Abstract
PHYTOCHROME INTERACTING FACTOR3 (PIF3) is a key basic helix-loop-helix transcription factor of Arabidopsis thaliana that negatively regulates light responses, repressing chlorophyll biosynthesis, photosynthesis, and photomorphogenesis in the dark. However, the mechanism for the PIF3-mediated transcription regulation remains largely unknown. In this study, we found that the REDUCED POTASSIUM DEPENDENCY3/HISTONE DEACETYLASE1-type histone deacetylase HDA15 directly interacted with PIF3 in vivo and in vitro. Genome-wide transcriptome analysis revealed that HDA15 acts mainly as a transcriptional repressor and negatively regulates chlorophyll biosynthesis and photosynthesis gene expression in etiolated seedlings. HDA15 and PIF3 cotarget to the genes involved in chlorophyll biosynthesis and photosynthesis in the dark and repress gene expression by decreasing the acetylation levels and RNA Polymerase II-associated transcription. The binding of HDA15 to the target genes depends on the presence of PIF3. In addition, PIF3 and HDA15 are dissociated from the target genes upon exposure to red light. Taken together, our results indicate that PIF3 associates with HDA15 to repress chlorophyll biosynthetic and photosynthetic genes in etiolated seedlings.
Highlights
Light is one of the most important environmental factors that govern plant growth and development
It was reported that PHYTOCHROME INTERACTING FACTOR3 (PIF3) may act as a negative regulator in the gene expression involved in chlorophyll biosynthesis and photosynthesis (Shin et al, 2009; Stephenson et al, 2009)
HDA15 and PIF3 fused with the C terminus (YC) or the N terminus (YN) of yellow fluorescent protein (YFP) were cotransformed into protoplasts and incubated in the dark (D) or 10 μmol m22 s21 red light (RL) for 12 h. mCherry was used as a nuclear maker
Summary
Light is one of the most important environmental factors that govern plant growth and development. Plants can detect almost all facets of light, such as direction, duration, quantity, and wavelength using three major classes of photoreceptors: phytochromes (PHY), cryptochromes, and phototropins (Fankhauser and Chory, 1997). In Arabidopsis thaliana, red/far-red (R/FR) light receptors, phytochromes (PHYA to PHYE), regulate various light responses by initiating the transcriptional cascades that alter the expression of 10 to 30% of the entire transcriptome (Ma et al, 2001; Tepperman et al, 2001; Jiao et al, 2005). Light-regulated gene expression has served as a paradigm to understand transcriptional regulatory mechanisms in plants (Bertrand et al, 2005). A number of light-responsive transcription factors have been
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