Comparative transcriptome analysis of purple-fleshed sweet potato provides insights into the molecular mechanism of anthocyanin biosynthesis

Hongyuan Zhao ,Shanshan Zhang ,Feibing Wang ,Jian Xu ,Shaozhen He ,Qingchang Liu ,Hong Lin Zhai

doi:10.15302/j-fase-2018219

Abstract

Sweet potato, <i>Ipomoea batatas</i>, is a globally important food crop. The purple-fleshed sweet potato, rich in anthocyanins, has great potential for both nutritional and pharmaceutical uses. In this study, we characterized the root transcriptomes of the purple-fleshed sweet potato cv. Jingshu 6 and its mutant JS6-5 with high anthocyanin content by high-throughput RNA sequencing. A total of 22873364 and 27955097 high quality reads were obtained from Jingshu 6 and JS6-5, respectively, and assembled into 35592 unigenes. In all, we obtained 1566 differentially expressed genes (DEGs). Among them, 994 were upregulated and 572 were downregulated in JS6-5 compared to the expression in Jingshu 6. A total of 1436 DEGs were annotated, in which 847 DEGs had gene ontology (GO) terms and 329 DEGs were assigned to 84 Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways. Most importantly, 23 differentially expressed genes and 24 transcription factors were identified as candidate genes involved in anthocyanin biosynthesis. In addition, 2349 SSRs were detected. This study not only provides the candidate genes but also provides insights into the molecular mechanism of anthocyanin biosynthesis in sweet potato.

Highlights

Sweet potato, Ipomoea batatas, a globally important food crop, has high yielding potential and wide adaptability
Transcription factors of the MYB, basic helix–loop–helix and WD40 classes can form a MBW complex which binds to promoters and induces transcription of the phenylpropanoid[8] and anthocyanin[9] biosynthetic pathway genes, including those encoding phenylalanine ammonia lyase (PAL), cinnamate 4-hydroxylase (C4H), 4-coumarate CoA
The sequences of 35592 assembled unigenes were searched in the Nr, Swiss-Prot, protein family (Pfam), KOG, gene ontology (GO), Cluster of Orthologous Groups (COG) and Kyoto Encyclopedia of Genes and Genomes (KEGG) databases

Summary

Introduction

Ipomoea batatas, a globally important food crop, has high yielding potential and wide adaptability. CHS, CHI, F3H, F3′H, F3′5′H, DFR, ANS/LDOX and UFGT are key enzymes controlling the metabolism of flavonoids, of which DFR, Hongyuan ZHAO et al Comparative transcriptome analysis of purple-fleshed sweet potato. Several anthocyanins biosynthesisassociated genes including IbCHI, IbF3′H, IbDFR, IbANS, IbMYB1, IbWD40 and IbMADs10 have been isolated from purple-fleshed sweet potato[11,12,13,14,15,16,17]. Their overexpression or downregulation was found to significantly affect anthocyanin levels. The anthocyanin biosynthetic pathway is well characterized, the molecular mechanisms regulating flux through the pathway are still unclear

Methods

Results

Conclusion