Molecular characterization of the autochthonous grape cultivars of the region Friuli Venezia Giulia – North-Eastern Italy

A sample of 48 accessions belonging to important autochthonous grapevine varieties from Friuli Venezia Giulia (North-Eastern Italy) was analyzed using two sets of microsatellite markers. One marker set, based on di-nucleotide core repeats, was compared with a recently developed set of markers based on tri-, tetra-, and penta-nucleotide repeats in order to determine genetic identities, estimate genetic diversity, and establish the power of discrimination of the two sets. A total of 20 di-nucleotide SSR markers and 19 tri-, tetra-, and penta-nucleotide SSR markers were used to screen the accessions.All 39 primers produced PCR amplicons that were polymorphic and easily scorable in all of the accessions studied. Both datasets allowed the discrimination of all cultivars but two ('Refosco di Runcis' and 'Refoscone'). The observed heterozygosity ranged from 0.21 to 1.0 for the di-nucleotide markers, and from 0.21 to 0.88 for the tri-, tetra-, and penta-nucleotide repeat motif microsatellites, respectively.The population structure of the 48 autochthonous accessions was evaluated, together with 8 international cultivars included as references, providing evidence for significant population structure within the sample. Microsatellites composed of tri-, tetra-, and penta-nucleotide repeats, characterized by low ‘stuttering’ and larger relative size differences between incremental alleles, are now available for grape fingerprinting.

Characterisation of the grapevine cultivar Picolit by means of morphological descriptors and molecular markers

The phenotypic and genotypic variability of cv. Picolit, an ancient, female-flower cultivar from north-eastern Italy was investigated by means of ampelographic and ampelometric descriptors and by molecular markers, such as microsatellites and AFLPs. Thirty nine samples were collected from old plants (30-100 years old), which showed some differences in morphology and growth. In two samples (P6 and P7) morphological differences were found. These samples showed a different allelic profile at 18 out of the 21 SSRs analysed and were therefore considered not to belong to the cv. Picolit. Of the remaining samples, 35 gave the same allelic pattern at all SSRs and they were therefore considered ‘true-to-type’ Picolit, whereas two of them (P4 and P8) showed several variations, including extra alleles. One of the possible causes of such differences is chimerism. The AFLP analysis, from which samples P6 and P7 were excluded, enabled screening of a larger portion of the genome and confirmed the differences of the P4 and P8 samples from the remaining ones. P4 and P8 were different from the majority of samples at 13 and 37 AFLP loci respectively. A few further polymorphic bands were recorded in the remaining samples, but they were disregarded since they were not always reproducible. This research confirmed the appreciable somatic stability of SSR markers even in long-lived, vegetatively propagated plants, and the occasional occurrence of solid mutations and chimerisms.

Genotyping wine and table grape cultivars from Apulia (Southern Italy) using microsatellite markers

Thirty-eight typical grapevine varieties of the Apulia region, Southern Italy, were genotyped at 6 microsatellite loci (VVS2, VVMD5, VVMD7, VrZAG47, VrZAG62, VrZAG79) with the aim to find synonymy and to confirm some pedigrees reported in literature. Microsatellites were amplified by PCR with 33P-ATP labelled primers and alleles separated by electrophoresis using 6 % acrylamide sequencing gels. The results confirm the high information level of the selected microsatellites. The number of alleles ranged from 7 to 11, producing up to 23 different combination patterns. The observed heterozygosity varied between 81.6 and 94.7 %, the discrimination power between 0.888 and 0.939, and the probability of identity was as low as 0.06-0.12. All cultivars of the study were discriminated from each other, except Regina (syn. Afuz Ali) and Mennavacca, which had the same profile. Finally, we were able to confirm the parentage of Victoria (Cardinal x Afuz Ali) and Matilde (Italia x Cardinal).