Using RAPD markers to identify genets of an arable grass weed, Arrhenatherum elatius ssp. bulbosum

RAPD (Random Amplified Polymorphic DNA) markers were used to identify genets within a weed infestation of Arrhenatherum elatius ssp bulbosum (''onion couch''). Three selected primers could discriminate between 18 sexually-derived plants of A. elatius ssp. elatius. Using these primers, RAPD phenotypes were obtained for ramets of ssp. bulbosum from a population of unknown sexual derivation, i.e. predominantly sexual or vegetative. Thirty three RAPD phenotypes were observed amongst 65 plants. Ramets with identical RAPD phenotypes were termed ''genets''. Some genets of ssp. bulbosum were found in localised patches, whereas others had much wider ranges, indicating long-distance dispersal by farm machinery. RAPD markers provide a useful tool for discriminating between genets within an established plant population.