Abstract

Medicago polymorpha is a naturalized species in Chile which presents great variability in agronomic traits such as flowering and reproductive phenology, seed production, seed hardness, and dry matter production, associated to a climatic gradient. The objectives of this work were to assess the isozymatic diversity in accessions of M. polymorpha and its relation with the phenotypic variability, and to establish possible genetic links with other species of Medicago. Forty one accessions of M. polymorpha obtained from a wide range of climatic and edaphic conditions, and 16 accessions of M. arabica, M. rotata, M. rigidula, M. tornata, M. littoralis and M. truncatula, were evaluated for 12 isozyme systems. The results showed a low isozymatic diversity within accessions of M. polymorpha, and a lack of association between geographical distribution and isozyme diversity. Multivariate analysis allowed to cluster the species separately. M. arabica, another naturalized species in Chile, was the closest species to M. polymorpha, whereas M. littoralis, M. rigidula and M. rotata presented a higher genetic distance from M. polymorpha.