312 Session 7 Ecological and Evolutionary Processes Utility of Microsatellite Markers from the Wheat Genetic Map in the Genome of Medusahead Rye (Taeniatherum caput-medusae) B. G. Rector, M. C. Ashley and W. S. Longland USDA-ARS Exotic and Invasive Weeds Research Unit, 920 Valley Road, Reno, NV 89512 USA [email protected] [email protected] [email protected] Abstract Medusahead rye (Taeniatherum caput-medusae (L.) Nevski) is a winter annual grass that is native to Eurasia and invasive in western North America. DNA markers were desired to facilitate the study of medusahead population genetics as well as for analysis of the inheritance of key traits. In this study we demonstrate the utility of PCR-based microsatellite markers (SSRs) from the wheat genome as polymorphic genetic markers in the medusahead genome. In a preliminary screen of 37 wheat SSRs taken from across the three wheat genomes (A, B, and D), 19 wheat SSR primer pairs (51%) successfully amplified bands from medusahead template DNA. From these 19 markers, 12 of which produced multiple bands, 40 polymorphic bands have been scored among a group of six medusahead populations from NW Nevada and NE California. Wheat SSRs from the A genome, which is more closely related to medusahead phylogenetically than the B or D genomes, were no more likely to amplify than SSRs from the other wheat genomes. This study shows that intergeneric use of existing PCR-based genetic markers can provide an inexpensive source of molecular genetic tools for study of invasive weed species, particularly those that are closely related to economically important plant species with established genomic resources. XIII International Symposium on Biological Control of Weeds - 2011.