Transcriptomic variations associated with salinity stress in Penaeus indicus.

BACKGROUND

The Indian white shrimp, Penaeus indicus a native species of India, is important brackishwater aquaculture species. Shrimps are euryhaline in nature and they regulate osmotic and ionic concentrations by osmoregulatory process. However, variations in abiotic factors such as salinity result in stress to the shrimps during culture period affecting their growth and immunity.

METHODS AND RESULTS

To understand the adaptive mechanism to stress in low salinity conditions, RNA-seq was used to compare the transcriptomic response of P. indicus upto 3 weeks. De novo assembly using Trinity assembler generated a total of 173,582 transcripts. The assembly had a mean length of 854 bp, N50 value of 1243 bp and GC content of 42.33%. Differential gene expression analysis, resulted in identification of 2130, 3090, and 5351 DEGs in 7 days, 14 days and 21 days respectively of salinity stress period. The pathway prediction of the assembled trinity transcripts using KEGG database showed total number of 329 pathways linking 12,430 transcripts. KEGG pathway enrichment analyses led to the identification of several enriched pathways related to lipid metabolism, amino acid metabolism, glycolysis, signalling pathways etc. Selected genes involved in osmoregulatory process and immune response in shrimps were validated and analysed for the gene expression levels by quantitative real-time PCR (qPCR).

CONCLUSION

This study on the adaptive transcriptomic response of P. indicus to low salinity, will further help in our understanding of the molecular mechanisms underlying osmoregulation mechanism in shrimps.