Validation by quantitative on-line RT-PCR analyses of the differential expression between sweetpotato initiating storage and fibrous roots revealed by the use of Illumina-based sequencing at the cDNA level. Expression levels were measured in initiating storage root (ISR) and fibrous root (FR) samples of Georgia Jet sweetpotato variety, using at least four biological replicates. Each replicate consisted of cDNA representing pooled root tissue from 30 plants. Quantitative RT-PCR was performed and values were normalized relative to the expression levels of 18S rRNA in the same cDNA sample. Expression data are the means (± SE) of at least four replicates and are presented as relative expression values of the respective gene in the ISR sample relative to its expression in the FR sample (ISR/FR). The Y axis has a logarithmic scale. ADP glucose pyrophosphorylase – AGPase; coumaroyl-CoA synthase – 4CL; caffeoyl-CoA O-methyltransferase – CCoAOMT; cinnamyl alcohol dehydrogenase – CAD.