Proceedings of the XLVII Italian Society of Agricultural Genetics - SIGA Annual Congress

Verona, Italy - 24/27 September, 2003

ISBN 88-900622-4-X

Poster Abstract - 3.17

Genetic characterization of native germplasm of Salix alba L. from Brenta river for multiple use land reclamation

S. Meneghetti*, G. Barcaccia*, P. Paiero**, M. Lucchin*

*) Dipartimento di Agronomia Ambientale e Produzioni Vegetali, Università di Padova – Agripolis, via Romea 16, 35020 Legnaro, Padova, Italy

margherita.lucchin@unipd.it

**) Dipartimento Territorio e Sistemi Agroforestali (TESAF), Università di Padova.

Salix alba, AFLP, genetic variability, linkage disequilibrium

Environmental exploitation has profoundly affected the quality of the landscape and its natural features, disturbing the ecological balance and destroying important habitats. However, a stronger concern is finally arising for a better management of the landscape; tree woodlands, natural sites are more and more considered for their natural and multiple use values.

Recently, many projects have been developed to rebuild a woody vegetation cover on disturbed or marginal sites, with both an environmental and a multiple use purpose. A careful selection of species and populations to use, on the basis of an accurate ecological and genetic evaluation, is necessary to guarantee that good results are obtained.

Our research deals with the evaluation of genetic variability in natural populations of Salix alba L., a colonising tree species, from the middle course of Brenta river (North-East Italy) and the study of relationships between genetic and morphological variation in order to detect some chromosomal regions affecting quantitative traits. A comparative characterization of three natural populations of S. alba from Fontaniva (VI), Carturo (PD) and Piazzola sul Brenta (PD) was carried out using AFLP molecular markers.

Selected primer combinations generated a total of 276 amplified products, 178 of which showed to be polymorphic (64.5 %). The Shannon’s diversity information index over populations and AFLP loci was I = 0.251. The mean Dice’s genetic similarity coefficients within and between populations were similar and equal respectively to 0.887 and 0.885; the same was true for the mean genetic distances that were respectively 0.120 and 0.122. These results were in agreement with the amount and the partition of genetic diversity. The total Nei's genetic diversity was H_T = 0.159, while that calculated for single populations was, on average, H_S = 0.151. The extent of differentiation between populations was G_ST = 0.050 showing that as much as 95% of the total genetic variability observed can be attributed to within-population differences and only 5% is due to differences among the three populations, as confirmed by the high estimated value of gene flow (Nm = 9.50).

Relationships between molecular polymorphisms and phenotypic variation in traits were assessed by the detection of linkage disequilibrium between selected AFLP loci. Significant (P<0.05) pair-wise linkage disequilibria were found for all the morphological traits but stem diameter. The number of linkage disequilibria was ranging from 1 of both stem straightness and stem inclination to 4 of stem taper. On the whole 12 significant pair-wise linkage disequilibria were found. These results, together with the R² coefficients of multiple regression analyses ranging from 0.22 to 0.46, allowed to identify some chromosomal regions where QTLs supporting large phenotypic effects are located.