Generation of molecular markers for the identification of isolates of Puccinia jaceae, a potential biological control agent of yellow starthistle

Yellow starthistle (Centaurea solstitialis L.) (YST) is an important invasive plant that infests millions of hectares in the western USA and Canada. Isolates of the exotic rust fungus Puccinia jaceae have been evaluated as a potential biological control for YST. The objectives of this study were to characterize isolates of P. jaceae by amplified fragment length polymorphic (AFLP) DNA analysis and to develop primers that will allow the identification and monitoring of isolates. AFLP analysis indicated that Eurasian isolates of P. jaceae from different hosts exhibited unique fingerprint patterns primarily based on host/pathogenicity preference. Overall similarities in AFLP profiles of isolates of P. jaceae ranged from 68.1 to 94.6%. The three isolates originally collected from YST clustered with similarities of 87.3–94.6%. Simple sequence repeat (SSR) primers were screened for fragments unique to P. jaceae pathogens of YST. Two primers, (GACA)4 and (ACG)5, produced 1170 and 912-bp fragments, respectively, in three isolates of P. jaceae var. solstitialis. The fragments were sequenced, and primers were designed and tested with isolates of Puccinia spp. and accessions of Centaurea spp. Primers from the GACA repeat amplified a 1091-bp product only with the three isolates of P. jaceae that infect YST. Primers from the ACG repeat amplified a 851-bp product with the same three P. jaceae var. solstitialis isolates, and an isolate collected from Centaurea maculosa, which is a weak pathogen of YST. These primers will be useful for monitoring isolates that may be released in future field trials to manage YST populations. [Copyright &y& Elsevier]