Morphological and genetic diversity among and within common bean (Phaseolus vulgaris L.) landraces from the Campania region (Southern Italy)

• We analyzed 26 qualitative and 11 quantitative traits in 25 common bean landraces cultivated in Southern Italy.
• We examined patterns of genetic polymorphism, differentiation and population structure using 10 SSR loci.
• A wide-ranging morphological and molecular variation among and within cultivated landraces was observed.
• Our work provided evidence to support measures for landraces’ on-farm conservation.

The common bean (Phaseolus vulgaris L.) is arguably the most important food legume and a fundamental source of proteins especially for rural societies. In several countries, this species is characterized by a number of locally adapted landraces and many of them are at risk of extinction. In Italy, common bean cultivation has always been a typical element of rural economies especially in the Southern regions. We carried out an investigation of the morphological and genetic diversity in 25 common bean populations cultivated in the Campania region (Southern Italy). We analyzed 26 qualitative and 11 quantitative traits following the IPGRI descriptors. Furthermore, 10 SSRs were employed to examine genetic polymorphism, differentiation and population structure. Molecular and morphological data distinguished all the landraces under investigation. A considerable phenotypic diversity among landraces was observed for many characters, including some related to agronomical performance. At molecular level, all the SSRs were polymorphic, with an average of 8.5 alleles per locus. Moreover, the vast majority of the landraces (92%) displayed intra-varietal differences. Our work indicated the presence of a wide-ranging variation among and within cultivated common bean landraces. Moreover, it provided evidence that the implementation of measures for their on-farm conservation, management and promotion should be useful also to preserve genetic variability.