Microsatellite and AFLP markers in the Prunus persica [L. (Batsch)]xP. ferganensis BC(1)linkage map: saturation and coverage improvement.

A set of 146 single sequence repeats (SSRs) and 14 amplified fragment length polymorphism (AFLP) primer combinations were used to enrich a previously developed linkage map obtained from a (Prunus persicaxP. ferganensis)xP. persica BC(1) progeny. Forty-one SSR primer pairs gave polymorphic patterns detecting 42 loci. The restriction/selective primer AFLP combinations produced a total of 79 segregating fragments. The resulting map is composed of 216 loci covering 665 cM with an average distance of 3.1 cM. Novel regions were covered by the newly mapped loci for a total of 159 cM. Eight linkage groups were assembled instead of the earlier 10 as two small groups (G1a and G8b), previously independent, were joined to their respective major groups (G1b and G8a). Several gaps were also reduced resulting in an improved saturation of the map. Twelve gaps >or=10 cm are still present. A comparative analysis against the Prunus reference map (71 anchor loci) pointed out an almost complete synteny and colinearity. Six loci were not syntenic and only two were not colinear. Genetic distances were significantly longer in our map than in the reference one.

Microsatellite markers isolated in olive ( Olea europaea L.) are suitable for individual fingerprinting and reveal polymorphism within ancient cultivars.

We have isolated and sequenced 52 microsatellites or simple sequence repeats (SSRs) from nearly 60 positive clones obtained from two 'Frantoio' olive genomic libraries enriched in (AC/GT) and (AG/CT) repeats, respectively. The repeat-containing fragments obtained from genomic DNA restricted with Tsp509I were separated using a biotinylated probe bound to streptavidin-coated paramagnetic beads. Fragments were then cloned into lambda ZAPII vector and sequenced. Thirty of the 36 primer pairs which gave correct re-amplification in the source genome were used to assay the polymorphism of 12 olive cultivars, namely four well-known cultivars ('Coratina', 'Frantoio', 'Leccino', 'Pendolino') and eight ancient cultivars grown locally near Lake Garda ('Casaliva', 'Favarol', 'Fort', 'Grignan', 'Less', 'Raza', 'Rossanel', 'Trep'). The local cultivars were each re- presented by two to four long-lived individuals. The analysis was carried out using (33)P-labelled primers and 6% polyacrylamide sequencing gels. All except two microsatellites showed polymorphism, the number of alleles varying from 1 to 5. The average genetic diversity ( H) was 0.55. The power of discrimination ( PD) was 0.60. All cultivars, including the local ones, were easily separated from each other. Variations in the SSR pattern were observed among individual plants of the same cultivar in four out of the eight local cultivars analysed. Several primer pairs (17%) amplified more than one locus.