Transcriptome analysis revealed hub genes for muscle growth in Indian major carp, Catla catla (Hamilton, 1822).

Catla (Catla catla) is the fastest growing Indian major carp species and forms an important component of the freshwater aquaculture systems in the Indian sub-continent. The molecular mechanisms of growth of the species in response to seasonal water temperature variations hitherto are still unknown. In the current study, high-throughput transcriptome sequencing was used to study the differential gene expression pattern in catla muscle tissues between pre-winter and post-winter fingerling groups and fast-growing table size fish. Transcriptome analysis identified 1677 differentially expressed genes (DEGs) in three different growth stages and 236 common DEGs between fingerling at low temperature and table fish post-winter, including four genes under GH/IGF1 axis and 163 genes under signature for compensatory muscle growth. Molecular pathways for the mapped genes identified 42 KEGG pathways and the critical pathways under Environmental Information Processing identified were PI3K-Akt signaling, AMPK signaling pathway, Calcium signaling pathway and MAPK signaling pathway. In this study, 14 differentially expressed potential regulatory hub genes for growth were identified, for the first time and categorized into three major GO groups: unfolded protein binding, rNA processing and biogenesis and muscle development and differentiation. These regulatory hub genes, except acta1, were found to be upregulated in fast-growing table size and post-winter fingerling groups. The results provided valuable information about the key genes, with potential to be used as biomarkers of growth in breeding programs and contributed to our understanding of the molecular mechanisms and pathways regulating muscle growth, in response to temperature fluctuations and different growth stages in C. catla.