD) was coexpressed in yeast cells with the full-length HDA15 protein fused with the GAL4 DNA binding domain (BD)

Summary

Introduction

Unlike activation of target genes in response to abscisic acid (ABA), how MYB96 transcription factor represses ABA-repressible genes to further enhance ABA responses remains unknown. We show MYB96 interacts with the histone modifier HDA15 to suppress negative regulators of early ABA signaling. ABSCISIC ACID RECEPTOR (PYR/PYL/RCAR) family proteins[3,4] These receptors constitute early ABA signaling modules, together with PROTEIN PHOSPHATASE 2Cs (PP2Cs) and subfamily 2 SNF1-RELATED PROTEIN KINASEs (SnRK2s)[5,6]. The ABA-inducible MYB96 transcription factor binds to the promoters of many ABA-responsive genes and usually activates expression to optimize plant growth and fitness under unfavorable conditions[10,11,12]. Like many plant transcription factors[16], MYB96 has been suspected to bind to the promoters of ABA-repressed genes, such as negative regulators of ABA signaling, and sometimes functions as a transcriptional repressor to further enhance plant responses to environmental stresses[17,18,19]

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