INDUCTION AND CHARACTERIZATION OF EMBRYOGENIC CALLUS TYPES FOR THE INITIATION OF SUSPENSION-CULTURES OF LEEK (ALLIUM-AMPELOPRASUM L)

In this paper the development and characterization of a friable, embryogenic callus culture of leek is described. This callus type was initiated on immature embryos and differed in appearance from formerly induced compact, embryogenic callus [4]. The friable callus was comprised of numerous globular embryoids, embedded in a mucilaginous substance. The genotype of the donor plant and the embryo size were important parameters in the initiation of this callus type. Embryos of 0.5-2.5 mm gave the highest frequency of friable callus production. The basal media and inclusion of L-proline into the media did not influence the friable callus production. Light microscopic comparison of compact and friable callus showed striking differences. Compact callus consisted of a meristematic zone and contained vascular elements. Friable callus was less differentiated and contained aggregates of embryogenic cells, separated by intercellular spaces, and somatic embryos. Ten independently induced friable callus cultures were tested for their amenability to form suspension cultures. From one of these, two highly embryogenic suspension cultures were selected.