ARS | Publication request: Spread, genetic variation and methods for the detection of Puccinia kuehnii, the causal agent of sugarcane orange rust.

Submitted to: APS Annual Meeting
Publication Type: Abstract Only
Publication Acceptance Date: April 7, 2009
Publication Date: January 14, 2010
Citation: Glynn, N.C., Castlebury, L.A., Dixon, L.J., Comstock, J.C. Spread, genetic variation and methods for the detection of Puccinia kuehnii, the causal agent of sugarcane orange rust.. APS Annual Meeting. Paper

Technical Abstract: Sugarcane is susceptible to infection by two rust pathogens, Puccinia melanocephala and P. kuehnii, causing brown and orange rust, respectively. Orange rust of sugarcane was first reported in the Western hemisphere in Florida in July 2007. The pathogen was found to be distributed widely throughout the sugarcane growing area of Florida and subsequently has been found to be widespread among Central American and Caribbean sugarcane growing areas. The identity of P. kuehnii was confirmed using morphological characters and sequence analysis of portions of rDNA. The rDNA sequences from isolates from regions of South East Asia and Australia, where the pathogen has been prevalent historically contained a single nucleotide polymorphism with two alleles. Only one of these alleles was detected in isolates from the newly reported areas in the Western hemisphere suggesting a single introduction to the region. Real-time PCR methods for the detection and quantification of P. kuehnii DNA and the discrimination of the two alleles and from the closely related sugarcane rust pathogen P. melanocephala are presented. These rapid methods for identifying the pathogen will allow monitoring of the spread of P. kuehnii to parts of the Western Hemisphere under threat from infection.