Clock controlled and cold induced CDF6 alters growth and development to changing temperatures

The circadian clock represents a critical regulatory network, which allows plants to anticipate environmental changes as inputs and promote plant survival by regulating various physiological outputs. Here, we examine the function of the clock-regulated transcription factor, CYCLING DOF FACTOR 6 (CDF6), during cold stress in Arabidopsis thaliana. We found that the clock gates CDF6 transcript accumulation in the vasculature during cold stress. CDF6 mis-expression results in an altered flowering phenotype during both ambient and cold stress. A genome-wide transcriptome analysis links CDF6 to genes associated with flowering and seed germination during cold and ambient temperatures, respectively. Analysis of key floral regulators indicates that CDF6 alters flowering during cold stress by repressing photoperiodic flowering components, FLOWERING LOCUS T (FT), CONSTANS (CO), and BROTHER OF FT (BFT). Gene ontology enrichment further suggests that CDF6 regulates circadian and developmental associated genes. These results provide insight into how the clock-controlled CDF6 modulates plant development during moderate cold stress. Overall design: Measured transciptome changes in Columbia-0 (WT), cdf6, and SUC2::CDF6 under ambient (22°C) and 1-hr cold (10°C) temperature on 11-day-old seedlings entrained in diurnal light for 8 days before transfer to constant light for two days. Three replicates were sampled for all genotypes and conditions at ZT0.