Chromosome-level genome assembly of Pterygoplichthys pardalis reveals its genetic basis of extensive invasion

<p>The catfish, <em>Pterygoplichthys</em> <em>pardalis</em>, which belongs to the Loricariidae family, an invasive species which has caused huge damage to the ecological environment. However, the high-quality reference genome for the catfish has not yet been reported. In this study, we successfully assembled the first chromosome-level high-quality genome of <em>P</em>. <em>pardalis</em> using the data we produced from multiple sequencing platforms, which contains 26 chromosomes and with a scaffold N50 of 49.47 Mb. Different evaluation methods all indicate the high connectivity and accuracy of the <em>P</em>. <em>pardalis</em> genome we got. We predicated 23,859 protein-coding genes in the <em>P</em>. <em>pardalis</em> genome, and 22,169 (~92.92%) coding genes could be functionally annotated in public databases. Phylogenetic relationship analysis found <em>P</em>. <em>pardalis</em> was clustered with all the catfishes we used and diverged with them 132.5 million years ago. Besides, whole-genome collinearity analysis found that chromosome 6 of <em>P</em>. <em>pardalis</em> was aligned to two distinct chromosomes both for <em>Ameiurus</em> <em>melas</em>, <em>Pangasianodon</em> <em>hypophthalmus</em> and <em>Ictalurus</em> <em>punctatus</em>, indicating that there may have been a chromosomal fusion/fission event occurred. Furthermore, many immune-system-related genes were large-scale expanded in <em>P</em>. <em>pardalis</em> genome, which may make great contributions to their adaptive traits, even for the highly polluted environmental conditions, and successful invasion. Taken together, this study not only provides insights into the genetic basis of the successful invasion of <em>P</em>. <em>pardalis</em>, but also provides important data resources for comparative genomic analysis of <em>P</em>. <em>pardalis</em> in Siluriformes in the future.</p>