Phytochrome signaling pathway to turn on photomorphogenesis (Arabidopsis thaliana)

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The pathways activated by phytochromes in Arbabidopsis thaliana de-repress transcription regulators important for photomorphogenesis induction by inhibiting COP1, DET1, and CSN directly and indirectly through HMR. The inhibition represses function of Cul4 ubiquitin ligases. However, HMR is also involved in degradation Phytochrome A in the same pathway. Phytochromes further degrade PIFs in another pathway through HMR activation to inhibit repression of photomorphogenesis. Interaction of both pathways has been proposed through inhibition of HFR1 by COP1/DET1 to increase protein stability of PIFs. This pathway is based on figure 3 from Chen et al.