Somatic embryogenesis
[2] Somatic embryos are mainly produced in vitro and for laboratory purposes, using either solid or liquid nutrient media which contain plant growth regulators (PGR’s).
[3] Shoots and roots are monopolar while somatic embryos are bipolar, allowing them to form a whole plant without culturing on multiple media types.
Somatic embryogenesis has served as a model to understand the physiological and biochemical events that occur during plant developmental processes as well as a component to biotechnological advancement.
[4] The first documentation of somatic embryogenesis was by Steward et al. in 1958 and Reinert in 1959 with carrot cell suspension cultures.
Initiation and proliferation occur on a medium rich in auxin, which induces differentiation of localized meristematic cells.
Applications of this process include: clonal propagation of genetically uniform plant material; elimination of viruses; provision of source tissue for genetic transformation; generation of whole plants from single cells called protoplasts; development of synthetic seed technology.
[1] The development of somatic embryogenesis procedures has given rise to research on seed storage proteins (SSPs) of woody plants for tree species of commercial importance, i.e., mainly gymnosperms, including white spruce.
[13][14] Grossnickle et al. (1992)[15] compared interior spruce seedlings with emblings during nursery development and through a stock quality assessment program immediately before field outplanting.
Growth and survival of interior spruce 313B Styroblock seedlings and emblings after outplanting on a reforestation site were determined by Grossnickle and Major (1992).
Response surface models of current-year needles net photosynthesis (Pn) response to vapour pressure deficit (VPD) and photosynthetically active radiation (PAR) showed that emblings had 15% greater Pn at VPD of less than 3.0 kPa and PAR greater than 1000 μmol m−2s−1.
Understanding the formation of a somatic embryo through establishment of morphological and molecular markers is important for construction of a fate map.
[17] Time-lapse tracking by Toonen et al. (1994) showed that morphology of competent cells can vary based on shape and cytoplasm density.
They developed into symmetrical, asymmetrical, and aberrantly-shaped cell clusters that eventually formed embryos at different frequencies.
Gradual removal of auxin and cytokinin and introduction of abscisic acid (ABA) will allow an embryo to form.
[17] Using somatic embryogenesis has been considered for mass production of vegetatively propagated conifer clones and cryopreservation of germplasm.
