Rohu: Labeo rohita

Major carp, Rohu (Labeo rohita (Hamilton)), is one of the most important freshwater aquaculture species of South-East Asia and India due to its economic, ecological and cultural attributes. In the Indian subcontinent, a vast majority of the freshwater fishes breed during the monsoon season (June-August) when rainfall is heaviest. Unlike other cyprinid species (for example, common carp and zebrafish) which are prolific breeders independent of season, rohu being seasonal and monsoon dependent does not breed in confined pond water unless induced by hormone. With the recent climate change having frequent irregular and shifted monsoon, propagation of Indian major carps is a much greater challenge. Understanding the reproductive physiology of seasonality at molecular level requires transcriptomic landscaping of tissues involved in BPGL (Brain-Pituitary-Gonad-Liver) axis. Though reproductive genes of rohu are identified but differential gene expression mediating two physiological contrasting phases of reproduction viz., post spawning regression and initiation of gonadal activity is yet to be revealed. Labeo rohita fish transcriptome database is the first genomic resource in the form of candidate genes and regulating pathways along with putative SSR and SNP markers publically available.

This is developed using the de novo assembled transcriptome from ~150 GB Illumina PE reads. It houses 75554 differentially expressed transcripts, 142145 SSRs, 65584 SNPs, 514 pathways, 5379 transcription factors, 187 mature miRNA which regulates candidate genes represented by 1576 differentially expressed transcripts validated using qPCR. This web genomic resource is having ready to use primers for putative markers, developed using PHP and MySQL and freely accessible at http://webtom.cabgrid.res.in/lrtdb/. This resource can be used used as research tool especially in the endeavour of optimizing reproductive efficiency and fish productivity. Further, it can also be of immense use in genome assembly and annotation of rohu.