Isozymatic diversity in accesions of Medicago polymorpha collected along an environmental gradient in Chile, and its relationship with other species of Medicago

Medicago polymorpha is a naturalized species in Chile which presents great variability in agronomic traits such as flowering and reproductive phenolog y, seed production, seed hardness, and dry matter production, associated to a climatic gradient. The objectives of this work were to assess the isozym atic diversity in accessions of M. polymorpha and its relation with the phe notypic variability, and to establish possible genetic links with other spe cies of Medicago. Forty one accessions of M. polymorpha obtained from a wid e 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 dive rsity within accessions of M. polymorpha, and a lack of association between geographical distribution and isozyme diversity. Multivariate analysis all owed to cluster the species separately. M. arabica, another naturalized spe cies in Chile, was the closest species to M. polymorpha, whereas M. littora lis, M. rigidula and M. rotata presented a higher genetic distance from M. polymorpha.