A SURVEY OF DNA POLYMORPHISM WITHIN THE GENUS CAPSICUM AND THE FINGERPRINTING OF PEPPER CULTIVARS

Interspecific genetic variation was examined in the genus Capsicum bas ed on shared restriction fragments in Southern analyses. Four distinct clusters were delineated among 21 accessions of cultivated and wild p epper (C. annuum, C. baccatum, C. chacoense, C. chinense, and C. frute scens). Three tight clusters comprised of accessions belonging to C. a nnuum, C. frutescens, and C. baccatum, respectively, were formed, alon g with a fourth cluster comprised of one accession each of C. chinense and C. chacoense. All accessions were differentiated by this techniqu e, and the clusters corresponded closely to previous morphology-based classification. Sufficient DNA polymorphism exists among these accessi ons that segregating populations useful for restriction fragment lengt h polymorphism (RFLP) mapping could be constructed using any two peppe r accessions as parents. Regression analysis indicates that genetic di stance is a good predictor (R(2) = 0.872) of the level of mappable DNA polymorphism in Capsicum. Intraspecific variability was examined amon g four C. annuum cultivars (NuMex R Naky, Jupiter, Perennial, and Crio llo de Morelos 334) using both RFLPs and randomly amplified polymorphi c DNA (RAPDs), allowing a comparative evaluation of the two techniques . Seventeen percent of the clones used singly in RFLP analyses were su fficient for the differentiation of these varieties, as were 12.5% of the RAPD PCR amplifications. Dendrograms constructed from RFLP and RAP D analyses of the intraspecific data are similar but not identical. So uthern analysis and RAPD PCR should be useful for DNA fingerprinting a nd the discrimination of closely related C. annuum genotypes.