RAPD

Randomly amplified polymorphic DNA, a PCR fingerprinting method that works with no prior sequence knowledge. Short arbitrary primers, annealed under deliberately loose conditions, amplify a scatter of random genomic fragments into a banding pattern that distinguishes varieties, species, and strains. Researchers use these fingerprints to check cultivar identity, map genetic diversity, trace contamination sources, and characterize starter cultures. The trade-off for its speed and low cost is sensitivity: reagents, cyclers, and protocols must be rigidly standardized or the patterns will not reproduce.