Mr. Chang Yoon Ji is a graduate student at Korea University of Science and Technology where he is studying environmental biotechnology. He received his BS (2011) from Kyungpook National University, Republic of Korea. His research areas of interests include sweetpotato biotechnology, abiotic stress, and transcriptome analysis.
Sweetpotato [Ipomoea batatas (L.) Lam.] is a globally important root crop with a high industrial value. The optimal storage temperature for sweetpotato is 13-16℃. However, because sweetpotato tuberous roots undergo chilling injuries that negatively affect their quality at temperatures below 10℃, postharvest damage during the winter season is a major constraint for industrialization at the northern hemisphere. So far, the molecular mechanism of postharvest storage at low temperature has not been elucidated in sweetpotato. To elucidate the mechanism of injury 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 1,100 bp. A total of 3,216 differentially expressed genes (DEGs) were detected and categorized into six clusters, of which clusters 2, 4, and 5 (1,464 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 (1,752 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. We are currently focused on RNA-Seq based comparative transcriptomics analyses for both cold-sensitive and –tolerant sweetpotato tuberous roots during low temperature. 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.