Effect of small coding genes on the circadian rhythms under elevated CO2 conditions in plants

Increase in atmospheric carbon dioxide (CO 2 ) has a significant effect on plant growth and development. To explore the elevated-CO 2 response, we generated transcriptional profiles over a time course (2 h–14 days) of exposure to elevated CO 2 in Arabidopsis thaliana . Genes related to photosynthesis were down-regulated and circadian rhythm-related genes were abnormally regulated in the early to middle phase of elevated CO 2 exposure. To understand the novel mechanism of elevated CO 2 signaling, we focused on 42 unknown small coding genes that showed differential expression patterns under elevated CO 2 conditions. Four transgenic plants overexpressing the small coding gene exhibited a growth-defective phenotype under elevated CO 2 but not under current CO 2 . Transcriptome analysis showed that circadian rhythm-related genes were commonly regulated in four transgenic plants. These circadian rhythm-related genes were transcribed in the dark when CO 2 concentrations in the leaf was high. Taken together, our identified four small coding genes are likely to participate in elevated CO 2 signaling to the circadian rhythm. Key Message Transcriptome analysis was performed under elevated CO 2 condition in Arabidopsis thaliana . We identified small coding genes associated with signal molecules from elevated CO 2 to circadian rhythm genes.