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In the original publication [1], the information contained in Table 1 concerning the Sequence Type (ST) and host of some of the Xylella fastidiosa strains was not correct. Xylella fastidiosa subsp. multiplex strains RH1 and LM10 belong to ST 7 instead of ST 6. Xylella fastidiosa subspecies multiplex Fillmore belongs to ST 81 instead of ST 6. Regarding to Xylella fastidiosa, subsp. multiplex ST 6 IVIA6586-2 was isolated from Helicrysum italicum, and IVIA6629 was isolated from Rhamnus alaternus instead of Prunus dulcis, as it is said in the original table. This mistake does not affect the results or information provided in the main body of the manuscript.

Xylella fastidiosa (Xf) is a phytopathogenic bacterium with a repertoire of self-replicating genetic elements, including plasmids, pathogenicity islands, and prophages. These elements provide potential avenues for horizontal gene transfer both within and between species and have the ability to confer new virulence traits, including the ability to colonize new host plants. However, they can also serve as a 'footprint' to type plasmid-bearing strains. Genome sequencing of several strains of Xf subsp. fastidiosa sequence type (ST) 1 from Mallorca Island, Spain, revealed the presence of a 38 kb plasmid (pXFAS_5235). In this study, we developed a PCR-based typing approach using primers targeting the traC gene to determine the presence of pXFAS_5235 plasmid or other plasmids carrying this gene in a world-wide collection of 65 strains X. fastidiosa from different subspecies and STs or in 226 plant samples naturally infected by the bacterium obtained from the different outbreaks of Xf in Spain. The traC gene was amplified only in the plant samples obtained from Mallorca Island infected by Xf subsp. fastidiosa ST1 and from all Spanish strains belonging to this ST. Maximum-likelihood phylogenetic tree of traC revealed a close relatedness among Spanish and Californian strains carrying similar plasmids. Our results confirm previous studies, which suggested that a single introduction event of Xf subsp. fastidiosa ST1 occurred in the Balearic Islands. Further studies on the presence and role of plasmids in Xf strains belonging to the same or different subspecies and STs can provide important information in studies of epidemiology, ecology, and evolution of this plant pathogen.