Impact of host developmental age on the transcriptome of the symbiotic bacterium Buchnera aphidicola in the pea aphid (Acyrthosiphon pisum)

Abstract

Of the 617 genes from Buchnera aphidicola, the obligate bacterial symbiont of the pea aphid, 23% were differentially expressed in embryos compared to adults. Genes involved in flagellar apparatus and riboflavin synthesis exhibited particularly robust upregulation in embryos, suggesting functional differences between the symbiosis in the adult and embryo insect.

FIG. 1.

Differential expression of Buchnera aphidicola genes in pea aphid embryos. Each box represents individual embryo groups (early, intermediate, or late; see text for full definition) or combinations of embryo groups in which B. aphidicola genes were differentially expressed compared to B. aphidicola from the maternal bacteriocytes. Gene names are followed by the log₂ change in expression (n-fold values) and are grouped into upregulated genes (↑), downregulated genes (↓), and those genes expressed in two or more embryo groups with mixed response (MIXED). The values for the change in expression in genes differentially expressed in two or more embryo groups follow the sequence in the group heading. As an example, the sufA gene is differentially expressed in both early and intermediate embryos but is upregulated in early embryos (with a log₂ change of 0.606-fold) and downregulated in intermediate embryos (with a log₂ change of 0.586-fold). The numbers accompanying the arrows in single or mixed groups indicate the number of genes in each category.