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

Salsomaggiore Terme, Italy - 26/29 September, 2001

ISBN 88-900622-1-5

Oral Communication Abstract

USE OF AFLP AND SAMPL MARKERS FOR THE ANALYSIS OF THE GENETIC VARIABILITY OF THREE SHEEP GROUPS BELONGING TO THE APPENNINICA, MASSESE AND SUFFOLK BREEDS

BOGANI D.*, CAPOMACCIO S.**, CAPPELLI K.***, SARTI F.M.*

* Dipartimento di Scienze Zootecniche, Università degli Studi di Perugia, Borgo XX Giugno 74, 06121 Perugia

** Dipartimento di Biologia Vegetale e Biotecnologie Agroambientali, Borgo XX Giugno 74, 06121 Perugia

*** Dipartimento di Tecnologie e Biotecnologie delle Produzioni Animali, Università degli Studi di Perugia, Via San Costanzo 4, 06126 Perugia

sheep, AFLP, SAMPL, genetic variability, DNA

Domestic animal populations, and sheep populations in particular, are characterised by a certain level of genetic “pollution” due to the long term practice of crossing autochthonous genotypes with exotic ones. This makes assignment of individuals to a certain breed much harder, especially when there is a similar genetic derivation. The importance of a systematic approach in the definition and identification of a certain breed is becoming more compelling in a market situation where the traceability of the product seems to be an essential requisite. Moreover, the assessment of the genetic variability of certain populations is crucial in endangered breeds in order to realise breeding programs that take into account all the aspects of the problem. In such a context, molecular markers are an obvious choice, because they maximise the resolution of the genetic polymorphism or variant detection, which are the basis of the discrimination between groups or subjects. The discrimination between populations or groups is clearly crucial when the different variants are associated to desirable traits.

AFLP (Vos et al., 1995) and SAMPL (Morgante and Vogel, 1994) are ideal techniques when the genomic information on the studied species is limited. AFLPs and SAMPLs are dominant markers, but they compensate the lack of information on the homo- or heterozygous state of the analysed samples with the high number of polymorphic sites that they are able to detect.

The aim of this study was to assess the suitability of AFLP and SAMPL markers for determining the genetic variability between sheep breeds. Such a preliminary work is intended to understand whether these techniques could be used to differentiate breeds with a similar morphology.

The work was carried out on 62 individuals evenly distributed between three morphologically different breeds: Appenninica, Massese, and Suffolk.

AFLP and SAMPL techniques were performed according to Vos et al. (1995) and Morgante et al. (1994) and with 4 primer combinations each. The scoring of the resulting gels was carried out on a presence/absence basis for each band and the results analysed with the software SAS (SAS Institute Inc., 1989) using the discriminant procedures with a non-parametric method.

The four primer combinations used in the AFLP experiments detected 182 polymorphic bands, while the SAMPL experiments yielded 72 polymorphic bands. Although no breed-specific bands were identified the statistical analysis showed that even with such a limited number of primer combinations, it is possible to differentiate the three breeds and reassign individuals to the right group with a probability of 100%. This was true for both AFLP and SAMPL markers.

It is the first time that SAMPL markers are used in domestic animals and the first time that this statistical approach is used to analyse the results obtained from AFLP and SAMPL experiments.

The results are encouraging for the prospect of using the same approach to distinguish between morphologically similar individuals. Further primer combinations are being tested at present and a multivariate cluster analysis will be performed to assess the genetic distance that can be inferred from the obtained data.