New Interspecific Hybrids in the Genus Medicago through In Vitro Culture of Fertilized Ovules

In the genus Medicago interspecific crosses are often prevented by post-zygotic mechanisms of incompatibility, that interfere with the development of the hybrid embryos (Oldemeyer, 1956; Fridricksson and Bolton, 1963; Sandguen et al., 1983; McCoy, 1985). As a consequence, germplasm sources available for alfalfa improvement are limited to the M. sativa complex, which includes the species M. falcata, M. media and M. glutinosa, that are freely crossable with M. sativa (Lesins and Lesins, 1979). Out of this group, conventional sexual cross between M. sativa and otherMedicago species has succeeded in only a few cases (Clement, 1963; Lesins, 1961a, 1961b, 1962, 1968, 1970, 1972; Lesins and Lesins, 1979; Sandguen et al., 1982).