The liver transcriptome of suckermouth armoured catfish (Pterygoplichthys anisitsi, Loricariidae): Identification of expansions in defensome gene families

•Resistance of P. anisitsi to organic pollutants (e.g. Diesel oil) is elevated.•> 60 thousand transcripts were assembled at high sequencing depth.•> 20 thousand transcripts were annotated using UniProt and GO databases.•Complete coding sequence for 183 defensome transcripts were identified.•Most abundant defensome families were P450 followed by SULT, NR and ABC transporters.

Pterygoplichthys is a genus of related suckermouth armoured catfishes native to South America, which have invaded tropical and subtropical regions worldwide. Physiological features, including an augmented resistance to organic xenobiotics, may have aided their settlement in foreign habitats. The liver transcriptome of Pterygoplichthys anisitsi was sequenced and used to characterize the diversity of mRNAs potentially involved in the responses to natural and anthropogenic chemicals. In total, 66,642 transcripts were assembled. Among the identified defensome genes, cytochromes P450 (CYP) were the most abundant, followed by sulfotransferases (SULT), nuclear receptors (NR) and ATP binding cassette transporters (ABC). A novel expansion in the CYP2Y subfamily was identified, as well as an independent expansion of the CYP2AAs. Two expansions were also observed among SULT1. Thirty-two transcripts were classified into twelve subfamilies of NR, while 21 encoded ABC transporters. The diversity of defensome transcripts sequenced herein could contribute to this species' resistance to organic xenobiotics.