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The surveillance of Xylella fastidiosa in France is implemented with detection methods validated by Anses - Plant Health Laboratory in plants and in Philaenus spumarius. Since 2015, improvements of protocols allowed to detect outbreaks and to identify the subspecies with a good efficiency. Xylella fastidiosa strains detected outdoors in France, identified with official methods, are mainly belonging to the subspecies multiplex (ST6 and ST7). The subspecies pauca (ST53) was only found in one outbreak (Menton on French Riviera).

The validated method (MA039) used in France to detect Xylella fastidiosa in plant samples in the framework of regulated surveillance is based on a Real-Time PCR (Harper et al., 2010) applied on plant DNA extracted with the QuickPick SML kit (Bio-Nobile). The MLST (Multi Locus Sequence Typing) (Yuan et al., 2010, EPPO PM7/24) scheme is applied to identify the sequence types and the subspecies. Until now the bacterium X. fastidiosa subspecies multiplex was mostly detected on about forty plant species, mainly ornamental of the Mediterranean area. These methods were optimized to improve their sensitivity on plant matrices such as olive tree, oak and on the insect vector Philaenus spumarius. They should contribute to the revision of the EPPO protocol.

Since the first outbreak of X. fastidiosa on Polygala myrtifolia (Pm) in natural settings in 2015 in France, the national survey showed that disease is present in many ornamental host plant in environment of Corsica and French Riviera (PACA). X. fastidiosa has been detected on around forty plant species with a validated method based on Real-Time PCR (Harper et al., 2010) associated to DNA extraction with QuickPick™ Plant DNA kit (Bio-Nobile) and KingFisher™ automate (Thermo Fisher Scientific). The sample preparation and isolation performed on modified PWG medium (EPPO, 2016) have been optimized and more than 40 X. fastidiosa strains were isolated from various ornamentals and trees. The characterization of isolates directly on plant or on pure strains is performed according to a multilocus sequence typing (MLST) (http://pubmlst.org/X. fastidiosa/). Following EPPO protocol PM 7/24 isolates were mostly allocated to sequence types ST6 and ST7 (subspecies multiplex). Modifications of the amplification protocol (Yuan et al., 2010) proposed by Denancé et al.(2017) revealed infections linked to the subspecies pauca, sandyi, one recombinant and some mixed infections. EPPO protocol MLST confirmed four isolates in Polygala myrtifolia from PACA contaminated with subsp. pauca but not the identification of other contaminants. These contaminations could not be observed again in the immediate environment after plant eradication. Subspecies assignation directly from plant material is not always successful linked to PCR inhibitors depending of host plants. This study confirms the diversity of subspecies of X. fastidiosa in France. Nevertheless subspecies multiplex was found in the great majority., {"references":["Denance N, Legendre B, Briand M, Olivier V, de Boisseson C, Poliakoff F & Jacques M-A. 2017. Several","Harper SJ, Ward LI, & Clover GRG, 2010. Development of LAMP and Real-Time PCR methods for the","Yuan X., Morano L., Bromley R., Spring-Pearson S., Stouthamer R., & Nunney, L. (2010). Multilocus"]}

The surveillance of Xylella fastidiosa in France is implemented with detection methods validated by Anses - Plant Health Laboratory in plants and in Philaenus spumarius. Since 2015, improvements of protocols allowed to detect outbreaks and to identify the subspecies with a good efficiency. Xylella fastidiosa strains detected outdoors in France, identified with official methods, are mainly belonging to the subspecies multiplex (ST6 and ST7). The subspecies pauca (ST53) was only found in one outbreak (Menton on French Riviera).

The surveillance of Xylella fastidiosa in France is implemented with detection methods validated by Anses - Plant Health Laboratory in plants and in Philaenus spumarius. Since 2015, improvements of protocols allowed to detect outbreaks and to identify the subspecies with a good efficiency. Xylella fastidiosa strains detected outdoors in France, identified with official methods, are mainly belonging to the subspecies multiplex (ST6 and ST7). The subspecies pauca (ST53) was only found in one outbreak (Menton on French Riviera).