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Arabidopsis SUMO E3 Ligase SIZ1 Interacts with HDA6 and Negatively Regulates HDA6 Function during Flowering.

ABSTRACT: The changes in histone acetylation mediated by histone deacetylases (HDAC) play a crucial role in plant development and response to environmental changes. Mammalian HDACs are regulated by post-translational modifications (PTM), such as phosphorylation, acetylation, ubiquitination and small ubiquitin-like modifier (SUMO) modification (SUMOylation), which affect enzymatic activity and transcriptional repression. Whether PTMs of plant HDACs alter their functions are largely unknown. In this study, we demonstrated that the Arabidopsis SUMO E3 ligase SAP AND MIZ1 DOMAIN-CONTAINING LIGASE1 (SIZ1) interacts with HISTONE DEACETYLASE 6 (HDA6) both in vitro and in vivo. Biochemical analyses indicated that HDA6 is not modified by SUMO1. Overexpression of HDA6 in siz1-3 background results in a decreased level of histone H3 acetylation, indicating that the activity of HDA6 is increased in siz1-3 plants. Chromatin immunoprecipitation (ChIP) assays showed that SIZ1 represses HDA6 binding to its target genes FLOWERING LOCUS C (FLC) and MADS AFFECTING FLOWERING 4 (MAF4), resulting in the upregulation of FLC and MAF4 by increasing the level of histone H3 acetylation. Together, these findings indicate that the Arabidopsis SUMO E3 ligase SIZ1 interacts with HDA6 and negatively regulates HDA6 function.

SUBMITTER: Gao S

PROVIDER: S-EPMC8616286 | biostudies-literature |

REPOSITORIES: biostudies-literature

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The Arabidopsis SUMO E3 ligase SIZ1 mediates the temperature dependent trade-off between plant immunity and growth

Project description:Increased ambient temperature is widely considered to be inhibitory to basal and effector-triggered plant immunity. For example, SNC1-dependent auto-immunity in Arabidopsis results in enhanced basal resistance at 22ºC, which is fully suppressed at 28ºC. The sumoylation mutant siz1 also displays auto-immunity at 22ºC. We find that its auto-immunity is sustained at 28ºC while still requiring PAD4/EDS1 and SNC1 function. Moreover, its rosette size does not fully recover at 28ºC, which is normally seen for SNC1 gain-of-function mutants. Related, thermomorphogenesis is also compromised in the SUMO mutants. This role of SIZ1 in growth regulation does not depend on PAD4 or SNC1. In corroboration, SUMO mutants show a global delay in their transcriptional profile for thermosensitive growth regulators and these differentially expressed genes show an overrepresentation for PIF4 genomic targets. This transcription factor (TF) PIF4 is the central regulator of thermomorphogenesis, while also inhibiting plant immunity at 28ºC. Our findings thus reveal that SUMO conjugation has a central role in PIF4 regulation prioritizing growth over immunity at elevated temperatures. Such molecular understanding of how temperature affects growth over immunity is important to mitigate the effects of climate change on agriculture This experiment we have examined how gene expression is affected in two SUMO mutants (siz1-2; sumo1 amiR-SUMO1 [aka. sumo1/2KD] ) when the plants are placed at 28C constant ambient temperature, which is a condition normally used to induce thermomorphogenesis. We used as control the pad1-4 background, as the siz1-2 and sumo1/2KD mutants normailly suffer from constitutive defence signalling due hyperaccumulation of SA, which is suppressed by introgression of pad4 in these backgrounds.

2018-01-02 | GSE97641 | GEO

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