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

Psyllids, a group of insects that feed on plant sap, have a symbiotic relationship with an endosymbiont called . synthesizes essential amino acids and vitamins for its psyllid host, but lacks certain genes required for this process, suggesting a compensatory role of psyllid host genes. To investigate this, gene expression was compared between two psyllid species, and , in specialized cells where resides (bacteriomes). Collaborative psyllid genes, including horizontally transferred genes, showed patterns of conserved gene expression; however, species-specific patterns were also observed, suggesting differences in the nutritional metabolism between psyllid species. Also, the recycling of nitrogen in bacteriomes may primarily rely on glutamate dehydrogenase (). Additionally, lineage-specific gene clusters were differentially expressed in and bacteriomes and are highlighted here. These findings shed light on potential host adaptations for the regulation of this symbiosis due to host, microbiome, and environmental differences.