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 seed-quality 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.
vinca; seeds; varieties; molecular markers
