Effect of farmers’ seed selection on genetic variation of a landrace population of Pepper (Capsicum annuum L.), grown in north-west Italy

Recognition by the European Community of élite landraces encourages farmers to grow these and earn more than is possible by growing modern varieties. However, farmers often exercise strong selection by collecting seed from a limited number of plants which best embody a few characters of prime interest. This, in the long run, may be responsible for considerable genetic erosion. In Southern Piedmont, North-West Italy, a local landrace of pepper (Capsicum annuum L.) known as Cuneo is grown; it deserves particular attention because of its hardiness, late production and fruit quality. We used random amplified polymorphic DNA (RAPD) and amplified fragment length polymorphism (AFLP) markers to assess the effect, on genetic composition of a population, of seed sampling carried out using the selection criteria adopted by the farmer. After two reproductive cycles using selection, it was already possible to detect loss in genetic variation and a change in allele frequencies, while no significant effect was found after two cycles of random sampling. Over this period, farmer selection pressure led to disappearance of eight low-frequency alleles, while only three alleles were lost in randomly sampled populations. Our results stress the need to adopt appropriate techniques for seed sampling in order to avoid genetic erosion of local landrace gene pools.