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First report of Xanthomonas citripv. mangiferaeindicae causing mango bacterial canker on Mangifera indica L. in Benin

Zombré C., Sankara P., Ouédraogo S., Wonni I., Pruvost O., Boyer C., Vernière C., Adandonon A., Vayssières J.F., Ahohuendo B.C.. 2015. Plant Disease, 99 (12) : p. 1854.

Bacterial canker (or bacterial black spot) caused by Xanthomonas citri pv. mangiferaeindicae is a disease threat for mango in tropical and subtropical countries (Gagnevin and Pruvost 2001). X. citri pv. mangiferaeindicae causes severe infection in a wide range of mango cultivars and induces slightly raised, angular, black leaf lesions, sometimes with a chlorotic halo. Severe leaf infections result in tree partial defoliation. Fruit symptoms appear as small water-soaked spots around lenticels. These spots later become star shaped, erumpent, and exude an infectious gum. Severe fruit infections cause premature fruit drop, which can reach 80% on susceptible cultivars. Twig cankers are potential sources of inoculum and weaken resistance of branches to wind damage (Gagnevin and Pruvost 2001). Mango leaves showing typical angular, black, raised leaf lesions were first observed and collected in June 2014 in the major mango-growing areas of Bénin (Atacora, Borgou, and Collines). Nonpigmented Xanthomonas-like colonies were isolated on KC semiselective medium (Pruvost et al. 2005). Seven strains from Benin (LL142, LL143, LL145, LL148, LL149, LL151, and LL152) were compared by multilocus sequence analysis (MLSA) 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 (Bui Thi Ngoc et al. 2010). Nucleotide sequences were 100% identical to those of the pathotype strain of X. citri pv. mangiferaeindicae whatever the gene assayed (GenBank Accessions Nos. EU015189, EU015281, EU015373, and FJ376236), but differed from any other assayed X. citri pathovar. Hardened leaves of mango cv. Maison Rouge from the youngest vegetative flush were infiltrated (10 inoculation sites per leaf for three replicate leaves on different plants per bacterial strain) with the same seven Beninese strains. Bacterial suspensions (?1 × 105 CFU/ml) were

Mots-clés : xanthomonas campestris citri; mangifera indica; Étiologie; bénin; xanthomonas citri pv mangiferaeindicae

Thématique : Maladies des plantes

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