Chromosome-level genome assembly and comparative genomics shed light on Helicoverpa assulta ecology and pest management.

ABSTRACT

BACKGROUND: The Oriental tobacco budworm, Helicoverpa assulta, a specialist herbivorous insect that exclusively feeds on plants of the Solanaceae family, causes considerable damage to crops, such as tobacco and hot pepper. The absence of a genome sequence for this species hinders further research on its pest management and ecological adaptation. RESULTS: Here, we present a high-quality chromosome-level genome of a Korean strain of H. assulta (Pyeongchang strain, K18). The total assembly spans 424.4 Mb with an N50 length of 14.54 Mb and 37% GC content. The assembled genome (ASM2961881v1) comprises 31 chromosomes, similar to other congeneric generalist species including H. armigera and H. zea. In terms of genomic assembly quality, the complete BUSCOs and repeat content accounted for 98.3% and 33.01% of the genome, respectively. Based on this assembly, 19 485 protein-coding genes were predicted in the genome annotation. A comparative analysis was conducted using the identified number of protein-coding genes in H. armigera (24154) and H. zea (23696). Out of the 19 485 predicted genes, 137 genes in 15 orthogroups were found to have expanded significantly in H. assulta, while 149 genes in 95 orthogroups contracted rapidly. CONCLUSION: This study revealed specific gene expansions and contractions in H. assulta compared to those in its close relatives, indicating potential adaptations related to its specialized feeding habits. Also, the comparative genome analysis provides valuable insights for the integrated pest management of H. assulta and other globally significant pests in the Heliothinae subfamily. © 2024 Society of Chemical Industry.