Photoperiodism Flashcards

1
Q

How does daylength independent circadian rhythm occur in plants?

A
  • Degredation of miRNA 156 RNA hairpin
  • Leads to cleavage of target genes
  • Targets include SPLs which regulate flower promoting genes
  • miRNA 156 represses flowering in juvenile stage, but decreases with sugar levels
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2
Q

What is the coincidence detector between the plant circadian and daylight timers, what does it regulate?

A
  • Constants (CO)

- regulates abundance of CDF1 which represses transcription of growth factors

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3
Q

How is CO regulated by the circadian rhythm?

A
  • crypto and photochrome react with light causing them to migrate to the nucleus
  • Promoting transcription of CCA1
  • But CCA1 if repressed by TOC1 which is degraded by daylight
  • CCA1 inhibits FKF1
  • FKF1 inhibits CDF1, allowing CO transcription
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4
Q

How is CO regulated by the daylight cycle?

A
  • phyto and cytochromes migrate to nucleus

- CRY and the chromes inhibit COP1, preventing CO degradation

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5
Q

How is CO regulated by the circadian rhythm?

A
  • PR turns to PFR and migrates to nucleus
  • Light also alters CRY which regulates COP1 for export
  • Prevents COP1 from degrading CO, TF for FT
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6
Q

How do the daytime and circadian systems coincide on CO?

A
  • Circadian limits transcription
  • Daylight degrades in absence of long enough light
  • CO promotes FT
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