Article de revue (Article scientifique dans une revue à comité de lecture)International audienceThis method is derived from the validation studies carried out by ISTA in 2003, in collaborationwith the International Seed Health Initiative for Vegetables (ISHI-Veg) (Sheppard andRemeeus, 2005). For routine testing of bean seed a combination of two complementarysemi-selective media, MT and XCP1, is recommended with a pathogenicity test to confirmsuspect isolates. In 2010 in the USA and France conflicting data were obtained with the new ISTA method.Research in France (GEVES and INRA) and in the Netherlands (Naktuinbouw) showedthat some isolates that were responsible for positive results were causing symptoms in thepathogenicity assay but were not identified as Xap based on molecular methods (geneticbacterial fingerprinting in the Netherlands and pathogen specific PCR’s in France). Thereforeit was concluded that the pathogenicity assay used in the ISTA method, a crucial stepin the Xap test, is not reliable enough.A new pathogenicity assay was developed at INRA to allow a reliable characterizationof the aggressiveness of X. axonopodis pv. phaseoli wild type strains and mutants(Darsonval et al., 2009). A comparison study of the new pathogenicity test and primersspecific for X. axonopodis pv. phaseoli fuscans and non fuscans isolates (Audy et al.,1994;Boureau et al., 2012) was carried out as a collaboration between ISTA, ANSES, INRA andISHI-Veg. This study showed that the new pathogenicity test and Audy et al, (1994) primerswere good confirmation tools and that Diaggene (Boureau et al., 2012) primers gave goodresults but their use did not improve sensitivity of the method.</p
