Publication Date

1989

Description

Interspecific hybridization has frequently been used in crop improvement programs to introgress economic traits from wild species into the cultivated germplasm pool. In alfalfa (Medicago sativa) unadapted accessions have been important sources of disease resistance and winterhardiness. However, unadapted germplasm sources used in alfalfa improvement to date have been limited to the M. sativa complex (McCoy and Bingham, 1988) A number of valuable traits have been ident­ified in other Medicago species (summarized in McCoy, 1985) but the obstacle to using other species had been the inability to recover interspecific hybrids.

Recently, the limits of crossability in the genus Medicago were significantly expanded by the development of an ovule­embryo culture technique (McCoy and Smith, 1986). Using this technique, it is now possible to hybridize alfalfa with all other species of the subgenus Medicago (McCoy and Bingham, 1988), with the exception of M. arborea. Several of the species have useful traits including Verticillium wilt and spring black­stem resistance in M. dzhawakhetica and salt tolerance in M. marina. Research is in progress to attempt to transfer the resist­ance gene(s) from the wild species into alfalfa.

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Potential Uses of Embryo Culture Derived Interspecific Hybrids of Alfalfa (Medicago sativa L.)

Interspecific hybridization has frequently been used in crop improvement programs to introgress economic traits from wild species into the cultivated germplasm pool. In alfalfa (Medicago sativa) unadapted accessions have been important sources of disease resistance and winterhardiness. However, unadapted germplasm sources used in alfalfa improvement to date have been limited to the M. sativa complex (McCoy and Bingham, 1988) A number of valuable traits have been ident­ified in other Medicago species (summarized in McCoy, 1985) but the obstacle to using other species had been the inability to recover interspecific hybrids.

Recently, the limits of crossability in the genus Medicago were significantly expanded by the development of an ovule­embryo culture technique (McCoy and Smith, 1986). Using this technique, it is now possible to hybridize alfalfa with all other species of the subgenus Medicago (McCoy and Bingham, 1988), with the exception of M. arborea. Several of the species have useful traits including Verticillium wilt and spring black­stem resistance in M. dzhawakhetica and salt tolerance in M. marina. Research is in progress to attempt to transfer the resist­ance gene(s) from the wild species into alfalfa.