Screening RAPD primers for molecular taxonomy and cultivar fingerprinting in the genus Actinidia

Eighty ten-base long arbitrary primers were tested for PCR- based DNA amplification of three species of the genus Actinidia (A. deliciosa the kiwifruit, A. chinensis, and A. kolomikta), with the aim of screening species-specific and genotype-specific markers. Of the 80 primers tested, 30 gave an average of 3.5 bands which were monomorphic within one or two species and absent in the remaining one(s), thus resulting in useful markers for taxonomic and phylogenetic purposes. None of the primers tested produced bands linked to sex. Twenty primers out of the twenty-five selected from a preliminary screening showed high levels of polymorphism, producing two to eleven patterns each from the 13 kiwifruit cultivars examined. We found the Stoffel fragment and the Taq polymerase were both suitable for RAPD analysis, the most noticeable difference being the smaller size of fragments (0.4-1.2 kb) produced by the former in comparison to the latter (1.03.4 kb). We tested also three different annealing temperatures (35, 37, and 39° C) and found the intermediate one best for number of amplified bands and reproducibility of results.