Symbiopectobacterium purcellii strain:MEX Genome sequencing
It is difficult to observe the initiation of dependent animal-bacterial symbioses in nature, as well as the early impact of this process on interacting genomes. We recently identified a leafhopper-associated symbiont with flexible ecological capabilities that can shed light on these processes. Using long-read genomic sequencing technology, we assembled a complete genome for this host-associated bacterial symbiont (Symbiopectobacterium purcellii MEX; S-MEX). In turn, we identified the hallmarks of a transitioning symbiotic relationship, including the expansion of insertion elements and the unique loss of genes involved in free-living lifestyles. These features are key theoretical predictions for the establishment of highly dependent animal-microbe symbiosis, driven by population reduction, reduced selection, and metabolic streamlining. Taken together, this genome provides a potential snapshot of the key transition towards animal host dependence from a plant pathogenic state.