Evolution of the genetic structure in Tricticum Durum Desf. germplasm from Southern Italy.

The thesis that modern plant breeding has led to loss of genetic diversity in durum wheat (Triticum durum Desf.) has often been supported. Since the “Green Revolution”, a huge number of durum wheat variety have been obtained by artificial selection, generally based on high yield, disease resistance and technological qualities. On the other hand, at the same time, traditional local varieties have been considerably reduced. The evaluation of diversity at morphological and molecular level can be used to reveal temporal trends of diversity among different historical classes of durum wheat germplasm and to help in the selection of materials that need to be conserved. A set of 107 durum wheat accessions collected in Southern Italy starting from the 1947 up to year 2009 was analyzed at the University of Basilicata by 22 quanti-qualitative morphological traits and 30 nuSSRs. The accessions were grouped into two temporal groups on the basis of their collection date (1947-1951 and 1973-2009) in order to study the genetic structure changes that occurred over time. Morphological traits, particularly quantitative ones, revealed a high level of variability and showed a significative differentiation among the two groups. High polymorphism was observed for SSR, with a total of 115 alleles identified and an average of 3,83 alleles per locus. While in some loci one or more alleles were gained between the first and the second group, in other cases the allelic constitution at loci remained constant. The use of morphological traits and molecular markers revealed of great utility in assessing temporal trends in the diversity of Southern Italy durum wheat germplasm. The results indicated that the impact of breeding systems did not lead to any significant quantitative losses of genetic diversity in the set of accessions over the two temporal groups