Somatic Embryogenesis in Carrot (Daucus carota)

Abstract

The culture of carrot cells in liquid suspension dates from 1953 and the recognition of their totipotency from 1956 [10]. By 1962 it was feasible to maintain in the laboratory, routinely, liquid cultures, heterogeneous as to their unit size, but in which large numbers of embryos readily developed from suspended cell clusters and single cells [8]. By this time, the role of synergistic combinations of the growth-promoting complex as it occurs in coconut water with auxins such as naphthaleneacetic acid (NAA) and 2,4-dichloro-phenoxyacetic acid (2,4-D) had become well-known [11, 23]. Moreover, the advantages to be gained in some otherwise morphogenetically recalcitrant cell cultures, of sequential treatments with different growth-promoting complexes and systems, became appreciated [23]. By these general means it was shown that a number of umbelliferous plants (family Apiaceae) and species or cultivars from other families, could yield cells and somatic embryos which in turn could give rise to whole plants. But when the main sequence of embryogenic development of carrot cells became known [24], it was found that its outcome could be greatly altered by the environmental conditions and the identity and mode of application of the growth and morphogenetic stimuli [11, 23].