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Reclassification of Xanthomonads associated with anacardiaceae into two species and three pathovars

Ah-You N., Gagnevin L., Grimont P.A.D., Brisse S., Nesme X., Chiroleu F., Bui Thi Ngoc L., Jouen E., Lefeuvre P., Vernière C., Pruvost O.. 2008. Journal of Plant Pathology, 90 (2) : S2.352. International Congress of Plant Pathology. 9, 2008-08-24/2008-08-29, Turin (Italie).

Mango, cashew, Brazilian pepper and ambarella are host species of Xanthomonas strains which have a broad genetic and phenotypic diversity. Until now, it was not determined whether they should be classified as strains of a single pathovar with a broad host range or as several pathovars. A polyphasic approach was used to determine their respective taxonomie positions, their mutual relationships and their relationship to other Xanthomonas species. Pathogenicity tests and amplified fragment length polymorphism (AFLP) suggested the distinction of three pathovars presenting a host specialization: pv mangiferaeindicae on mango and Brazilian pepper, pv. anacardii on cashew and pv. spondiae on ambarella. AFLP and multilocus sequence analysis (MLSA) were congruent and showed that the three pathovars are related to X. axonopodis genetic groups 9.5, 9.6 and 9.4, respectively. DNADNA hybridization, AFLP and MLSA indicated that pvs. mangiferaeindicae, anacardii and citri (the causal agent of citrus canker) belong to a single species and that they should not be classified as X. axonopodis. Our results agree with the recent elevation of pv citri to, species level and propose to include pvs. mangiferaeindicae and anacardii in this species. Pathovar spondiae is genetically related to group 9.4, for which no reclassification has yet been proposed. (Texte intégral)

Mots-clés : xanthomonas axonopodis; classification; taxonomie; pathotype; anacardiaceae; xanthomonas; xanthomonas axonopodis pv dieffenbachiae; xanthomonas campestris pv. mangiferaeindicae

Thématique : Maladies des plantes

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