Somatic Hybrids of the Forage Legumes Medicago sativa L. and M. falcata L.

Protoplasts isolated from embryogenic cell suspensions of tetraploidMedicago sativa cv. Europe (2n= 4? = 32) and M. falcata (2n=4? = 32) were fused using polyethylene glycol (PEG). Heterokaryonswere isolated by micromanipulation and cultured in the presenceof nurse protoplasts from albino or embryogenic cell suspensionsof M. sativa, to give free-floating embryos and embryogeniccalli. Ninety-nine plants were regenerated from somatic embryos.Fifteen of the plants exhibited leaf abnormalities and did notsurvive transfer from culture to the glasshouse. The remainingphenotypically normal plants were established ex vitro and floweredat maturity. Morphological and biochemical analyses confirmedthat 12 of the phenotypically normal plants were somatic hybrids.Morphological characteristics of the hybrids, including plantstature, internode length, leaf size, flower colour, and podshape, were intermediate compared with those of the purple floweredM. sativa and yellow flowered M. falcata parents. Flowers ofthe hybrids were yellow traced with purple-blue veins. Isoenzymebanding patterns for esterase showed bands additional to thoseof M. sativa and M. falcata. The chromosome complements of individualhybrids varied from (2n= 4? = 32) to 58.