Fig. 7: The circadian clock morning loop is overexpressed in the late day under shade conditions.

a, Using gene homology to Arabidopsis, we extracted the clock genes embedded in cycles of activation and repression, with the morning loop promoting photosynthesis and the evening loop promoting respiration. The regulatory relationships of circadian clock components are represented in a network with connecting lines ending in arrows indicating activation and those ending in T’s indicating repression. The up and down arrows indicate differential expression, with each arrow indicating a gene copy and its direction corresponding to up- or downregulation. The loss of TOC1 in Zostera is represented as a greying out of those regulatory connections. Gene information, including K_a/K_s values and log fold changes, are presented in Supplementary Table 5. b, Observations made in this late-afternoon sampling procedure support a theory that adaptive Zostera circadian clock regulation shifts periodicity under low-light conditions.