Genome of striped eel catfish (Plotosus lineatus) provides insights into the adaptive evolution of amphidromous fish

We sequenced the P. lineatus genome using long-read sequencing technology and combined it with Hi-C technology to obtain high-quality chromosome-level genome data to explore the molecular basis of a series of P. lineatus features, such as a large genome with fewer chromosomes, the novel organ dendritic organ (DO), amphidromous, and venomous nature. Changes in the habitat of P. lineatus may result in genomic enlargement, owing to the wide range of transposon activity caused by genomic shock. The increase in transposon copy number may promote chromosome fusion and translocation. Positive selection and gene family expansion play a role in the adaptive evolution of P. lineatus, particularly in immunity and gametogenesis. Tissue-specific expression analysis revealed that some developmental stages of DO may be similar to those of the kidney, and the existing genes play an important role in the formation of novel organs. We obtained a list of candidate genes related to toxins in P. lineatus and found that these genes may have undergone rapid evolution. Tandem duplication of the stonustoxin gene may be one reason for P. lineatus toxicity. Our findings provide novel insights into the evolution of the genome, chromosomes, adaptation, new organs, and virulence of the striped eel catfish.