The Random Amplified Polymorphic DNA (RAPD) technique appears useful for
genetic purity testing and variety discrimination for several crops. It is simple, fast, relatively
inexpensive and allows the use of DNA extracted from dry seeds, which is important in a seedquality
testing program. This genetic purity testing approach may be very attractive for species
such as vinca (Catharanthus roseus (L.) G.Don) because little is known concerning the DNA
sequence and a number of commercial primers can be utilized to achieve polymorphic banding
patterns to discriminate genotypes. However, in this study, RAPD banding patterns obtained from
bulked vinca seed were not consistent. Similar inconsistent results were found for RAPD banding
patterns of individual vinca seeds from the same cultivar. Thus, the low stringency requirements
of RAPDs may be responsible for these irreproducible and unexpected results. In addition, this
highly sensitive technique still requires further standardization of test protocol. These findings
suggest that RAPD fragments obtained on electrophoretic gels are not applicable for genetic purity
testing and variety discrimination in vinca flower seeds. However, RAPD banding patterns acquired
from seedling leaf tissue of vinca were more reproducible.