The evolution and functional divergence of 10 Apolipoprotein D-like genes in Nilaparvata lugens

Abstract

Apolipoprotein D (ApoD), a member of the lipocalin superfamily of proteins, is involved in lipid transport and stress resistance. Whereas only a single copy of the ApoD gene is found in humans and some other vertebrates, there are typically several ApoD-like genes in insects. To date, there have been relatively few studies that have examined the evolution and functional differentiation of ApoD-like genes in insects, particularly hemi-metabolous insects. In this study, we identified 10 ApoD-like genes (NlApoD1−10) with distinct spatiotemporal expression patterns in Nilaparvata lugens (BPH), which is an important pest of rice. NlApoD1−10 were found to be distributed on 3 chromosomes in a tandem array of NlApoD1/2, NlApoD3−5, and NlApoD7/8, and show sequence and gene structural divergence in the coding regions, indicating that multiple gene duplication events occurred during evolution. Phylogenetic analysis revealed that NlApoD1−10 can be clustered into 5 clades, with NlApoD3−5 and NlApoD7/8 potentially evolving exclusively in the Delphacidae family. Functional screening using an RNA interference approach revealed that only NlApoD2 was essential for BPH development and survival, whereas NlApoD4/5 are highly expressed in testes, and might play roles in reproduction. Moreover, stress response analysis revealed that NlApoD3−5/9, NlApoD3−5, and NlApoD9 were up-regulated after treatment with lipopolysaccharide, H₂O₂, and ultraviolet-C, respectively, indicating their potential roles in stress resistance.

Keywords

Apolipoprotein D / BPH / evolution / functional divergence / gene duplication / NlApoD

RIGHTS & PERMISSIONS

2023 Institute of Zoology, Chinese Academy of Sciences.