Microbial associations between insects and their host plants often involve plant pathogens that cause diseases. Candidatus Liberibacter taxon is a prominent microbe responsible for plant diseases in economically important plant species. However, the role of Ca. Liberibacter as a facultative endosymbiont in psyllid-microbiome interactions remains poorly understood. Here, we investigate the tissue-specific gene expression patterns in the symbiotic organs of the potato/tomato psyllid, Bactericera cockerelli (Psylloidea: Triozidae) to understand metabolic impact of Ca. Liberibacter psyllaurous (also known as Ca. L. solanacearum) on its psyllid host. Using transcriptomic approach, we found over 10% of all B. cockerelli genes are significantly differentially expressed in Ca. L. psyllaurous infected bacteriome or body tissues compared to the uninfected ones. These differentially expressed genes include those that are related to the nutritional symbiosis with the obligate endosymbiont of B. cockerelli, Ca. Carsonella ruddii. By analyzing previously generated data, we also observed differential expression patterns in Ca. L. psyllaurous-uninfected B. cockerelli feeding on tomato plants compared to those feeding on pepper plants. Notably, the majority of symbiosys-related genes are significantly up-regulated in the uninfected bacteriome from B. cockrelli feeding on tomato plants compared to those feeding on pepper plants, while minimal changes occur between the infected and the uninfected body tissues. These findings enhance our understanding of the interactions between Ca. Liberibacter and its psyllid host, shedding light on the metabolic dynamics within psyllid microbiomes.
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