Genetic Diversity inBrassica oleraceaL. (Cruciferae) and Wild Relatives (2n=18) using Isozymes

Genetic diversity in 36 populations of wild taxa of theBrassicaoleraceaL. group (2n=18) and two cultivated forms was studiedusing isozyme variation at 11 loci for five enzyme systems (IDH,6-PGD, PGM, PGI, MDH). Mean values for the percentage of polymorphicloci and expected heterozygosity were 54% and 0.224, respectively.Statistically significant differences among allele frequencieswere found with the 6-PGD isozyme system. Intrapopulationalgenetic diversity was 67% while interpopulational genetic diversitywas only 33%. The dendrogram obtained, using genetic distancesamong taxa, showed three different groups. With the exceptionofB. incana,they agree to the already accepted relationshipsamong the 14 taxa studied: the West Mediterranean group, withB.oleracea, B. alboglabra, B. bourgeauiandB. incana; another groupof species growing in the central Mediterranean area, whichincludesB. villosa, B. villosasubsp.drepanensis, B. rupestris,B. macrocarpa(the four taxa together withB. incanaare consideredtheB. rupestrisgroup) andB. montana; and finally the Aegeangroup, which includes the three subspecies ofB. cretica.Clearlyseparated wereB. insularisandB. hilarionis, showing the maximumgenetic distance. Separate dendrograms were also obtained forB.oleracea, B. montana, B. creticaandB. rupestrisgroup, and geneticdiversity parameters were estimated. Genetic distances amongB.oleraceapopulations are in the same range as populations oftheB. creticasubspecies. Highest genetic distances were foundamong populations of theB. rupestrisgroup.Copyright 1998 Annalsof Botany Company. Brassica oleraceaL., wild relatives, genetic diversity, genetic resources, isozymes.