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A new type of strain of Xanthomonas euvesicatoria causing bacterial spot of tomato and pepper in Grenada

Hamza A.A., Robène-Soustrade I., Boyer C., Laurent A., Jouen E., Wicker E., Prior P., Pruvost O.. 2010. Plant Disease, 94 (10) : p. 1264-1264.

Bacterial spot of tomato and pepper (BSTP) can be caused by several Xanthomonas genospecies. BSTP is a major disease in Grenada where A and B phenotypic groups (Xanthomonas euvesicatoria and X. vesicatoria, respectively, [2]) have been reported. There is no previous report of group A strains, which are strongly amylolytic and pectolytic, in Grenada. In March 2007, tomato and pepper leaves with lesions typical of BSTP were collected in Saint David and Saint Andrew parishes of Grenada. Bacterial isolations were performed on KC semiselective agar medium (4), resulting in isolation of five yellow-pigmented, Xanthomonas-like strains. Three strains isolated from tomato or pepper in Saint David were negative for starch hydrolysis and pectate degradation, two tests that were found useful for strain identification in the 1990s (2). Two strains isolated from pepper in Saint David were strongly amylolytic and degraded pectate. Amplified fragment length polymorphism (AFLP) and multilocus sequence analysis (MLSA) assays targeting atpD, dnaK, efp, and gyrB were performed on the five strains from Grenada together with a type strain of each of X. euvesicatoria, X. perforans, X. gardneri, and X. vesicatoria as well as other reference strains of X. euvesicatoria and X. perforans as described previously. All strains from Grenada were identified as X. euvesicatoria regardless of the typing technique. On the basis of AFLP assays, the two strains with phenotypic features not reported in Grenada were closely related (distances of ?0.002 nucleotide substitutions per site [1]) to a group of strains from India (ICMP 3381, LMG 907, LMG 908, and LMG 918). These two strains were also identical to the Indian strains based on MLSA, but differed from the X. euvesicatoria type strain by at least one nucleotide substitution in all loci examined. The three strains from Grenada that were negative for starch hydrolysis and pectate degradation had sequences identical to that of t

Mots-clés : xanthomonas; lycopersicon esculentum; capsicum annuum; réunion; xanthomonas euvesicatoria

Thématique : Maladies des plantes

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