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 - 2.16

MICROSATELLITE DNA SEQUENCES AND VARIETAL IDENTIFICATION IN OLIVE

V. SARRI*, A. CONTENTO*, M. FREDIANI**, L. BALDONI*** , P.G. CIONINI*

*) Dipartimento di Biologia Cellulare e Molecolare della Università di Perugia, Sezione di Citologia e Genetica, Via A. Pascoli, 06123 Perugia, Italy

**) Dipartimento di Agrobiologia e Agrochimica, Università della Tuscia, Via S. Camillo de Lellis, 01100 Viterbo, Italy

***) CNR, Istituto di Genetica Agraria, Divisione Ricerca di Perugia, Via Madonna Alta 130, 06128 Perugia, Italy

microsatellite DNA sequences, olive, varietal identification

Olea europaea L., the olive, is one of the oldest tree crops, and its agricultural interest is very remarkable in Italy and in the countries of the Mediterranean Basin. In spite of this, knowledge and methodologies allowing us a sure discrimination between more than 2,600 olive cultivars described are to date lacking, in spite of their importance in certifying cultivars and assessing the commercial identity of oils and their origin. Very recently, research work has been carried out in order to identify and characterize olive cultivars by the use of parameters other than the morphological and quantitative traits used up to today, which may be affected by the diversity of enviromental conditions. However, the search for reliable, cultivar-specific markers to be exploited also in identifying the cultivar/s from which an oil is originated is far from being brought to an end. As a consequence, reliable and feasible protocols for the identification of olive cultivars and then for the traceability and certification of oils are not available.

We carried out research work in an attempt to use simple sequences repeats (SSRs) in the nuclear DNA for the identification of olive cultivars, taking into account that a cultivar would represent a clone, due to vegetative propagation. SSRs isolated by us from a DNA library or found in the literature were tested for their capability to give polymorphic products when amplified by polymerase chain reaction in different olive genotypes. SSRs able to produce high polymorphism were selected and amplified in 78 olive cultivars from Italy and the other Mediterranean countries. The amplification products were run in 3% sucrose gels and the electrophoretograms were registered. Sucrose gels were chosen, in view of the possible applied exploitation of the method, since they are safe, easy and economical.

We found that the band patterns obtained by summing up the band patterns produced by each of three microsatellite sequences (ssrOeUA-DCA9, ssrOeUA-DCA16, and ssrOeUA-DCA17; Sefc et al., Molecular Ecology (2000) 9, 1171-1193) were unique for 67 out of 78 genotypes studied. Other genotypes could be distinguished by adding the band pattern obtained by using a fourth microsatellite sequence (ssrOeUA-DCA11; Sefc et al., l.c.). Within each of five groups, the cultivars showed the same band patterns. These cultivars are known to represent synonyms, as was confirmed by analyzing their genotypes by AFLP. Plant grown in different environments but belonging to same cultivars showed the same band patterns. Therefore, by using four selected SSRs, ‘bar codes’ were obtained which identify with certainty olive cultivars and can recognize homonymies and synonymies.

Work is in progress to try the assessment of the origin and commercial identity of olive oils by characterizing extracted DNAs by the above method.