COMPARISON OF ISOZYME AND RANDOM AMPLIFIED POLYMORPHIC DNA DATA FOR DETERMINING INTRASPECIFIC VARIATION IN CUCUMIS

Variation at isozyme and random amplified polymorphic DNA (RAPD) loci in eight cucumber and seven melon cultivars, breeding lines, and plant introductions were used to determine the utility of these markers for assessing genetic variation among populations of each species. Althou gh dendrograms derived from cluster analyses using species' variation at marker loci were dissimilar, these disparities were consistent with differences in the pedigrees and/or other information (e.g., morpholo gical) known about each accession and species. Empirical estimations o f variances associated with each marker type in the cucumber and melon accessions examined indicate that, per band, lower coefficients of va riation can be attained in the estimation of genetic difference when u sing RAPDs compared to isozymes. The disparity between the marker anal yses made may be related to the amount of genome coverage characterist ic of a particular marker system in a species and its efficiency in sa mpling variation in a population.