Xylella fastidiosa is reported in over 563 plant species from 82 botanical families worldwide, but we cannot consider it a simply ‘generalist’ bacterium. Its capacity to successfully colonize and cause disease in naïve hosts varies with subspecies and populations. Each of them has a unique evolutionary story as being subjected to diverse ecological forces. Knowing more about those interactions and their role in the evolutionary mechanisms leading to host adaptation in specific environments can benefit the management of possible outbreaks in naïve territories. Plus, this kind of research can bring new light on the understanding of the evolution of X. fastidiosa as a worldwide pathogen.
The XF-Actors researchers used whole genome sequences to relate the development of the two subspecies of Xylella fastidiosa present in Costa Rica (subsp. fastidiosa and pauca) to ecological and evolutionary factors. In addition, they compared the sequences with those of other populations from other parts of the world.
The results support the hypothesis that the subsp. fastidiosa is native to Central America, that is the source population for outbreaks in North America and the putative introduction point of subsp. pauca from South America. Also, results suggest that the combination of adaptive (positive selection to a monoculture) and non-adaptive (the so-called founder effect) evolutionary forces might be key to understand the X. fastidiosa host-switching and host adaptation mechanisms.
Read/download via BMC Genomics: https://doi.org/10.1186/s12864-020-06778-6