Transcriptomic analysis of Litopenaeus vannamei hepatopancreas under cold stress in cold-tolerant and cold-sensitive cultivars

Litopenaeus vannamei (L. vannamei) is one of the most widely cultured shrimp species in the world. The species often suffers from cold stress. To understand the molecular mechanism of cold tolerance, we performed transcriptomic analysis on two contrasting cultivars of L. vannamei, namely, cold-tolerant Guihai 2 (GH2) and cold-sensitive Guihai1 (GH1), under a control temperature (28 degrees C), cold stress (16 degrees C), and recovery to 28 degrees C. A total of 84.5 Gb of sequences were generated from 12 L. vannamei hepatopancreas libraries. The de-novo assembly generated a total of 143,029 unigenes with a mean size of 1,052 bp and an N50 of 2,604 bp, of which 34.08% were annotated in the Nr database. We analyzed the differentially expressed genes (DEGs) between nine comparison groups and detected a total of 21,026 DEGs. KEGG pathways, including lysosome, sphingolipid metabolism and nitrogen metabolism, were significantly enriched by DEGs between different temperatures in GH2. Furthermore, eight of the most significantly DEGs under cold stress from the transcriptomic analysis were selected for quantitative real-time PCR (qPCR) validation. Overall, we compared gene expression changes under cold stress in cold-tolerant and cold-sensitive L. vannamei for the first time. The results may further extend our understanding of the cold stress-response mechanism in L. vannamei.