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First report in Ghana of Xanthomonas citri pv. mangiferaeindicae causing mango bacterial canker on Mangifera indica

Pruvost O., Boyer C., Vital K., Gagnevin L., De Bruno Austin L., Rey J.Y.. 2011. Plant Disease, 95 (6) : p. 774-774.

DOI: 10.1094/PDIS-02-11-0098

Bacterial canker of mango (or bacterial black spot), caused by Xanthomonas citri pv. mangiferaeindicae, is an economically important disease in tropical and subtropical producing areas (1). X. citri pv. mangiferaeindicae can cause severe infection in a wide range of mango cultivars and induces raised, angular, black leaf lesions, sometimes with a chlorotic halo. Several months after infection, leaf lesions dry and turn light brown or ash gray. Severe leaf infection may result in abscission. Fruit symptoms appear as small water-soaked spots on the lenticels. These spots later become star shaped, erumpent, and exude an infectious gum. Often, a "tear stain" infection pattern is observed on the fruit. Severe fruit infections will cause premature fruit drop. Twig cankers are potential sources of inoculum and weaken resistance of branches to wind damage. Leaf lesions with suspected bacterial canker were collected in January 2010 from mango trees cv. Keitt in several blocks at the Integrated Tamale Fruit Company, Ghana. Non-pigmented Xanthomonas-like bacterial colonies were isolated on Kasugamycin-Cephalexin semiselective agar medium (3). On the basis of IS1595-Ligation Mediated-PCR data, 16 strains from Ghana produced identical fingerprints and were identified as X. citri pv. mangiferaeindicae (4). The haplotype corresponding to the Ghanaian strains had not been previously reported. On the basis of multidimensional scaling (4), this haplotype clustered together with a group of strains from multiple origins and the analysis was not informative as an aid for tracing back the outbreak. Five Ghanaian strains (LH2-3, LH2-6, LH2-8, LH2-11, and LH2-15) were compared by multilocus sequence analysis to the type strain of X. citri and the pathotype strain of several X. citri pathovars, including pvs. anacardii and mangiferaeindicae. This assay targeted the atpD, dnaK, efp, and gyrB genes as described previously (2). Nucleotide sequences were 100% identical to those of the pathotype

Mots-clés : mangifera indica; xanthomonas campestris citri; étiologie; ghana; afrique occidentale; burkina faso; xanthomonas citri pv mangiferaeindicae; Émergence

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