Horizontally acquired antibacterial genes associated with adaptive radiation of ladybird beetles

Abstract

Background Horizontal gene transfer (HGT) has been documented in many herbivorous insects, conferring the ability to digest plant material and promoting their remarkable ecological diversification. Previous reports suggest HGT of antibacterial enzymes may have contributed to the insect immune response and limit bacterial growth. Carnivorous insects also display many evolutionary successful lineages, but in contrast to the plant feeders, the potential role of HGTs has been less well-studied. Results Using genomic and transcriptomic data from 38 species of ladybird beetles, we identified a set of bacterial cell wall hydrolase (cwh) genes acquired by this group of beetles. Infection with Bacillus subtilis led to upregulated expression of these ladybird cwh genes, and their recombinantly produced proteins limited bacterial proliferation. Moreover, RNAi-mediated cwh knockdown led to downregulation of other antibacterial genes, indicating a role in antibacterial immune defense. cwh genes are rare in eukaryotes, but have been maintained in all tested Coccinellinae species, suggesting that this putative immune-related HGT event played a role in the evolution of this speciose subfamily of predominant predatory ladybirds. Conclusion Our work demonstrates that, in a manner analogous to HGT-facilitated plant feeding, enhanced immunity through HGT might have played a key role in the prey adaptation and niche expansion that promoted the diversification of carnivorous beetle lineages. We believe that this represents the first example of immune-related HGT in carnivorous insects with an association with a subsequent successful species radiation.

Horizontal Transfer of Microbial Toxin Genes to Gall Midge Genomes

“…The majority of studies on prokaryote-to-insect HGT events have discovered genes involved in conferring new metabolic capabilities, particularly those that allow insects to colonize new plant hosts and adapt to existing ones ( Daimon et al 2008 ; Wybouw et al 2016 ), or toxin-encoding genes involved in antibacterial defenses ( Di Lelio et al 2019 ; Hayes et al 2020 ; Li et al 2021 ). However, our study highlights that HGT of a new functional class of proteins, toxins that antagonize eukaryotic cells, may be more common among insects than previously known.…”

“…HGT facilitates the evolution of novelty in animal immune systems, particularly among arthropods. Antibacterial toxins transferred from bacteria have been described in Ixodes ticks and in several species of Coccinellinae ladybird beetles ( Hayes et al 2020 ; Li et al 2021 ). Some horizontally transferred genes (HTGs) have been co-opted as effectors of the insect immune system.…”

Genomic insight into the scale specialization of the biological control agent Novius pumilus (Weise, 1892)

“…The RNA-Seq data of each species in different life stages and under different treatments (Additional file 3 : Table S3) were mapped using HISAT2 v2.2.0 [ 73 ] and were used to generate a genome-guided assembly by Trinity v2.8.5 [ 74 ] and StringTie v2.1.4 [ 75 ]. Subsequently, PASA v2.4.1 [ 76 ] assembly and prediction were performed with Minimap2, GMAP v2019-03-15 [ 77 ] and BLAT v36x2 [ 78 ] as aligners through the FunAnnotate “train” module, setting the maximum intron length to 20,000 bp, because more than 99.5% of the introns identified in the assembly transcriptome from our previous study are less than 20,000 bp [ 79 ]. Gene models were generated by the consensus of various prediction methods through the FunAnnotate “predict” module.…”

Evolutionary genomics analysis reveals gene expansion and functional diversity of arylalkylamine N‐acetyltransferases in the Culicinae subfamily of mosquitoes

“…HGT can confer powerful adaptive advantages for hosts receiving the transferred gene, including new defensive or detoxification abilities (Li et al. , 2021; Xia et al. , 2021).…”

“…HGT can confer powerful adap-Correspondence: Qian Han, Laboratory of Tropical Veterinary Medicine and Vector Biology, School of Life Sciences, Hainan University, Haikou 570228, China. Email: qianhan@hainanu.edu.cn tive advantages for hosts receiving the transferred gene, including new defensive or detoxification abilities (Li et al, 2021;Xia et al, 2021). Gene duplication, which often takes place after an HGT event, is also generally recognized as an important mechanism of evolutionary processes, providing the raw genetic material for the acquisition of new phenotypes essential for evolution (Dyson & Goodisman, 2020).…”