Mutant screening
T-DNA and EMS mutants were obtained from the NottinghamArabidopsis Stock centre (RRID:SCR_004576) and primers designed using the iSect tool from the SIGnAL website. In addition, seed forcor28-2, cor27-1 and cor28-2/cor27-1 was kindly donated from Hongtao Liu’s laboratory (Shanghai, China) where these mutants have previously been identified as long-period using leaf-movement and ProCCR2:LUC constructs (X. Li et al., 2016). Cor28-2 is a null mutant and cor28-1, cor27-1 and cor27-2 are all knockdown mutants. Gene candidates, mutant IDs and primers used can be viewed in Supplementary File 2. All lines were genotyped to confirm homozygosity by PCR and gel electrophoresis prior to seed bulking other thansco2 which was genotyped by sanger sequencing to reveal the premature stop. We were unable to obtain or confirm homozygous mutants for dnf and fab1c and therefore these lines were not DF screened (Supplementary File 2). SALK lines for elf3 were not obtained as the elf3-1 mutant has been previously confirmed in Box et al. 2015 as having a phenotype of reduced robustness using delayed fluorescence imaging (Box et al., 2015). WT control lines; Col-0 and Ler were grown for seed in parallel to standardize seed quality. Forcor28-1 , a homozygous WT control was derived by segregation of the original heterozygous TDNA line was used as a control. Five imaging experiments using a single camera and cabinet were carried out with each line present in at least three experiments. We did not apply a mixed model to the mutant screening data because only one camera was used.