Comparative Molecular Analysis of Winter Wheat Cultivars and Their Doubled Haploid Derivatives

Abstract

Genetic stability of doubled haploid (DH) lines of androgenetic origin is the prerequisite of their breeding value. In our investigations GK Gobe: a traditional cultivar, GK Delibab: a cultivar of doubled haploid origin, various 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. High molecular weight DNA was isolated from randomly selected individuals of these groups and analysed by RAPD, SSR and AFLP methods. The objective of these analyses was to determine the existence or magnitude of difference between cultivars produced by classical and haploid methods (populations are represented by the individuals of each group), and to find which marker system would be most suitable to investigate the homogeneity of DH populations. From the 30 RAPD primers tested, only 6 differentiated the two cultivars (GK Gobe and Delibab). Individual polymorphism could not be observed. There were 7 fragments generated on 12 loci with 9 SSR primers, which were suitable 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 suitable to show differences, resulting in an average of 100–150 fragments. Eighty-one polymorphic fragments were obtained with these 7 primer combinations. Twenty-three of the 81 polymorphic (bands) markers could detect individual 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). This result is probably due to repeated application of haploidization techniques. Presumably, the repeated DH production increased the level of homogeneity, as suggested by the significant decrease of the number of polymorphic bands in the second cycle DH lines. Each group consists of individuals, which can be genetically considered as progeny mixture of homozygous recombinants used for the establishment of the given population. Differences between the DH lines of one cultivar may be due to the consequences of the gametoclonal variation, which is fixed at individual level in the homozygous (DH) genome.