Phaseolus genetic diversity maintained on farm in Central Italy.

Thirty-one Phaseolus vulgaris (L.) and five Phaseolus coccineus (L.) landraces reproduced on-farm were found in central Italy. They were mostly grown by elderly farmers who usually select for a certain type of seed. Different varieties are often grown in each location and on each farm. They are maintained on-farm because of a local market request for high quality products or because of sticking to traditional family use in cooking (21.2 and 75.8% of recorded cases, respectively). Three AFLP primer combinations were used to assess genetic variation among collected materials, a wild accession of P. vulgaris and commercial varieties of both species. They revealed a quite high percentage of polymorphism (90.2% of polymorphic bands as an average). A wide genetic variation was observed among collected materials and each accession showed a unique pattern of polymorphism. Within P. vulgaris, landraces were discriminated in two main subgroups, the former including the accessions from the Mediterranean area around the Lake Trasimeno and the latter including accessions from the humid Mediterranean area within the Appennine Mountains. These findings demonstrate the peculiar genetic identity of the landraces studied also in relationship to human and environmental selection pressures. Possible on-farm conservation strategies are briefly discussed in relationship to the information collected.