The genome of the Hi5 germ cell line from Trichoplusia ni, an agricultural pest and novel model for small RNA biology

Abstract

We report a draft assembly of the genome of Hi5 cells from the lepidopteran insect pest, <i>Trichoplusia ni</i>, assigning 90.6% of bases to one of 28 chromosomes and predicting 14,037 protein-coding genes. Chemoreception and detoxification gene families reveal <i>T. ni</i>-specific gene expansions that may explain its widespread distribution and rapid adaptation to insecticides. Transcriptome and small RNA data from thorax, ovary, testis, and the germline-derived Hi5 cell line show distinct expression profiles for 295 microRNA- and >393 piRNA-producing loci, as well as 39 genes encoding small RNA pathway proteins. Nearly all of the W chromosome is devoted to piRNA production, and <i>T. ni</i> siRNAs are not 2´-<i>O</i>-methylated. To enable use of Hi5 cells as a model system, we have established genome editing and single-cell cloning protocols. The <i>T. ni</i> genome provides insights into pest control and allows Hi5 cells to become a new tool for studying small RNAs ex vivo.