Submit Article |Resources | Link to us | Sitemap | Search | Language
Back to Home
Home >> Organogenesis and Embryogenesis >>Practical Applications of Somatic Embryogenesis
Back to Home

Practical Applications of Somatic Embryogenesis -

There are many practical applications of somatic embryogenesis. It has a potential application in plant improvement.

Since both the growth of embryogenic cells and subsequent development of somatic embryos can be carried out in a liquid medium, it is possible to combine somatic embryogenesis with engineering technology to create large scale mechanized or automated culture systems.

Such systems are capable of producing propagules (somatic embryos) repetitively with low labor inputs. In this process of repetitive somatic embryogenesis (also referred to as accessory, adventive, or secondary somatic embryogenesis) a cycle is initiated whereby somatic embryos proliferate from the previously existing somatic embryo in order to produce clones.

Embryos formed directly from preembryogenic determined cells appear to produce relatively uniform clonal material, whereas the indirect pathway involving induced emsomaclonal variantsbryogenic determined cells generates a high frequency of .

Mutation during adventive embryogenesis may give rise to a mutant embryo which on germination would form a new strain of plant. Nucellar embryos, such as shoot tips, are free of virus and can be used for raising virus free clones.

Clonal propagation through somatic embryogenesis has been reported in 60 species of woody trees representing 25 families. There is considerable worldwide interest in the development of methods for encapsulation of somatic embryos to enable them to be sown under field conditions as "synthetic" or "artificial" seeds.

Artificial seeds, consisting of somatic embryos enclosed in a protective coating, have been proposed as a "low cost high-volume" propagation system. The inherent advantages of artificial seeds are the production of many somatic embryos and the use of conventional seed handling techniques for embryo delivery.

The objective is to produce clonal "seeds" at a cost comparable to true seeds. Two types of artificial seeds have been developed, namely, hydrated and desiccated. Redenbergh et al. (1986) developed hydrated artificial seeds by mixing somatic embryos of alfalfa, celery, and cauliflower with sodium alginate, followed by dropping into a solution of calcium chloride to form calcium alginate beads.

About 29-55% embryos encapsulated with this hydrogel germinated and formed seedlings in vitro. Kim and Janick (1989) applied synthetic seed coats to clumps of carrot somatic embryos to develop desiccated artificial seeds.

They mixed equal volumes of embryo suspension and 5% solution of polyethylene oxide (poly ox WSR N-750), a water soluble resin, which subsequently dried to form polyembryonic desiccated wafers.

The survival of encapsulated embryos was further achieved by embryo "hardening" treatment with 12% sucrose or 10-6 MABA, followed by chilling at high inoculum density.

Another delivery system for somatic embryos for obtain­ing transgenic plants is fluid drilling. Embryos are suspended in a viscous carrier gel which extrudes into the solid.

The primary problem in fluid drilling is that the sucrose level necessary to permit conversion also promotes rapid growth of contaminating microorganisms in a non aseptic system.

Embryogenic callus, suspension cultures and somatic embryos have been employed as sources of protoplast isolation for a range of species. Cells or tissues in these systems have demonstrated the potential to regenerate in cultures and thereby yield protoplasts capable of forming whole plants.

Somatic embryos give rise to genetically uniform plants. The advent of leaf disk transformation systems has made it possible to successfully engineer species in which tissues are capable of regeneration via somatic embryogenesis.

Isolated single cells can be transformed in cultures and grown on a selection medium (nutrient medium containing an antibiotic, kanamycin) to callus colonies which eventually form somatic embryos on removal of auxin from this medium. The callus phase can be bypassed through a process of repetitive somatic embryogenesis.

Since repetitive embryos originate from a single epidermal or subepidermal cell, they can be exposed to the Agrobacterium transformation technique. Thus a primary somatic embryo will give rise to totally transgenic somatic embryos. Repetitive embryogenesis is also ideally suited to particle gun mediated genetic transformation.

Instead of relying on Agrobacterium to mediate the transfer of genes into plant cells, the particle gun shoots DNA that has been precipitated of particles of a heavy metal into the plant cells. The repetitive embryogenesis system is of potential use in the synthesis of metabolites such as pharmaceuticals and oils.

  • Embryogenesis
  • Practical Applications of Somatic Embryogenesis
Submit Article |Resources | Link to us | Sitemap | Search | Language
English|Français|Español|Deutsch|Italiano|Portugues|Japanese|Korean|Sim-Chinese| Language