Research articleTranscriptome profiling of sweetpotato tuberous roots during low temperature storage

- Transcriptome of sweetpotato tuberous roots during low temperature storage was de novo assembled and analyzed.
- A total of 3,216 differentially expressed genes (DEGs) were identified in sweetpotato tuberous roots stored at 13 °C and 4 °C.
- Genes involved in lipid metabolism were differentially expressed under low temperature.
- Genes involved in pathogen defense, and phenylalanine metabolism were generally up-regulated at low temperature.
- Genes involved in antioxidant enzyme, carbohydrate, or energy metabolism were generally down-regulated at low temperature.

Sweetpotato [Ipomoea batatas (L.) Lam] is a globally important root crop with high industrial value. However, because sweetpotato tuberous roots undergo chilling injuries that negatively affect their quality at temperatures below 10 °C, postharvest damage during the winter season is a major constraint for industrialization. To understand chilling injury response during postharvest low temperature storage, we used next-generation sequencing technology to comprehensive analyze the transcriptome of tuberous roots stored at optimal (13 °C) or low temperature (4 °C) for 6 weeks. From nine cDNA libraries, we produced 298,765,564 clean reads, which were de novo assembled into 58,392 unigenes with an average length of 1100 bp. A total of 3216 differentially expressed genes (DEGs) were detected and categorized into six clusters, of which clusters 2, 4, and 5 (1464 DEGs) were up-regulated under low temperature. The genes in these three clusters are involved in biosynthesis of unsaturated fatty acids, pathogen defense, and phenylalanine metabolism. By contrast, genes in clusters 1, 3, and 6 (1752 DEGs), which were generally down-regulated at low temperature, encode antioxidant enzymes or are involved in glycerophospholipid, carbohydrate, or energy metabolism. We confirmed the results of the transcriptome analysis by quantitative RT-PCR. Our transcriptome analysis will advance our understanding of the comprehensive mechanisms of chilling injury during low temperature storage and facilitate improvements in postharvest storage of sweetpotato tuberous roots.