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, embry ogenic callus culture of leek is described. This callus type was initi ated on immature embryos and differed in appearance from formerly indu ced 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 par ameters in the initiation of this callus type. Embryos of 0.5-2.5 mm g ave the highest frequency of friable callus production. The basal medi a and inclusion of L-proline into the media did not influence the fria ble callus production. Light microscopic comparison of compact and fri able 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, se parated by intercellular spaces, and somatic embryos. Ten independentl y induced friable callus cultures were tested for their amenability to form suspension cultures. From one of these, two highly embryogenic s uspension cultures were selected.