RANDOMLY AMPLIFIED POLYMORPHIC DNA (RAPD) VARIATION AMONG AND WITHIN ARTICHOKE (CYNARA-SCOLYMUS L) CULTIVARS AND BREEDING POPULATIONS

The magnitude of genetic differences among and heterogeneity within gl obe artichoke cultivars is unknown, Variation among individual heads ( capitula) from three artichoke cultivars and two breeding populations were evaluated using RAPD markers, One vegetatively propagated cultiva r ('Green Globe'), two seed-propagated cultivars ('Imperial Star' and 'Big Heart') and two breeding populations were examined, Two to thirte en polymorphic bands were observed for 27 RAPD primers, which resulted in 178 scored bands. Variation was found within and among all cultiva rs, and breeding populations indicating that all five groups represent heterogeneous populations with respect to RAPD markers, The genetic r elationships among individual genotypes were estimated using the ratio of discordant bands to total bands scored, Multidimensional scaling o f the relationship matrix showed five independent clusters correspondi ng to the three cultivars and two breeding populations, The integrity of the five clusters was confirmed using pooled chi-squares for fragme nt homogeneity. Average gene diversity (Hs) was calculated for each po pulation sample, and a one-way analysis of variance showed significant differences among populations. 'Big Heart' had an Hs value equivalent to the two breeding populations, while clonally propagated 'Green Glo be' and seed propagated 'Imperial Star' had the lowest Hs values, The RAPD heterogeneity observed within clonally propagated 'Green Globe' i s consistent with phenotypic variability observed for this cultivar, O verall, the results demonstrate the utility of the RAPD technique for evaluating genetic relationships and contrasting levels of genetic div ersity among populations of artichoke genotypes.