SOMATIC EMBRYOGENESIS

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NAMA : ARYA WIRA WARDHANA

NPM : 21025010035

KELAS : A025

MATA KULIAH : BIOTEKNOLOGI

 

SOMATIC EMBRYOGENESIS


Somatic embryogenesis (SE) is the process by which somatic cells, under conditions suitable for induction, generate embryogenic cells, which go through a series of morphological and biochemical changes that result in the production of a bipolar structure without vascular connection with the original tissue (Solis Ramos et al.  2012 ). SE with a low frequency of chimeras, a high number of regenerants, and a limited level of somaclonal  variation is more attractive than organogenesis as a plant regeneration system (e.g., in genetic transformation, in vitro mutagenesis, and selection). Somatic embryos are formed from plant cells that are not normally involved in the develop-ment of (zygotic) embryos, i.e., ordinary plant tissue. No endosperm or seed coat is formed around a somatic embryo. 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, etc.


Somatic embryo  is an embryo formed in vitro from  somatic cells or embryogenic cells by mitotic cell division. “Mature somatic embryo,” however, is a fully developed embryo with evidence of root and shoot apices and exhibits a bipolar structure. Preferred mature somatic embryos are those with well-defi ned cotyledons. Rangaswamy ( 1986 )  and Ammirato ( 1989 ) have reviewed the phenomenon of somatic embryogenesis.


Development of somatic embryos directly from  intact explants (without an intervening callus phase) is known as primary direct somatic embryo-genesis (Ammirato  1989 ). According to Quiroz-Figueroa et al. ( 2006 ), somatic embryos originate by two pathways: (i) unicellular and (ii) multicellular. When somatic embryos have unicellular origin, cell division is seen to be coordinated, and the somatic embryo is sometimes connected to the maternal tissue by a  suspensor- like structure. In contrast, somatic embryos of multicellular origin are observable initially as a protuberance, showing no coordinated cell division, and those somatic embryos here that are in contact with the basal area are typically fused to the maternal tissue. Srinivasan and Mullins ( 1980) demonstrated SE from unfertilized ovules of seedless grapes, while Salunkhe et al. ( 1997 ) developed SE and subsequent plantlet formation from tendrils of grape plants. Carimi et al. ( 2005 ) could induce somatic embryogenesis in stigmas and styles of grapevine. Ontogenesis, differentiation, and precocious germination in anther- derived somatic embryos of grapevine through proembryogenesis have also been studied (Faure et al.  1996 )


A case study


Somatic embryogenesis is the most common regeneration system for grapevine ( Vitis   spp.)(Gribaudo et al.  2007 ). After rice, the second food crop to be fully sequenced genomically isthe grape (var. Pinot Noir). This is viticulture’s equivalent of the fi rst moonwalk. The geneticblueprint will make it possible to develop new, more resistant varieties (www.biotechweblog.com). Thus, grape is the fi rst fruit crop genome to be mapped. The far-reaching consequences of having sound regeneration systems in grape to plumb the wealth of genetic information, therefore, cannot be undermined. However, implementation of these strategies for grape improvement requires the ability to manipulate and achieve regeneration from cells and tissues in vitro. Somatic embryo-genesis being central to such manipulations encompasses culture initiation, maintenance, manipulation of somatic embryos, and plant development and, fi nally, incorporates specifi c uses of embryogenic culture systems. For perennial embryonic culture system (e.g., grape), several methods have proven effective for regeneration by somatic embryogenesis.


Method for producing Somatic Grape Embryos


The method includes the general steps of (a) providing a liquid culture comprising an embryogenic cell, (b) selection of embryogenic cell from the culture, (c) transferring the embryo-genic cell to a second culture, and (d) growing a somatic grape embryo from the embryogenic cell. In a third aspect, the invention features a method of producing a somatic grape embryo. The method includes the general steps of (a) pro-viding a liquid culture that includes an embryogenic cell and medium consisting of B-5 major salts and MS minor salts, (b) recovering the embryogenic cell from the culture, (c) transfer-ring the embryogenic cell to a second culture, and (d) growing a somatic grape embryo from the embryogenic cell












Sources :

Sahijram, L., & Bahadur, B. (2015). Somatic embryogenesis. Plant Biology and Biotechnology: Volume II: Plant Genomics and Biotechnology, 315-327.

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