701 / 2019-05-01 21:41:34

SHORT VEGETATIVE PHASE negatively regulates PHYTOCHROME-INTERACTING FACTOR 4 expression

PIF4,SVP,Flowering

Growth and Development > Growth and Development

Perception of temperature change play a key role in plant growth. PHYTOCHROME INTERACTING FACTOR4 (PIF4), transcription factor that directly interacts with photo receptor PHYTOCHROME and regulates the hypocotyl elongation, has been known to respond to elevated temperatures. Publicly available ChIP-seq results, suggested that SHORT VEGETATIVE PHASE (SVP) protein binds to the PIF4 exonic regions led us to hypothesize that SVP acts as a regulator of PIF4 expression in plant development.
First we measured the PIF4 expression level in SVP overexpressing plant and svp-32 mutants. The PIF4 transcripts were abundant in svp-32, whereas the PIF4 expression levels were decreased in SVP over-expressing plants. We also investigated that SVP function is associated with hypocotyl elongation. The svp-32 mutants exhibited more elongated hypocotyls compared with SVP-overexpressing plant, which was consistent with the result of PIF4 expression. To test whether SVP directly interacts with the PIF4 sequence, we conducted EMSA assays, which showed that SVP protein directly binds to the CArG motif presented in the PIF4. The band-shift were found in CArG motif 1 and CArG motif 3and severe decreases in band shifts with their mutant forms were observed, suggesting that SVP protein regulates PIF4 expression through association to the CArG regions. Our results suggest that PIF4 expression is negatively regulated by SVP protein. A-role of SVP as a negative regulator of PIF4 will be further discussed.