Transcriptome responses to elevated CO₂ level and Wolbachia-infection stress in Hylyphantes graminicola (Araneae:...

Hylyphantes graminicola is a resident spider species found in maize and cotton fields and is an important biological control agent of various pests. Previous studies have demonstrated that stress from elevated CO₂ and Wolbachia infection can strongly affect spider species. Thus, based on CO₂ levels (400 ppm, current atmospheric CO₂ concentration and 800 ppm, high CO₂ concentration) and Wolbachia status (Wolbachia-infected, W⁺ and Wolbachia-uninfected, W^- ), we divided H. graminicola individuals into four treatment groups: W^- 400 ppm, W^- 800 ppm, W⁺ 400 ppm, and W⁺ 800 ppm. To investigate the effects of elevated CO₂ levels (W^- 400 vs W^- 800), Wolbachia infection (W^- 400 vs W⁺ 400), and the interactions between these two factors (W^- 400 vs W⁺ 800), high-throughput transcriptome sequencing was employed to characterize the de novo transcriptome of the spiders and identify stress-related differentially expressed genes (DEGs). De novo assembly of complementary DNA sequences generated 86 688 unigenes, 23 938 of which were annotated in public databases. A total of 84, 21, and 157 DEGs were found among W^- 400 vs W^- 800, W^- 400 vs W⁺ 400, and W^- 400 vs W⁺ 800, respectively. Functional enrichment analysis revealed that metabolic processes, signaling, and catalytic activity were significantly affected by elevated CO₂ levels and Wolbachia infection. Our findings suggest that the impact of elevated CO₂ levels and Wolbachia infection on the H. graminicola transcriptome was, to a large extent, on genes involved in metabolic processes. This study is the first description of transcriptome changes in response to elevated CO₂ levels and Wolbachia infection in spiders.