First Report of Cassava Bacterial Blight Caused by Xanthomonas axonopodis pv. manihotis in Burkina Faso

Abstract

HomePlant DiseaseVol. 99, No. 4First Report of Cassava Bacterial Blight Caused by Xanthomonas axonopodis pv. manihotis in Burkina Faso PreviousNext DISEASE NOTES OPENOpen Access licenseFirst Report of Cassava Bacterial Blight Caused by Xanthomonas axonopodis pv. manihotis in Burkina FasoI. Wonni, L. Ouedraogo, S. Dao, C. Tekete, O. Koita, G. Taghouti, P. Portier, B. Szurek, and V. VerdierI. WonniSearch for more papers by this author, L. OuedraogoSearch for more papers by this author, S. DaoSearch for more papers by this author, C. TeketeSearch for more papers by this author, O. KoitaSearch for more papers by this author, G. TaghoutiSearch for more papers by this author, P. PortierSearch for more papers by this author, B. SzurekSearch for more papers by this author, and V. VerdierSearch for more papers by this authorAffiliationsAuthors and Affiliations I. Wonni L. Ouedraogo , INERA Farako-Ba, Bobo-Dioulasso, Burkina-Faso S. Dao C. Tekete O. Koita , Université des Sciences Techniques et Technologiques, Faculté des Sciences et Techniques, LBMA, Bamako, Mali G. Taghouti P. Portier , CIRM-CFBP, UMR 1345 IRHS INRA, ACO, UA, 49070 Beaucouzé Cedex, France B. Szurek V. Verdier , UMR186, Interactions Plantes Microorganismes Environnement (IPME), IRD-Cirad-UM, 34394 Montpellier Cedex 5, France. Published Online:1 Apr 2015https://doi.org/10.1094/PDIS-03-14-0302-PDNAboutSectionsSupplemental ToolsAdd to favoritesDownload CitationsTrack Citations ShareShare onFacebookTwitterLinked InRedditEmailWechat Xanthomonas axonopodis pv. manihotis is the causal agent of cassava bacterial blight (CBB), a major disease of cassava in tropical and subtropical areas. CBB is a foliar and vascular disease characterized by angular leaf lesions, blight, wilting, stem exudates, and stem cankers. Since cassava is propagated clonally from stem cuttings, CBB plays a major role in limiting productivity, with losses between 12 and 100% affecting both yield and planting material. In August of 2011 and October of 2012, CBB symptoms were observed on 10-month-old field cassava grown in Bonfeba and in Takeledougou, Burkina-Faso (Cascades region). Symptoms consisted of angular, water-soaked leaf lesions, wilt, and visible exudates on the stem. White Xanthomonas-like strains were isolated from leaf tissues on LPGA medium (yeast, 5 g; peptone, 5 g; glucose, 5 g; bacto agar, 15 g; and distilled water, 1,000 ml). A PCR assay developed for the identification of X. axonopodis pv. manihotis (2) was used to determine the identity of Xanthomonas-like strains. X. axonopodis pv. manihotis strain CFBP7661 was used as a positive control. The expected DNA fragment (898 bp) was obtained from all the strains. No fragment was observed for negative controls (distilled water as the template). Three X. axoponodis pv. manihotis strains were further analyzed by sequence analysis using the gyrB and rpoD housekeeping genes. Comparison of rpoD and gyrB sequences showed that strains were 99 to 100% identical to 65 different strains of X. axonopodis pv. manihotis. Pathogenicity tests were performed on greenhouse-grown 4-week-old cassava plants, cv. MCOL 1522. Cultures were grown overnight in LPGA medium, adjusted in sterile water to 1 × 108 CFU/ml, and inoculated into cassava leaves and stems as previously described (1). Control plants were inoculated with sterile water. X. axonopodis pv. manihotis strain CFBP7661 was used as a positive control. After 7 days of incubation in the greenhouse at 28 ± 1°C with a 12-h photoperiod, inoculated leaves developed water-soaked lesions. Wilted leaves and stem exudates were visible at 30 days after stem inoculation. Symptoms were identical to those seen in the field. Control plants remained symptomless. Koch’s postulates were fulfilled after re-isolation of Xanthomonas-like white strains from leaf symptoms on inoculated cassava and confirmation as X. axonopodis pv. manihotis by PCR assay as described above. Three strains (CFBP7945, CFBP7946, CFBP7947) were deposited in the French Collection for Plant-Associated Bacteria (CIRM-CFBP). Information on Xam strains as well as gyrB and rpoD sequences are available through CIRM-CFBP http://www6.inra.fr/cirm_eng/CFBP-Plant-Associated-Bacteria. To our knowledge, this is the first report of CBB in Burkina Faso. Since cassava is becoming a crop of importance for human consumption in Burkina-Faso, CBB may limit productivity. Further surveys will be necessary to evaluate the geographic distribution and prevalence of CBB in Burkina-Faso and neighboring countries.