Starch content differences between two sweet potato accessions are associated with specific changes in gene expression.

Sweet potato (Ipomoea batatas (L.) Lam.) is one of the most important root crops in the world. Initial formation and development of storage roots (SRs) are key factors affecting its yields. In order to study the molecular mechanism and regulatory networks of the SRs development process, we have analyzed root transcriptomes between the high and low starch content sweet potato accessions at three different developmental stages. In this study, we assembled 46,840 unigenes using Illumina paired-end sequencing reads and identified differentially expressed genes (DEGs) between two accessions. The numbers of DEGs were increased with the development of SRs, indicating that the difference between two accessions is enlarging with the maturation. DEGs were mainly enriched in starch biosynthesis, plant hormones regulatory, and genetic information processing pathways. Then, expression patterns of DEGs that are most significant and starch biosynthesis related were validated using qRT-PCR. Our results provide valuable resources to future study on molecular mechanisms of SRs development and candidate genes for starch content improvement in sweet potato.