Comparative Transcriptome Analysis of Hybrid Population Provides Insights Into Starch Content in Sweet Potato (Ipomoea batatas L.) Storage Root

Sweet potato is an important starchy crop, which is mainly utilized as food, animal feed, and fermented to produce fuel-grade alcohol. However, the genetic mechanism regulating starch content in sweet potato is not yet fully understood. In this study, transcriptome analysis was performed in sweet potato cultivars Luoxushu 8 (high starch), Zhengshu 20 (low starch), and 12 hybrid F1 lines (six high-starch lines and six low-starch lines), which detected a total of 85,493 genes. The high and low-starch content groups were compared and found that 47 and 64 genes were up-regulated and down-regulated, respectively. Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis showed that seven differentially expressed genes were significantly enriched in the ATP-binding cassette (ABC) transporter pathway. Among them, five genes (annotated as ABCB1) that might involve in the auxin transport were significantly down-regulated in high-starch group. Meanwhile, the storage root sizes of Zhengshu 20 were higher as compared with Luoxushu 8. Simultaneously, four of the five differentially expressed genes enriched in the starch and sucrose metabolism pathway were up-regulated in high-starch group. These results provided the basis for the study of starch content in sweet potato storage root.