(A) Normalized bioluminescence activity of CCA1:LUC in spy-3, prr5–1, spy-3 prr5–1 and Col-0 plants in red light. Data represent mean ± SE (n = 15).
(B) Scatter plot showing that the lengthened circadian period phenotype of spy-3 could be partially rescued by prr5–1, the null mutation of PRR5.
(C) The estimated circadian period of spy-3, prr5–1, spy-3 prr5–1 and Col-0 plants. Data represent mean ± SE (n = 15 seedlings). ***p < 0.001 (Student t-test).
(D) Normalized bioluminescence activity of CCA1:LUC in spy-3, 35S:PRR5-GFP, 35S:PRR5-GFP spy-3 and Col-0 plants in continuous monochromatic red light. Data represent mean ± SE (n > 10).
(E) Scatter plot showing that the lengthened circadian period phenotype of 35S:PRR5-GFP is not increased by SPY mutation.
(F) The estimated circadian period of spy-3, 35S:PRR5-GFP, 35S:PRR5-GFP spy-3 and Col-0 plants. Data represent mean ± SE (n > 10). ***p < 0.001 (Student’s t-test).
(G) A proposed model of the molecular mechanism by which SPY fine-tunes circadian period in Arabidopsis. SPY fine-tunes circadian speed in nucleus, where it physically interacts with PRR5 and affects PRR5 protein stability.