A pathogen of good taste: genetics of a bacterial host jump of the plant pathogen Xylella fastidiosa from coffee to wine grapes

Beyond Xylella, Integrated Management Strategies for Mitigating Xylella fastidiosa Impact in Europe (BeXyl) (Grant Agreement 101060593). Partner/Coordinador principal: Blanca B. Landa del Castillo, Investigadora Científica del Instituto de Agricultura Sostenible (IAS-CSIC).

When pathogens are repeatedly introduced into new environments, host jumps may occur into naïve taxa. Given the magnitude of the global plant trade, this process can lead to frequent disease emergence as interactions between previously isolated pathogens and new plant hosts become possible. Xylella fastidiosa is a recurring nuisance. This bacterial pathogen has recently emerged in novel geographic locations infecting a breadth of host plants. An introduction of X. fastidiosa subsp. fastidiosa from Central America to the USA several hundred years ago has since been the source of outbreaks across the globe. In the USA, particularly in California, the introduced bacterium is frequently found in European grapevine (Vitis vinifera). In this study, we demonstrated that the introduced strains do not persistently infect Coffea arabica. Furthermore, we did not observe an overall increase in the virulence of the introduced strains towards coffee, indicating a lack of hypervirulence. Then, using X. fastidiosa subsp. fastidiosa whole-genome sequences, 15 from the source region of Costa Rica and 289 from the introduced clade, we tested for traces of adaptation to grapevines. We found both genes and SNPs that are associated with the host shift to grapevines. These results support the hypothesis that a host jump with genetic adaptation occurred following the introduction of the pathogen into the USA.

We would like to thank the CDFA PD/GWSS Board and the BeXyl Project (HORIZON, ID: 101060593) for funding this work.

Peer reviewed