A chromosome-level genome assembly of Neotoxoptera formosana (Takahashi, 1921) (Hemiptera: Aphididae).

Abstract

Neotoxoptera formosana (Takahashi), the onion aphid, is an oligophagous pest that mainly feeds on plants from the Allium genus. It sucks nutrients from the plants and indirectly acts as a vector for plant viruses. This aphid causes severe economic losses to Allium tuberosum agriculture in China. To better understand the host plant specificity of N. formosana on Allium plants and provide essential information for the control of this pest, we generated the entire genome using Pacific Biosciences long-read sequencing and Hi-C data. Six chromosomes were assembled to give a final size of 372.470 Mb, with an N50 scaffold of 66.911 Mb. The final draft genome assembly, from 192 Gb of raw data, was approximately 371.791 Mb in size, with an N50 contig of 24.99 Kb and an N50 scaffold of 2.637 Mb. The average GC content was 30.96%. We identified 73 Mb (31.22%) of repetitive sequences, 14,175 protein-coding genes, and 719 noncoding RNAs. The phylogenetic analysis showed that N. formosana and Pentalonia nigronervosa are sister groups. We found significantly expanded gene families that were involved in the THAP domain, the DDE superfamily endonuclease, zinc finger, immunity (ankyrin repeats), digestive enzyme (serine carboxypeptidase) and chemosensory receptor. This genome assembly could provide a solid foundation for future studies on the host specificity of N. formosana and pesticide-resistant aphid management.