Somatic seeds

Research Problems Associated with Somatic Seeds... 

Finally, since somatic embryos are naked, it is presently envisioned that they will need to be coated with a protective covering analoguous to the seed coat of zygotic seeds. The combined covering and somatic embryo is referred to as a somatic seed (Figure... 

Figure 2. Critical research problems for production of somatic seeds.

Figure 3. Somatic seeds. Alfalfa somatic embryos encapsulated in calcium alginate beads. Each capsule is approximately 4 mm in diameter.

Finally, germination of the somatic seeds and conversion to complete, vigorous plants is essential. To date, research has focused on in vitro conversion experiments with celery and alfalfa. For both crops, the conversion frequencies for somatic seeds is identical to that for naked somatic embryos. For celery, this is 60-90% while alfalfa conversion is 40-50%. Although the frequencies vary from experiment to experiment, within any one experiment, somatic seeds and naked embryos show the same response. 

Cook DA, Brown A III. Somatic embryogenesis and organogenesis in okra (Abel-moschus esculentus L. Moench.) Somatic Embryogenesis and Synthetic Seed 1995 31 164-169. 

Synthetic seed is an alternative to TPS that would avoid the need to develop parents that generate uniform hybrids. Hence there is currently renewed interest in somatic embryogenesis in potato, and sufficient progress has been made for serious consideration to be given to exploiting S5mthetic potato seed, as seen in the review by Veilleux (2005). 

Embryo cultures may be established from embryos removed from sterilized seeds, ovules, or fruits. The embryos produced from cell culture technique, known as somatic embryos, can be isolated and germinated to provide one plant per explant. Embryo culture can be employed for the rapid production of seedlings from seeds which have a protracted dormancy period. The method has many potential advantages over traditional propagation systems, such as fast turnaround, genetic uniformity, mass production, and propagation of disease-free plants. 

Arenas, P., and B.K. Vig. Somatic crossing-over in Glycine max (L.) merrill Activation of dimethyl nitrosoamine by plant seed and comparison with methyl nitrosourea in inducing somatic mosaicism. 

To further confuse the issue, despite the higher concentration of alkaloids in the Woodrose seeds, the trip is generally experienced by Westerners as both somatically unpleasant and not particularly psychedelic. In glaring contrast, Mexican shamans routinely ingest (to us) subthreshold doses of a much less potent species to encounter full-blown allies from the imaginal realm who aid them in their diagnoses. What accounts for the discrepancy ... 

DPA-GS is a major metabolite of ABA in, among others, soybean seeds [96], tomato plants [97], and sunflower embryos [98]. Suspension cultures of maize cells [99] and of somatic embryos of white spruce [100] convert ABA almost quantitatively to PA. ABA-GS is present in tomato plants [101]. 

Improvement in taste or texture of vegetables and fruits, such as better tasting celery stalks and tomatoes with higher solids content (13). Somaclonal variations for selection of desirable variants, and somatic embryos (artificial seeds) have been especially useful in genetic engineering of improved vegetables. Several of these new crop varieties will be on the market within 2 to 4 years. 

Because they are biochemically similar to zygotic embryos (3,4), somatic embryos also present an opportunity for vitro production of numerous secondary plant products which are associated with seeds. For example, essential oil, flavor, and aroma components found in seeds of celery (5), cocoa (6,7), and oil palm (8) are produced by somatic embryos. The ability to control and develop this process may permit more economical and reliable production of certain plant products on an industrial level. 

Low 2,4-D treated embryos accumulated 2.4 ug each of the IIS protein found in alfalfa seed, while the 50 uM-treated embryos accumulated less than 20 ng each (Figure 4). This result indicates that the level of storage protein accumulation is related to normalization of embryo development and may represent a useful assay to assess somatic embryo quality (4). The maxiumum level of protein accumulation is less than 107o of the level expected for alfalfa seed, however, suggesting that there is additional room for improvement in somatic embryo quality. 

Figure 4. Alfalfa somatic embryo proteins separated after extraction by sucrose density gradient separation (left side of chromatogram) and SDS-polyacrylamide electrophoresis (right side of chromatogram). The 2,4-D-treated embryos express more IIS protein as shown in the sucrose gradient. The IIS protein has polypeptides that co-migrate with IIS seed protein as shown by SDS-PAGE. (Reproduced with permission from reference 4. Copyright 1985, Plenum Publishing.)...

There has been no further report on these plants. In any case, the somatic hybrid lines could not be commercially utilized even if they were fertile. Crosses using a potato line as a recurrent pollen parent do not result in an alloplasmlc substitution form of the pollen parent, because potato cultivars cannot be maintained by seed due to their heterozygosity. 

Figure 9.6 Illustration of genes expressed with similar patterns in cluster set 11 of the microarray data of somatic cmbryogcncsis. Adapted from I hibaud-Nisscn et al The annotations matching clone IDs on the microairay sets represent the top Blastx hit in the public databases at a threshold of H -6. The putative function in cell metabolism is shown cgm, cell growthm and maintenance cn, energy sig, signaling sp, seed protein to, transcription u, unknown.

Dose-dependent induction of chromosomal aberrations and sister chromatid exchanges were observed in human lymphocytes treated with dill leaf or seed essential oil. No significant effects of dill seed essential oil were observed in the Drosophila melanogaster somatic mutation and recombination test (SMART) in vivo (Lazutka et al. 2001). 

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