A Plant Bacterial Pathogen Manipulates Its Insect Vector's Energy Metabolism

Insect-transmitted plant-pathogenic bacteria may alter their vectors' fitness, survival, behavior, and metabolism. Because these pathogens interact with their vectors on the cellular and organismal levels, potential changes at the biochemical level might occur. " Liberibacter asiaticus" ( Las) is transmitted in a persistent, circulative, and propagative manner. The genome of Las revealed the presence of an ATP translocase that mediates the uptake of ATP and other nucleotides from medium to achieve its biological processes, such as growth and multiplication. Here, we showed that the levels of ATP and many other nucleotides were significantly higher in Las-infected than healthy psyllids. Gene expression analysis showed upregulation for ATP synthase subunits, while ATPase enzyme activity showed a decrease in ATPase activity. These results indicated that Las stimulated to produce more ATP and many other energetic nucleotides, while it may inhibit their consumption by the insect. As a result of ATP accumulation, the adenylated energy charge (AEC) increased and the AMP/ATP and ADP/ATP ratios decreased in Las-infected psyllids. Survival analysis confirmed a shorter life span for Las-infected psyllids. In addition, electropenetrography showed a significant reduction in total nonprobing time, salivation time, and time from the last E2 (phloem ingestion) to the end of recording, indicating that Las-infected psyllids were at a higher hunger level and they tended to forage more often. This increased feeding activity reflects the Las-induced energetic stress. In conclusion, Las alters the energy metabolism of its psyllid vector, , in order to secure its need for energetic nucleotides. Insect transmission of plant-pathogenic bacteria involves propagation and circulation of the bacteria within their vectors. The transmission process is complex and requires specific interactions at the molecular and biochemical levels. The growth of the plant-pathogenic bacteria in the hemolymph of their vectors indicated that the hemolymph contains all the necessary nutrients for their growth. In addition to nutrients, " Liberibacter asiaticus" ( Las) can take up energetic nucleotides, such as ATP, from its vector, , using ATP translocase. In this study, we found that the Las pathogen manipulates the energy metabolism of its insect vector. The accumulation of ATP in Las-infected psyllids indicated that Las induces ATP production to fulfill its need for this energetic compound. As a resul