Rooting embryogenesis

There is compelling evidence for determination in the development of plants (6-10). During embryogenesis, root and shoot meristems arise from a common cell, the zygote. These structures consist of self-renewing populations of cells committed to form specific structures (11). This commitment is evident when small explants containing apical meristems are cultured in isolation. Explants from shoot tips form shoots in culture, whereas explants from root tips form roots in culture (12-15). 

Fig. 25.3 The pathways that can be taken in the development of plant tissue and cell cultures starting from a part of a plant (explant). The explant can via direct embryogenesis or oganogenesis form embryos or shoot and roots, respectively, which can be converted into plants. In another path, the explant can form a callus, which can then be used to form a suspension culture. In addition, indirect organogenesis or embryogenesis of the callus can lead to plant formation...

Figure 5. Alfalfa embryogenesis. A. An alfalfa somatic embryo, E, about to germinate, which is surrounded by callus C. B. Plantlets rooting. C. Regenerated plants in gravel in the greenhouse.

P, Kutchan T. Transformation of opium poppy with antisense 74. berberine bridge enzyme gene via somatic embryogenesis results in an altered ratio of alkaloids in latex but not in roots. Transgenic Res. 2004 13 607-613. 75. 

In nature, auxins are produced in apical and root meristems, young leaves, seeds and developing fruits, and their main functions are cell elonj tion and expansion, suppression of lateral buds, etc. (Opik RoUe, 2005). In somatic embryogenesis this is considered one of the most important elements producing cell polarity and asymmetrical cell division. In general, relatively high auxin concentrations (2,4-D, lAA, etc.) favor callus formation and the induction process (cell polarity). Afterwards, when the induction stage has been achieved, it is necessary to reduce or eliminate the auxins in order to initiate the bilateral symmetry and the expression of the somatic embryos. 

Dubois, T., Guedira, M., Dubois, J. Vasseur, J. (1990). Direct somatic embryogenesis in roots of Cichorium is caUose an early marker Annals of Botany, Vol. 65, No. 5, (May... 

In contrasted to the embryogenesis, organogenesis occurs via apparent shoot meristem or leaf primordial (Fig.2h-i). Histological analysis shows that non-embryogenic cells are large, and vacuolated parenchymal cells contain few plastids (Zhang et al., 2010). Callus will differentiate into adventitious shoots, and develop with subsequent formation of adventitious roots. 

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