Diurnal rhythms of putative circadian clock genes in Nicotiana attenuata . Expression of orthologs of the circadian clock genes were first examined using our time course microarray data (accession number GSE30287). Wild-type N. attenuata plants were harvested every 4 h for one day from leaves and roots. After RNA isolation, each sample was hybridized on Agilent single color technology arrays designed from the N. attenuata transcriptome (accession number GPL13527). Mean (± SE) levels of transcript abundance of (A) NaLHY, (B) NaTOC1, and (C) NaZTL in leaves (n = 3) and roots (n = 3) at each harvest time. Gray boxes depict the dark period of LD (16 h light/ 8 h dark). Na, Nicotiana attenuata; LHY, late elongated hypocotyl; TOC1, timing of cab expression 1; ZTL, zeitlupe.