Transcriptome profiling reveals insights into the molecular mechanism of drought tolerance in sweetpotato

Sweetpotato, Ipomoea batatas (L.) Lam., is a globally important food crop and usually grown on arid-and semi-arid lands. Therefore, investigating the molecular mechanism of drought tolerance will provide important information for the improvement of drought tolerance in this crop. In this study, transcriptome analysis of the drought-tolerant sweetpotato line Xushu 55-2 was conducted on Illumina HiSeq 2500 platform. A total of 86.69 Gb clean data were generated and assembled into 2 671 693 contigs, 222 073 transcripts, and 73 636 unigenes. In total, 11 359 differentially expressed genes (DEGs) were identified after PEG6000 treatment, in which 7 666 were up-regulated and 3 693 were down-regulated. Of the 11 359 DEGs, 10 192 DEGs were annotated in at least one database, and the remaining 1 167 DEGs were unknown. Abscisic acid (ABA), ethylene (ETH), and jasmonic acid (JA) signalling pathways play a major role in drought tolerance of sweetpotato. Drought-inducible transcription factors were identified, some of which have been reported to be associated with drought tolerance and others are unknown in plants. In addition, 7 643 SSRs were detected. This study not only reveals insights into the molecular mechanism of drought tolerance in sweetpotato but also provides the candidate genes involved in drought tolerance of this crop.