Identification and Analysis of SUX4, a suppressor of axe1
Date Issued
2010
Date
2010
Author(s)
Lin, Shun-Chiang
Abstract
The floral transition is major developmental switch in the plant life cycle, which is regulated by both environmental and endogenous cues. HDA6 is a RPD3-type histone deacetylase (HDAC) in Arabidopsis thaliana. The Arabidopsis HDA6 mutant, axe1-5, showed a late-flowering phenotype, in which FLC was up-regulated. By screening plants derived from EMS mutagenized axe1-5 seeds, we isolated an early-flowering mutant, suppressor of axe1 (sux4). sux4axe1-5 plants flowered early in both long day (LD) and short day (SD). By backcrossing sux4axe1-5 with Col, sux4 mutant was isolated. sux4 also displayed early flowering in both LD and SD. In sux4 plants, FLC expression was not changed but SOC1and FT expression was increased, suggesting that SUX4 regulate flowering by affecting SOC1and FT expression, independently of FLC. In ChIP assay, histone H3 hyperacetylation is deposited on FLC chromatin in axe1-5, but sux4 mutation does not affect H3 acetylation caused by axe1-5, suggesting that SUX4 acting downstream of HDA6 to regulate flowering.
We also analyzed the siz1-3 mutant, which has an early-flowering phenotype similar to that of the sux4axe1-5 plant. AtSIZ1 is a SUMO E3 ligase which conjugates small ubiquitin modifier peptides to a target protein. It has been demonstrated that SIZ1-mediated SUMO modification of FLD represses H4 deacetylation of FLC chromatin. In this study, we found that SIZ1 interacts with HDA6/HDA19 by BiFC assay. These results suggest that SIZ1 might mediate sumoylation on HDA6/HDA19 to affect histone acetylation on FLC chromatin.
Subjects
flowering transition
histone modification
sumoylation
Type
thesis
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