Demonstration of transcriptional regulation of specific genes by phytochrome action

We have developed an in vitro transcription system that uses nuclei isolated from Lemna gibba G-3

J. Silverthorne

2006

Scholarcy highlights

  • We have developed an in vitro transcription system that uses nuclei isolated from Lemna gibba G-3
  • Phytochrome is known to be involved in the regulation of expression of small subunit, light-harvesting chlorophyll a/b-protein, and several other nucleus-encoded chloroplast proteins at the level of translatable mRNA
  • In the case of the NADPH-protochlorophyllide reductase and phytochrome itself, phytochrome action is involved in the dark induction of mRNA
  • The present study shows that transcripts labeled in vitro in isolated Lemna nuclei have the same relative amounts of SSU and LHCP sequences after the different light treatments as they do of these translatable and hybridizable mRNAs
  • Since a larger proportion of the total radioactivity incorporated after red light treatment is due to rRNA synthesis and because equal amounts of radioactivity are used in each hybridization, our estimates of the relative phytochrome-induced increases in the transcription of SSU and LHCP sequences are minimal values
  • If this is the case, the apparent magnitude of the response to red light would be reduced, and it would suggest that the transcription of SSU and LHCP genes is differentially sensitive to red light
  • The latter explanation seems more likely, since 10 min of far-red light alone results in some stimulation of transcription of pLg52 sequences and light-harvesting chlorophyll a/b-protein and small subunit sequences

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