Comparative molecular analysis of winter wheat cultivars and their doubledhaploid derivatives

Genetic stability of doubled haploid (DH) lines of androgenetic origin is t he prerequisite of their breeding value. In our investigations GK Gobe: a t raditional cultivar, GK Delibab: a cultivar of doubled haploid origin, vari ous DH lines of GK Gobe (first cycle DH lines) and DH lines of GK Delibab ( second cycle DH lines) were compared with PCR-based molecular techniques. H igh molecular weight DNA was isolated fi om randomly selected individuals o f these groups and analysed by RAPD, SSR and AFLP methods. The objective of these analyses was to determine the existence or magnitude of difference b etween cultivars produced by classical and haploid methods (populations are represented by the individuals of each group), and to find which marker sy stem would be most suitable to investigate the homogeneity of DH population s. From the 30 RAPD primers tested, only 6 differentiated the two cultivars (GK Gobe and Delibab). Individual polymorphism could not be observed. Ther e were 7 fragments generated on 12 loci with 9 SSR primers, which were suit able to differentiate the two cultivars. Individual polymorphisms could not be detected between the cultivars, or within the group of first and second cycle DH lines. In the AFLP analyses, 7 of 8 primer combinations were suit able to show differences, resulting in an average of 100-150 fragments. Eig hty-one polymorphic fragments were obtained with these 7 primer combination s. Twenty-three of the 81 polymorphic (bands) markers could detect individu al differences. Nine of them were suitable to separate cultivar GK Gobe and its DH group. Based on AFLP fragments, the fewest individual polymorphisms were obtained within the DH group of GK Delibab (second cycle DH lines). T his result is probably due to repeated application of haploidization techni ques. Presumably, the repeated DH production increased the level of homogen eity, as suggested by the significant decrease of the number of polymorphic bands in the second cycle DH lines. Each group consists of individuals, wh ich can be genetically considered as progeny mixture of homozygous recombin ants used for the establishment of the given population. Differences betwee n the DH lines of one cultivar may be due to the consequences of the gameto clonal variation, which is fixed at individual level in the homozygous (DH) genome.