Transcriptome analysis and metabolic profiling of green and red kale (Brassica oleracea var. acephala) seedlings

•The 49,471 transcripts were identified in kale transcriptome datasets.•Sixty-eight secondary metabolite biosynthetic genes were identified in transcriptome.•Forty-three secondary metabolites were detected in green and red kale seedlings.•Some secondary metabolites were positively correlated with its biosynthetic genes.•Most secondary metabolites were higher in red kale than in green kale. Kale (Brassica oleracea var. acephala) is a rich source of numerous health-benefiting compounds, including vitamins, glucosinolates, phenolic compounds, and carotenoids. However, the genetic resources for exploiting the phyto-nutritional traits of kales are limited. To acquire precise information on secondary metabolites in kales, we performed a comprehensive analysis of the transcriptome and metabolome of green and red kale seedlings. Kale transcriptome datasets revealed 37,149 annotated genes and several secondary metabolite biosynthetic genes. HPLC analysis revealed 14 glucosinolates, 20 anthocyanins, 3 phenylpropanoids, and 6 carotenoids in the kale seedlings that were examined. Red kale contained more glucosinolates, anthocyanins, and phenylpropanoids than green kale, whereas the carotenoid contents were much higher in green kale than in red kale. Ultimately, our data will be a valuable resource for future research on kale bio-engineering and will provide basic information to define gene-to-metabolite networks in kale.