Morphological and molecular characterization of Puccinia kuehnii, the causal agent of orange rust, in Cuba

BERTANI, R; PERERA, M. F.; ARIAS, M.E; HECHAVARRÍA, MARÍA DE LA LUZ LA O

Congreso; ISSCT XXX Congress; 2019

In Cuba, no studies have characterized Puccinia kuehnii. The aims of this study were to morphologically describe P. kuehnii isolates from Cuba, estimate its genetic diversity and determine its infection mode in sugarcane. Sugarcane samples with orange rust symptoms were collected in Cuba and identity was verified by species-specific PCR. Cross sections of leaves and spores harvested from pustules were analyzed morphologically. Total DNA of the spores was characterized by AFLP and SSR markers and by sequencing rDNA. All samples showed typical lesions of P. kuehnii: pustules were mainly located on the abaxial epidermis of leaves. The urediniospores varied in shape, color and size. Some spores displayed a uniform wall thickness and they were moderately echinulate. AFLP markers were useful to characterize P. kuehnii, as they detected a high diversity. SSR markers designed for P. melanocephala could not be transferred to P. kuehnii and rDNA sequences did not reveal differences between isolates. Spines were detected as a new entry site in sugarcane. Morphological and molecular characterization showed no apparent correlation among isolates and sugarcane clones, locations and collection dates and this entire characterization suggested that there is a single, but highly diverse and complex pathogen population.