79 RAPD and AFLP Analysis for Olive Mapping R. De la Rosa, A. Martin and L. Rallo Dpto. Agronomia - Universidad de Córdoba, Córdoba, Spain A. Angiolillo, C. Guerrero and L. Baldoni Istituto di Ricerche sulla Olivicoltura - C.N.R., Perugia, Italy Keywords: Genome mapping, AFLP, RAPD, Olea europaea. Abstract Poor information is available on the genetic control of the agronomic traits under selection in olive, but the use of linked markers would permit an early selection of the progenies by the Marker-Assisted Selection (MAS), particularly important for traits related to the mature phase, such as productivity, fruit size and oil quality. We present here the progress on establishing a genetic linkage map for olive using an F1 as segregating population obtained by intervarietal cross between two highly heterozygous cultivars, 'Leccino' and 'Dolce Agogia'. AFLPs and RAPDs were used as dominant markers to locate suitable markers in the map. Only markers heterozygous in one parent and homozygous recessive in the other were useful to produce a map for each parental line. For this reason only bands present in one parent and absent in the other, segregating 1:1 in the F1 progeny, were scored. Data were processed with a PC version of MAPMAKER/EXP 3.0 (Lincoln et al. 1993). For each marker the reversed genotype was also considered because their phase in the gametes was unknown. Linkage values with the highest LOD scores were adopted. A total of 166 AFLP markers were obtained from 15 different primer combinations. 85 markers were scored as heterozygous in 'Dolce Agogia', 81 in 'Leccino'. As far as RAPDs are concerned, 62 primers gave a total of 275 polymorphisms, 151 in 'Leccino' and 124 in 'Dolce Agogia'. 22 linkage groups were obtained for 'Leccino' and 23 for 'Dolce Agogia' with 179 and 167 markers linked respectively. An allele of the Stearoyl-ACP Desaturase gene, involved in the formation of oleic fatty acid in olive oil and previously identified in olive (Baldoni et al., 1996), was located on a linkage group of 'Leccino'. INTRODUCTION Olive is a diploid species (2n=46) with a very long generation time, which makes the availability of F2 or backcross progenies difficult to use as segregating populations. Most of the olive cultivars have unknown origin. First breeding programs are currently in progress but the very long juvenile phase seriously affects the evaluation, selection and release of new genotypes. This obstacle was greatly reduced by the development of protocols that forced the seedling growth (Santos-Antunes et al., 1999), but even using this system it is necessary to wait at least four years to have a good agronomic characterisation of the plants. The molecular markers recently developed in other fruit tree species (Janick, 1996) appear very promising to permit an early selection of the breeding progenies. This early selection is based on the linkage of traits controlling aspects of agronomic interest with molecular markers that can be tested in a very early phase of the seedling growth. To establish this type of association it is necessary to develop a linkage map, as is currently done in other important fruit crops like apple (Maliepaard et. al, 1999) and Prunus species (Arus et al., 1994). The present work represents a first step to develop a genomic linkage map for the olive species. MATERIALS AND METHODS A progeny of 100 seedlings obtained by the cross between two highly heterozygous cultivars, 'Leccino' and 'Dolce Agogia', was selected as segregating population for map construction. Proc. 4 th IS on Olive Growing Eds. C. Vitagliano & G.P. Martelli Acta Hort. 586, ISHS 2002