Century-old herbarium specimen provides insights into Pierce's disease of grapevines emergence in the Americas

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).

Fossils and other preserved specimens are integral for informing timing and evolutionary history in every biological system. By isolating a plant pathogen genome from herbarium-preserved diseased grapevine material from 1906 (Herb_1906), we were able to answer questions about an enigmatic system. The emergence of Pierce's disease (PD) of grapevine has shaped viticultural production in North America; yet, there are uncertainties about the geographic origin of the pathogen (Xylella fastidiosa subsp. fastidiosa, Xff) and the timing and route of its introduction. We produced a high-quality, de novo genome assembly of this historical plant pathogen and confirmed degradation patterns unique to ancient DNA. Due to the inclusion of the Herb_1906 sample, we were able to generate a significant temporal signal in the genomic data. This allowed us to build a time-calibrated phylogeny, where we estimate the introduction of Xff into the US between 1734 and 1741 CE, an earlier time frame than previously inferred. In a large collection of >300 Xff genomes, the Herb_1906 sample was genetically most similar to a small population from Northern California but not basal to the entire Xff California clade. Based on phylogenetic placement and a phylogeographic reconstruction, our data support a single introduction of Xff into the Southeastern US from Central America, with multiple subsequent introductions into California.

This work was financially supported by Agence Nationale de la Recherche (JCJC MUSEOBACT contract ANR-17-CE35-0009-01), the Thomas Jefferson Fund (TJF19-21), the European Regional Development Fund (ERDF contract GURDT I2016-1731-0006632), the Conseil Régional de La Réunion, the Centre de Coopération Internationale en Recherche Agronomique pour le Développement (CIRAD), the CDFA PD/GWSS Board, and the BeXyl Project (HORIZON ID: 101060593).

Peer reviewed