|Luster, Douglas - Doug|
Submitted to: Biological Control
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/27/2003
Publication Date: 1/20/2004
Citation: Yourman, L.F. and Luster, D.G. 2004. Generation of molecular markers for the identification of isolates of Puccinia jaceae, a potential biological control agent of yellow starthistle. Biological Control 29:73-80. Interpretive Summary: Weeds that have been accidentally introduced into the U.S. cause large annual losses to farmers and ranchers. In particular, weeds such as yellow starthistles (YST) that invade cattle grazing lands which have a low profit margin, are not manageable with conventional chemical weed killers. Our laboratory seeks biological control agents for control of invasive weeds. This manuscript describes research to define molecular markers for fungi studied for biological control of yellow starthistle. We are identifying and testing the specificity of markers that will help us to follow the biological control agents once they are released into the environment. This research will help regulatory agencies to assess the risk of such releases, and will allow researchers to track the biological control agent in the field upon release into the environment.
Technical Abstract: Yellow starthistle (Centaurea solstitialis L.) is an important invasive weed that infests large tracts of land in the western United States and Canada. The exotic fungal rust pathogen Puccinia jaceae has been evaluated in our laboratory as a potential biological control for yellow starthistle. The objectives of this study were to determine the genetic variability among P. jaceae isolates from different Centaurea spp. hosts by AFLP DNA fingerprint analysis and to determine the genetic variability among several generations of P. jaceae isolate 8471, an isolate from Turkey previously identified as virulent on yellow starthistle. AFLP analysis indicated that individual Eurasian isolates of P. jaceae from different hosts exhibited unique fingerprint patterns. Similarity clusters were formed among isolates primarily based on host (pathogenicity) preference. Three isolates of P. jaceae collected from diseased C. calcitrapa (purple starthistle) plants clustered together with a bootstrap value of 96%; three isolates originally from yellow starthistle clustered together with a bootstrap value of 94%; an internal node connected one isolate from C. diffusa (diffuse knapweed) with a bootstrap value of 97%. Urediniospores from four additional, and successive, generations of isolate 8471 were also harvested from infected yellow starthistle plants and analyzed. Similarity of AFLP patterns among spores from successive generations ranged from 79.2% to 86.8%. An AFLP marker fragment of 182 bp associated with the unique AFLP fingerprint of isolate 8471 was identified in all five generations of the isolate and may be useful in the development of future rapid identification methods for the isolate.