Research papers

Juglans regia L., phenotypic selection and assessment of genetic variation within a simulated seed orchard


Noble hardwoods are very important for the Italian furniture industry. Since 1985, approximately 170,000 ha have been planted in Italy with noble hardwoods. Among them, about 50% of species are represented by walnuts. Walnut (Juglans regia L.), not native in Italy, has been the focus of a substantial research effort for breeding and improvement programmes. The priority has been to preserve the in situ genetic resource still existing after intensive felling. Phenotypes suitable for timber production showing important traits such as straight stem, nice branch architecture, dominance and adaptation (phenology) have needed to be developed and selected. In order to reach this goals, selection of valuable progenies and the evaluation of the interaction genotype x environment, methods based essentially on a multi-trait Selection Index, were developed. Studies have been undertaken also to measure the variation of phenological traits, more correlated to traits valuable for architecture; in addition, neutral markers were used to assess genetic variation among different intensities of the adopted selections. The individual genetic component was found to be higher than at the inter-population level. Results showed that a hypothetical seed orchard made with progenies selected by morphology, phenology and genetic traits could provide material with a good performance and supply a variability similar to larger populations as the total plantation or the pseudo-natural system chosen for comparison.


Juglans regia L.; walnut; phenotypic selection; half-sib progenies; genetic variation; seed orchard

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Aletà N., Rovira M., Ninot A., Arùs P. 1993 - Inheritance of four isozymes in walnut. Hacta Horticulturae 311: 62-67.

Arulsekar S., Parfitt D.E., Mcgranahan G. 1985 - Isozyme gene markers in Juglans species. Inheritance of GPI and AAT in Juglans regia L. and Juglans hidsii. Journal of Heredity 76 (2): 103-106.

Arulsekar S., Parfitt D.E., Mcgranahan G. 1986 - Inheritance of phosphoglucomutase and esterase isozymes in Persian walnut. Journal of Heredity 77 (3): 220-221.

Barrett S.C.H. 2002 - The evolution of plant sexual diversity. Nature Reviews Genetics 3 (4): 274-284. DOI:10.1083/ngr776.

Camussi A., Möller F., Ottaviano E., Sari Sgorla M. 1986 – Metodi Statistici per la Sperimentazione Biologica. Zanichelli Ed., Bologna: 500 p.

Cavalli-Sforza L., Menozzi P., Piazza A. 1994 - Storia e geografia dei geni umani. Adelphi edizioni: 791 p.

Colletti L. 2001 - Risultati dell’applicazione del Regolamento CEE 2880/92 in Italia. Sherwood – Foreste ed Alberi Oggi 70: 23-31.

Ducci F. 1995 - Common measurements and observation form for data collection in experimental trials. Proceeding: Workshop of Groups C and D of the E.U./AIR Walnut Project, 27 -30 March 1995, Thessaloniki (Greece): 56-63.

Ducci F. 2003 - La produzione vivaistica. In: L’arboricoltura da legno: un’attività produttiva al servizio dell’ambiente. G. Minotta Ed., Av. Media, Bologna: 190-197.

El Kassaby Y.A. 1991 - Genetic variation within and among conifer population: review and evaluation of methods. In: Biochemical markers in the population genetics of forest trees.

Fineschi S., Malvolti M.E., Cannata F., Hattemer H.H. Eds., SPB Academic Publishing, The Hague, The Netherlands: 61–65.

Fady B., Ducci F., Aleta N., Becquey J., Diaz Vasquez R., Fernandez Lopez F., Jay¬Allemand C., Lefèvre F., Ninot A., Panetsos K., Paris P., Pisanelli A., Rumpf H. 2003 - Walnut demonstrates

strong genetic variability for adaptive and wood quality traits in a 415 network of juvenile field tests across Europe. New Forests 25 (3): 211-225.

Fornari B., Cannata F.¸ Spada M., Malvolti M.E. 1999 – Allozyme analysis of genetic diversity and differentiation in European and Asiatic walnut (Juglans regia L.) populations. Forest Genetics 6 (2): 115–127.

Goudet J. 2001 - FSTAT, a program to estimate and test gene diversities and fixation indices (version 2.9.3). Available From Http://Www.Unil.Chlizea/Softwares/Fstat.Html.

Hansche P.E., Beres V., Forde H.I. 1972 - Estimates of Quantitative Genetic Properties of Walnut and their Implications for Cultivar Improvement. Journal of the American Society for Horticultural Science 97 (2): 279–285.

Lande R., Kirkpatrik M. 1990 - Selection response in traits with maternal inheritance. Genetical Research 55 (3): 189 - 197.

Malvolti M.E., Finesch i S., Morgante M., Vendramin G.G. 1995 – Mating system of a naturalized Juglans regia L. population in Italy. In: Baradat Ph., Adams W.T. and Müller-Starck G. (Eds.), Population genetics and genetic conservation of forest trees. SPB Academic Publishing, Amsterdam, The Netherlands: 305–308.

Malvolti M.E., Beritognolo I., Spada M., Cannata F. 1997 – Ricerche sulle risorse genetiche e sulla biologia riproduttiva di Juglans regia L. in Italia mediante marcatori molecolari. Annali Istituto Sperimentale per la Selvicoltura XXV – XXVI (1994-1995), Arezzo: 9-34.

Michler C.H., Woeste K.E., Pijut P.M. 2007 - 6 Black Walnut. In: Genome Mapping and Molecular Breeding in Plants, vol. 7, Forest trees (C. Kole Ed.). Springer - Verlag, Berlin Heidelberg: 189-198.

Nei M. 1978 - Estimation of average heterozygosity and genetic distance from a small number of individuals. Genetics 89: 583–590.

Raymond M., Rousset F. 1995 - An exact test for population differentiation. Evolution, 49 (6): 1280-1283.

Rodriguez R., Revilla A., Albuerne M., Perez C. 1989 - Walnut (Juglans spp). In: Bajaj YPS (Ed.), Biotechnology in Agriculture and Forestry, vol. 5. Trees II. Springer-Verlag, Berlin: 99-126.

Rohlf F.J. 1994 - NTSYS, Numerical Taxonomy and Multivariate Analysis System, vers. 1.80. Exter Software – Applied Biostatistic Inc., N. Y.

Sneath P.H.A., Sokal R.R. 1973 - Numerical taxonomy. Freman, S. Francisco: 573 p.

Thiede D.A. 1998 - Maternal inheritance and its effect on adaptive evolution: a quantitative genetic analysis of maternal effects in a natural plant population. Evolution 52 (4): 998-1015. Ed Society for the Study of Evolution.

Weir B.S., Cockerham C.C. 1984 - Estimating F-statistics for the analysis of population structure. Evolution 38 (6): 1358–1370.

Wright S. 1978 - Evolution and genetics of population. Vol. 4: Variability within and among natural populations. University of Chicago Press, Chicago: 589 p.

Zobel B.J., Talbert J.T. 1984 - Applied Forest Tree Improvement. Chap. 4. John Wiley & Sons, N.Y.: 118–141

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