De novo sequencing and comprehensive analysis of the mutant transcriptome from purple sweet potato (Ipomoea batatas L.)

• The special sweet potato mutant (MN1) was studied in this research.
• 7627 unigenes were detected as expressing differently between WTN1 and MN1.
• Eight important genes were verified to be differently expressed between WTN1 and MN1.
• The mutant was predicted to be caused by the mutation of one transcription factor gene.

Purple sweet potatoes, rich in anthocyanin, have been widely favored in light of increasing awareness of health and food safety. In this study, a mutant of purple sweet potato (white peel and flesh) was used to study anthocyanin metabolism by high-throughput RNA sequencing and comparative analysis of the mutant and wild type transcriptomes. A total of 88,509 unigenes ranging from 200 nt to 14,986 nt with an average length of 849 nt were obtained. Unigenes were assigned to Gene Ontology (GO), Clusters of Orthologous Group (COG) and Kyoto Encyclopedia of Genes and Genomes (KEGG). Functional enrichment using GO and KEGG annotations showed that 3828 of the differently expressed genes probably influenced many important biological and metabolic pathways, including anthocyanin biosynthesis. Most importantly, the structural and transcription factor genes that contribute to anthocyanin biosynthesis were downregulated in the mutant. The unigene dataset that was used to discover the anthocyanin candidate genes can serve as a comprehensive resource for molecular research in sweet potato.