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 - 2.46

MORPHOLOGICAL AND MOLECULAR CHARACTERISATION OF TOMATO (LYCOPERSICON ESCULENTUM MILL.) LANDRACES FROM CENTRAL ITALY

A. Mazzucato*, E. Bitocchi**, P. Mosconi*, L. Nanni**, V. Negri***, R. Papa**, M.E. Picarella*, G.P. Soressi*, B. Tiranti***, F. Veronesi***

*) Dip. di Agrobiologia e Agrochimica, Univ. degli Studi della Tuscia, Viterbo, Italy

**) Dip di Biotecnologie Agrarie ed Ambientali, Univ. Politecnica delle Marche, Ancona, Italy

***) Dip. di Biologia vegetale e Biotecn. Agro-ambientali, Univ. degli Studi di Perugia, Perugia, Italy

genetic diversity, germplasm, landraces, tomato

In tomato, as in several vegetable crops, Italian farmers have kept a rich heritage of autochthonous landraces that are still widely adopted in small-scale cultivations and consumed in local markets. However, the widening use of F₁ hybrids, the decreasing practice of home consumption cultivations and the lack of commercial interest for seed production of these local types are threatening their survivor and the maintenance of their genetic integrity. In this scenario, the study of phenotypic and genetic diversity is important for conserving, evaluating and utilizing genetic resources as well as for determining the uniqueness and distinctness of landrace genotypes in the perspective of their conservation.

In this research, a collection of tomato landraces mainly gathered in Central Italy in local projects by the Universities of Ancona, Perugia and Viterbo, has been grown and characterised at the morphological, physiological and molecular level. The collection included 57 accession of landraces collected from the farmers (43 from Central Italy), 5 vintage cultivars, 8 accessions of commercially available landraces and two wild outgroups. The landraces were highly diversified as for fruit size, shape and destination.

From 10 plants per accession, raised with standard cultural practices, more than 20 morpho-physiological descriptors have been evaluated together with overall susceptibility to diseases and physiological disorders. One plant per accession, controlled a posteriori for being conform to the expected typology, were analysed with 10 Simple Sequence Repeats (SSR) markers selected from those described in literature and located in both coding and non coding genomic regions.

Descriptive, univariate as well as multivariate statistics were independently worked out for the morpho-physiological and molecular dataset that, nonetheless, deserve both to be integrated in the future. The first observations on morphological traits detected heterogeneity in some landraces and showed the presence of clear off-types in commercial seed lots of local types, indicating that often genetic purity is not a property of both the material conserved by the farmers and that produced by seed companies.

At the molecular level, 10 SSR loci produced in total 48 alleles, whit the number of alleles per locus ranging from 2 to 12. Among SSR loci, the level of genetic diversity measured as expected eterozygosity (He) varied between He=0.07 and He=0.82 with an average value of He=0.40. Observed heterozygosity (Ho) was Ho=0 for four loci while for the other six it ranged between Ho=0.02 and Ho=0.17 with an average value of Ho=0.03. These data indicate a large among locus variation for the level of genetic diversity. This result can be related to the different genomic regions considered. In particular the different loci may be differentially influenced by selection or present a different mutation rate.

Based on SSR data, all the individual analysed were found to be different genotypes with the exception of the “Scatolone di Bolsena” accessions and of two “A pera” accessions. Multivariate analyses generally grouped the landraces into clusters based on fruit characters giving interesting insights as, for instance, the relationship between the “Scatolone di Bolsena”, the “Pantano romanesco” and the “Costoluto fiorentino” types and the cv. Marmande or that between the “Ciliegino” types and the wild taxon L. esculentum var. cerasiforme.

“This research is supported by MIUR in the framework of the project SCRIGNO (Sviluppo e caratterizzazione delle risorse genetiche nativein ortofrutticoltura)”