Morphological and molecular characterization of Puccinia kuehnii Cuban isolates.

BERTANI, R.P., PERERA, M.F., ARIAS, M.E., LAO HECHAVARRÍA, M., ZARDÓN NAVARRO, M.A., DEBES, M.A., LUQUE, A.C., ALONSO TERRY, E.I., RODRIGUEZ LEMA, E.I., CUENYA, M.I., ACEVEDO ROJAS, R., PLOPER, L.D. AND CASTAGNARO, A.P.

Workshop; ISSCT (International Society of Sugar Cane Technologist) XI Pathology and IX Entomology Workshops; 2015

Orange rust (Pucciniakuehnii) is a widespreadsugarcane disease, known to have devastating impacts on the crop. Although themost effective way to control rust diseases is the use of resistant varieties, durabilityof resistance is conditioned by several factors including pathogen genetics. InCuba, where orange rust is a relatively new disease and environmentalconditions favor infection, there have not been previous studies characterizingthe pathogen. The aims of this study were to establish morphological charactersthat could best describe and differentiate P.kuehnii isolates collected throughout different growing seasons and locationsin Cuba, and to set an adequate molecular technique for estimating P. kuehnii genetic diversity. All samplesshowed typical lesions by P. kuehnii:pustules were located on the abaxial epidermis of leaves and, to a lesserdegree, on their adaxial surface in some of the analyzed sugarcane genotypes.In addition, new morphologicalfeatures associated with this pathogen were observed. Morphologicalcharacterization suggested that there is a single, but highly diverse andcomplex pathogen population, and the groups obtained showed no apparentcorrelation among isolates and sugarcane varieties, locations and collectiondates. With regard to molecular studies, AFLP markers successfully characterizedorange rust isolates and detected a higher genetic diversity than morphologicaldescriptors, showing a weak correlation between the isolates and theirgeographical origins, as well as with the sampling dates. In addition, transferabilityof Puccinia melanocephalamicrosatellite loci could not be observed for P. kuehnii. Onthe other hand, the sequences of rDNA regions did not show significantdifferences among Cuban P. kuehniiisolates. Thiswork presents a thorough characterization of P. kuehnii isolates, including morphological traits, molecularmarkers and rDNA region sequence.