RT Journal Article
SR Electronic
T1 Circadian diversity in Swedish <em>Arabidopsis</em> accessions is associated with naturally occurring genetic variation in <em>COR28</em>
JF bioRxiv
FD Cold Spring Harbor Laboratory
SP 665455
DO 10.1101/665455
A1 Hannah Rees
A1 Ryan Joynson
A1 James K.M. Brown
A1 Anthony Hall
YR 2019
UL http://biorxiv.org/content/early/2019/06/10/665455.abstract
AB Circadian clocks have evolved to resonate with external day and night cycles. However, these entrainment signals are not consistent everywhere and vary with latitude, climate and seasonality. This leads to divergent selection for clocks which are locally adapted. To investigate the genetic basis for this, we used a Delayed Fluorescence (DF) imaging assay to screen 191 naturally occurring Swedish Arabidopsis accessions for their circadian phenotypes. We demonstrate period variation with both latitude and sub-population. Several candidate loci linked to period, phase and Relative Amplitude Error (RAE) were revealed by genome-wide association mapping and candidate genes were investigated using TDNA mutants. We show that natural variation in a single non-synonymous substitution within COR28 is associated with a long-period and late-flowering phenotype similar to that seen in TDNA knock-out mutants. COR28 is a known coordinator of flowering time, freezing tolerance and the circadian clock; all of which may form selective pressure gradients across Sweden. Finally, we tested circadian variation under reduced temperatures and show that fast and slow period phenotypic tails remain diverged and follow a distinctive ‘arrow-shaped’ trend indicative of selection for a cold-biased temperature compensation response.