The SUMO E3 ligase, AtSIZ1, regulates flowering by controlling a salicylic acid‐mediated floral promotion pathway and through affects on FLC chromatin structure
Open Access
- 30 October 2007
- journal article
- Published by Wiley in The Plant Journal
- Vol. 53 (3), 530-540
- https://doi.org/10.1111/j.1365-313x.2007.03359.x
Abstract
Loss-of-function siz1 mutations caused early flowering under short days. siz1 plants have elevated salicylic acid (SA) levels, which are restored to wild-type levels by expressing nahG, bacterial salicylate hydroxylase. The early flowering of siz1 was suppressed by expressing nahG, indicating that SIZ1 represses the transition to flowering mainly through suppressing SA-dependent floral promotion signaling under short days. Previous results have shown that exogenous SA treatment does not suppress late flowering of autonomous pathway mutants. However, the siz1 mutation accelerated flowering time of an autonomous pathway mutant, luminidependens, by reducing the expression of FLOWERING LOCUS C (FLC), a floral repressor. This result suggests that SIZ1 promotes FLC expression, possibly through an SA-independent pathway. Evidence indicates that SIZ1 is required for the full activation of FLC expression in the late-flowering FRIGIDA background. Interestingly, increased FLC expression and late flowering of an autonomous pathway mutant, flowering locus d (fld), was not suppressed by siz1, suggesting that SIZ1 promotes FLC expression by repressing FLD. Consistent with this, SIZ1 facilitates sumoylation of FLD that can be suppressed by mutations in three predicted sumoylation motifs in FLD (i.e. FLDK3R). Furthermore, expression of FLDK3R in fld protoplasts strongly reduced FLC transcription compared with expression of FLD, and this affect was linked to reduced acetylation of histone 4 in FLC chromatin. Taken together, the results suggest that SIZ1 is a floral repressor that not only represses the SA-dependent pathway, but also promotes FLC expression by repressing FLD activity through sumoylation, which is required for full FLC expression in a FRIGIDA background.Keywords
This publication has 67 references indexed in Scilit:
- NUCLEAR PORE ANCHOR, theArabidopsisHomolog of Tpr/Mlp1/Mlp2/Megator, Is Involved in mRNA Export and SUMO Homeostasis and Affects Diverse Aspects of Plant DevelopmentTHE PLANT CELL ONLINE, 2007
- SIZ1-Mediated Sumoylation of ICE1 ControlsCBF3/DREB1AExpression and Freezing Tolerance inArabidopsisTHE PLANT CELL ONLINE, 2007
- SIZ1 Small Ubiquitin-Like Modifier E3 Ligase Facilitates Basal Thermotolerance in Arabidopsis Independent of Salicylic AcidPlant Physiology, 2006
- Functional Interplay between Histone Demethylase and Deacetylase EnzymesMolecular and Cellular Biology, 2006
- Evolution of a signalling system that incorporates both redundancy and diversity:ArabidopsisSUMOylationBiochemical Journal, 2006
- The Timing of Developmental Transitions in PlantsCell, 2006
- The transcription factor FLC confers a flowering response to vernalization by repressing meristem competence and systemic signaling inArabidopsisGenes & Development, 2006
- Histone Demethylation Mediated by the Nuclear Amine Oxidase Homolog LSD1Cell, 2004
- LHY and CCA1 Are Partially Redundant Genes Required to Maintain Circadian Rhythms in ArabidopsisDevelopmental Cell, 2002
- GIGANTEA: a circadian clock-controlled gene that regulates photoperiodic flowering in Arabidopsis and encodes a protein with several possible membrane-spanning domainsThe EMBO Journal, 1999