Exploring molecular, morphological, and biochemical diversity of Phaeolus vulgaris landraces cultivated in the Aniene Valley (Lazio region, Italy)

The cultivation of common beans has long been integral to rural economies in Italy, particularly in mountainous regions along the Apennine ridge, where the production focuses on local landraces grown by smallholder farmers using low-input methodologies. However, recent socioeconomic changes in rural communities pose a threat of genetic erosion to these landraces. This study examines the genetic diversity, structure, and uniqueness of common bean landraces in the Aniene Valley of the Lazio region to develop preservation strategies. Seventy-three accessions were investigated using morphological (seed traits), biochemical (phaseolin and phytohemagglutinin patterns), and molecular (microsatellite loci) analyses. These analyses revealed significant genetic variability within morphologically uniform seed materials and highlighted cases of homonymy and the inadvertent introduction of foreign genetic material. Among the 292 samples analyzed (four per accession), a clear differentiation between Mesoamerican and Andean gene pools was observed, with the Andean pool being predominant. Despite high levels of homozygosity and uniform seed morphotypes, genetic variability was detected in sixteen of the twenty-one landraces, suggesting that analyzing only a single or few plants per landrace may yield incomplete genetic information. The extensive morphological, biochemical, and genetic characterization of the P. vulgaris collection from the Aniene Valley provides insights for planning effective conservation strategies. These findings emphasize the importance of both in situ/on-farm and ex-situ conservation to preserve the genetic diversity and heritage of these local landraces.