Embryogenesis auxin

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. 

Fig. 2. Somatic embryogenesis in Hinoki cypress. A Collected open-pollinated cones. B Proliferation of induced embiyogenic tissue on medium containing auxin and cytokinin. C Embryogenic cells. D-F Different developmental maturation stages of somatic embryos. G Production of somatic embryos. H Germination of somatic embryos. I Plantlets growing in vitro. J Acclimatized plants derived from somatic embryos. K-L Somatic plants growing out in the field. Bars 1mm (C-F), 1cm (A-B, G-J), Im (K-L)...

The polar transport of auxin in early globular embryos is essential for the establishment of bilateral symmetry during plant embryogenesis. Interference with this transport causes a failure in the transition from axial to bilateral symmetry and results in the formation of embryos with fused cotyledons (Liu et at, 1993). 

Brown CL, Wodzicki TJ (1969) A simple technique for investigating cambial activity and differentiation of cambial derivatives. For Sci 15 26-29 Child CM (1941) Patterns and problems of development. Univ Chicago Press, Chicago Crick FHC (1970) Diffusion in embryogenesis. Nature 225 420-422 Crick FHC (1971) The scale of pattern formation. In Davies DD, Balls M (eds) Control mechanisms of growth and differentiation. Symp Soc Exp Biol 25 429 38 de la Fuente RK, Leopold AC (1966) Kinetics of polar auxin transport. Plant Physiol 41 1481-1484... 

Auxins are well-known plant growth hormones involved in plant processes including embryogenesis, apical patterning, stem elongation, development of vascular tissues, and root initiations that mediate gravitropic and phototropic responses in... 

---