Genomic DNA fingerprints as a tool for identifying cultivated types of radicchio (Cichorium intybus L.) from Veneto, Italy

Red or variegated chicory (Cichorium intybus L., 2n = 2x = 18) native to, and very extensively cultivated in north-eastern Italy as a leafy vegetable, locally called 'radicchio', includes different types which represent valuable high-quality crops. The five major types of radicchio cultivated in the Veneto region were investigated by polymerase chain reaction (PCR)-derived markers. The experimental material was represented by two outbred populations (one of 'Variegato di Castelfranco' (CF) and one of 'Rosso di Verona' (VR)) and by eight inbred lines (three of early 'Rosso di Treviso' (TVP), three of late 'Rosso di Treviso' (TVT) and two of 'Rosso di Chioggia' (CH)). A total of 96 individual plant DNAs and 16 bulked DNAs of six plants each were assayed. The different types were well distinguished from one another if analysed by means of bulks using amplified fragment length polymorphism markers at the population level, while they were not if analysed at the individual level using random amplified polymorphic DNA, inter-simple sequence repeat and Arbitrarily Primed (AP)-PCR markers. The genetic variation was shown to be much higher within types than between types. This result suggests that, in each radicchio type, populations produced by breeders through controlled intercrossing (VR and CF) or repeated selfing (TVP, TVT and CH) conserved their well-separated gene pools over the years. The setting up of a molecular reference system seems to be feasible and suitable both for the precise identification of the single types of radicchio and for the evaluation of the extent of natural hybridization that can occur between different types.