Identification of essentially derived varieties in durum wheat.

Essentially derived are considered those varieties (hence EDV) that, being obtained from an original variety by means of methods that do not modify substantially its genetic structure, should be considered dependent from it. The identification of EDV is therefore an important aspect of the protection of Breeder’s Rights. It requires the definition of a threshold value of genetic conformity between the new and the original variety that, if exceeded, would provide a clue of derivation. Molecular markers-based protocols estimating genetic similarities have been proposed for EDV identification in some species, whereas no information was available for durum wheat. A set of 60 genotypes (F8- or F9- lines and their parental varieties) representing different levels of relatedness, were genotyped using 14 AFLP primer combinations (Sse8387+2-MseI+2) and 109 SSR loci evenly distributed in the genome. Jaccard similarities were calculated for all the pair-wise comparisons among entries. For both markers an EDV threshold, defined as the 95 percentile of the distribution of similarity estimates among independently developed progenies, allowed the detection of all pairs of closely related lines branched in advanced generations (F7-F8), indicating a rather good agreement of the two marker systems in evidencing cases of suspected derivation. Nevertheless, for their superior informativeness compared to SSR, AFLP appear more suitable to assess essential derivation.