The Use of Single Somatic Embryo Culture in Propagating and Regenerating Lucerne (Medicago sativa L.)

Abstract

Embryogenic cultures of lucerne (Medicago sativa L.) cv. Robot have been established and propagated on medium containing yeast extract. These cultures consisted of unorganized callus tissue bearing embryogenic centres which increased in size during subculture, yielding new regenerated somatic embryos at the end of each 20-d subculture. A development in the propagation of the embryogenic cultures was the establishment of single embryo culture in hormone-free medium where, in selected cases, the process of recurrent somatic embryogenesis (RSE) took place on the hypocotyl of explanted embryos. The process was independent of supporting callus tissue and occurred on simple defined medium. Single embryos underwent either plantlet development or continued RSE on the hypocotyl. One third of the regenerated plantlets showed RSE after the two to three trifoliate leaf stage. In these cases shoot development stopped and only somatic embryo production took place. In vitro cloning of regenerated plantlets allowed us to reproduce each particular genotype before transplantation into soil.