Figure 7.

Differential roles for PAR1 and HFR1 during the SAS. A, Number of members of each bHLH subfamily found to interact with PAR1, HFR1, both transcription cofactors, and none of them (N.I.) in Y2H experiments. B, Model for antagonistic transcriptional modules regulating SAS responses. Low R:FR up-regulates the activity of transcription factors like PIFq and PIF7 and the expression of transcription cofactors like PAR1 and HFR1 (in boldface). Repression-activation modules formed by the indicated proteins thus modulate the induction of genes required for elongation growth and the repression of genes involved in carotenoid accumulation (including PSY).