Fig. 5.

N suppresses the photoperiod pathway by inhibiting circadian transcript oscillation. (A) mRNA abundances of CCA1, TOC1, LHY, CO, GI, and CRY1 in WT plants grown in LN, NN, and HN conditions over a 24-h period. Specific gene expression levels are represented as the percentage relative to ACTIN7 expression level. Error bars show SDs (n = 5). (B) Circadian accumulation of TOC1 mRNA in WT (Col-0), fnr1, and cry1 plants under 3-d continuous light. Samples were collected from seedlings grown in 16-h light/8-h dark for 11 d, and from seedlings that were then transferred to continuous white light for 3 d. (C) Diagram of the putative N-regulated flowering pathway. Phosphorylation of CRY1 triggers its degradation. The CRY1 transcription is feedback-regulated by the circadian clock.