Characterization by molecular markers of 'Pompia', a natural citrus hybrid cultivated in Sardinia

The 'Pompia' is a probable Citrus natural hybrid sporadically growing in the Baronia area (East Sardinia, Italy). The origin and taxonomic classification of this Citrus taxon is unknown. The fruit shows a yellow-amber flavedo at maturity and large size (weight from 200 to 700 g), irregular shape, light-yellow pulp, and low juice content. The traditional use as food is limited to the thick albedo after removal of the flavedo tissue and of the acid, non-edible pulp. This research had as its objective a characterization by molecular markers of nine accessions selected from four orchards of 'Pompia', in order to compare these genotypes with some Citrus species candidate to be the parents of this hybrid. AFLP, RAPD, and SCAR analysis allowed the comparison of 'Pompia' with six Citrus species: citron, lemon, 'Volkamer' lemon, pummelo, grapefruit, sour orange, and mandarin. The analysis with molecular markers demonstrated a close genetic relationship among 'Pompia', lemon, and citron. Overall, molecular analyses showed a high level of similarity of the nine 'Pompia' accessions. Seven of them probably genetically correspond to the same clone.