Comparative transcriptomics of aphid species that diverged > 22 MYA reveals genes that are important for the maintenance of their symbiosis

Abstract

Most plant-sap feeding insects have obligate relationships with maternally transmitted bacteria. Aphids require their nutritional endosymbiont, Buchnera aphidicola, for the production of essential amino acids. Such endosymbionts are harbored inside of specialized insect cells called bacteriocytes. Here, we use comparative transcriptomics of bacteriocytes between two recently diverged aphid species, Myzus persicae and Acyrthosiphon pisum, to identify key genes that are important for the maintenance of their nutritional mutualism. The majority of genes with conserved expression profiles in M. persicae and A. pisum are for orthologs previously identified in A. pisum to be important for the symbiosis. However, asparaginase which produces aspartate from asparagine was significantly up-regulated only in A. pisum bacteriocytes, potentially because Buchnera of M. persicae encodes its own asparaginase enzyme unlike Buchnera of A. pisum resulting in Buchnera of A. pisum to be dependent on its aphid host for aspartate. One-to-one orthologs that explained the most amount of variation for bacteriocyte specific mRNA expression for both species includes a collaborative gene for methionine biosynthesis, multiple transporters, a horizontally transmitted gene, and secreted proteins. Finally, we highlight species-specific gene clusters which may contribute to host adaptations and/or accommodations in gene regulation to changes in the symbiont or the symbiosis.

Unveiling metabolic integration in psyllids and their nutritional endosymbionts through comparative transcriptomics analysis

“…To further explore the similarities and differences in gene expression between D. citri and B. cockerelli, we conducted Principal Component Analyses (PCA) on the relative expression of one-to-one orthologs similar to Argandona et al. (2023), 32 Georgiadou et al. (2022) 33 and Korb et al.…”

“…(2022) 33 and Argandona et al. (2023), 32 one-to-one orthologs were further examined for inter-species gene expression comparisons. Specifically, the relative magnitude of changes of orthologs in bacteriomes were compared to body tissues for each species using Principal Components Analyses (PCA).…”

“…Following the same RNAseq pipeline detailed in Pers & Hansen (2021) 58 and Argandona et al. (2023), 32 raw RNA-seq reads were quality checked and trimmed with FASTQC v.0.11.8 81 and Trimmomatic v. 0. 36 82 with the following parameters: ILLUMINACLIP:TruSeq3-PE.fa:2:30:10 LEADING:3 TRAILING:3 SLIDINGWINDOW:4:15 MINLEN:36.…”

“…(2023). 32 In this context, “logFC” indicate log2 fold change between the groups and “logFC” ≥ 0.5849 represents significantly up-regulated genes and “logFC” ≤ −0.5849 represents significantly down-regulated genes. Gene Set Enrichment Analysis (GSEA, v4.…”

‘Drifting’Buchneragenomes track the microevolutionary trajectories of their aphid hosts

“…We know very little about segregating patterns of Buchnera variation within and among different clonal lineages of M. persicae . Some prior work has suggested that the Buchnera of M. persicae exhibit a greater retention of genes important for nutritional symbioses (e.g., aspartate, methionine, and queosine production) relative to other aphid species, which may be linked to the polyphagous nature of their M. persicae host (Argandona, Kim, & Hansen, 2023; Douglas, 1988; Jiang et al, 2013). Prior global analysis of M. persicae clones revealed an association between the aphid host genome and different plant host families (Singh et al, 2021).…”