Location: Sugarcane Field StationTitle: First Report of Orange Rust of Sugarcane Caused by Puccinia kuehnii in Ivory Coast and Cameroon Author
Submitted to: Plant Disease
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/13/2010
Publication Date: 3/1/2011
Citation: Saumtally, S.A., Viremouneix, T.R., Ahondokpê, B., Girard, J.R., Castlebury, L.A., Dixon, L., Glynn, N.C., and Comstock, J.C. First Report of Orange Rust of Sugarcane Caused by Puccinia kuehnii in Ivory Coast and Cameroon. Plant Dis. 95:357. 2011. Interpretive Summary: With the confirmation of sugarcane orange rust in the West African countries of Cameroon and the Ivory Coast; this is a possible source of origin of the pathogen, Puccinia kuehnii to Florida and the Western Hemisphere. Sugarcane orange rust was first detected in Florida in 2007 the first detection of the disease in the Western Hemisphere. Although sugarcane brown rust is believed to have been originated from Cameroon, there had been no confirmed reports of sugarcane orange rust in Africa. Through scientific contacts sugarcane rust samples were obtained and confirmed the presence of the orange rust pathogen, Puccinia kuehnii, in Cameroon and the Ivory Coast indicting a possible source of origin of sugarcane orange rust pathogen to the Western Hemisphere. A comparison of the DNA molecular sequences between P. kuehnii isolates between Africa and the Western Hemisphere needs to done to substantiate this.
Technical Abstract: Orange rust of sugarcane caused by Puccinia kuehnii was detected in Florida in 2007. It was hypothesized that the pathogen originated from Africa because brown rust of sugarcane (syn. common rust) was introduced to the Western Hemisphere from Africa. Requests for rust infected sugarcane samples were made to several Western and Central African countries to investigate if orange rust of sugarcane was present but as yet undetected. Orange rust had not previously been reported from Western or Central Africa. At Zuénoula, Ivory Coast in July 2009, symptoms of sugarcane rust were observed on cultivars SP 71-6180 and Co 997 and appeared distinct to those of brown rust of sugarcane. A year later in May 2010, rust infected specimens of SP 71-6180 and Co 997 from the same location and also from Borotou in Ivory Coast were sent to the USDA-ARS Systematic Mycology and Microbiology Laboratory in Beltsville, MD for identification. Also, in May 2010, sugarcane rust was observed at Mbandjock and Nkoteng in Cameroon on cultivars D 88172, FR 87482 and RB 72-454, and on breeding clones RCmr 07/319 and RCmr 07/1121. All specimens showed morphological characteristics consistent with orange rust of sugarcane, described in detail in (2). DNA isolated from all samples was successfully amplified with P. kuehnii specific primers targeting ITS1 of rDNA (3). The ITS2 and 5’ nuclear large subunit rDNA region of the rust specimens from Ivory Coast (BPI XXXX GenBank Accession No.XXX) and Cameroon (GenBank Accession No. XXXX) were sequenced. DNA sequences for all were identical to sequences of P. kuehnii and distinct from known sequences of P. melanocephala available in GenBank. To our knowledge this is the first confirmed report of orange rust of sugarcane in Western and Central Africa. 1. Comstock, J.C., et al. Plant Dis. 92:175. 2008. 2. Glynn, N.C., et al. Plant Pathology. 59:703-711. 2010.