organogenesis and somatic embryogenesis.pptx

Organogenesis and somatic embryogenesis
Biotechnology of fruit crops

1. ORGANOGENESIS AND SOMATIC EMBRYOGENESIS Reema Naik Fruit science

2. PLANT TISSUE CULTURE : Plant tissue culture is the aseptic method of growing cells and organ such as leaves, roots, meristems, etc either in solid or liquid medium under controlled condition. The three common pathways of plant tissue culture regeneration are ; Propogation from pre-existing meristems(Shoot culture or Nodal culture) Organogenesis Non Zygotic (Somatic) embryogenesis

3. ORGANOGENESIS A plant contains many organs like meristems ,cortex , phloems , epidemis are consist of structural unit called cell. Because an cell have to nature of create whole plant like any organ or tissue of plant also show same nature mean they also create to whole plant in In-Vitro Condition. If plant organs used in in-vitro conditions to generated new plant this process called Organogenesis.

4. organogenesis the development of adventitious organs or primordia from undifferentiated cell mass in tissue culture by the process of differentiation is called organogenesis. OR “The formation of roots , shoots or flower buds from the cells in culture in manner similar to adventitious root or shoots formation in cuttings is called Organogenesis. CAULOGENESIS: It is a type of organogenesis by which only adventitious shoot bud initiation take place in the callus tissue. RHIZOGENESIS: It is a type of organogenesis by which only adventitious root formation takes place in the callus tissues.

5. Types of Organogenesis In plant tissue culture, undifferentiated tissue is referred to as callus although a callus can contain meristematic nodule that may not be obvious to the naked eye but which never develop further unless suitable conditions are supplied. DEVELOPMENT OF ORGANISED STRUCTURES CAN FOLLOW ONE OF THE THREE PATHWAYS. Shoot regeneration , based on a unipolar structure with a shoot apical meristems. Root regeneration , essentially a unipolar structure with a root apical meristems. Somatic embryogenesis in which there is bipolar structure.

6. a)Indirect organogenesis Plant organ formation on callus tissues derived from explants. Plant growth regulators and differentiation The classic observation of Skoog and miller that the directions of differentiation could be influenced by the ratio of the exogenously supplied growth regulators auxin and cytokinin. They observed in tobacco stem pith cultures that a high ratio of auxin to cytokinin led to initiation of roots whereas a low ratio led to developments of shoots. Although there are many species for which this simple manipulation will not work, in general auxin e.g. IAA, NAA will stimulate regeneration of roots, and cytokinins e.g. BAP will promote regeneration of shoots or embryos.

7. b) Direct Organogenesis Formation of organs directly on the surface of cultured intact explants. The process does not involve callus formation. The role of growth regulators Direct organogenesis bypasses the need for a callus phase. A good example is the formation of somatic embryos. Most evidence suggests that direct embryogenesis proceeds from cells which were already embryogenically competent while they were part of original, differentiated tissue.

8. Applications of organogenesis Plant tissue culture or organogenesis has direct commercial applications as well as value in basic research into cell biology, genetics and biochemistry. Micropropogation using meristems and shoot culture to produce large number of identical individuals. Screening programmes of cells, rather than plants for advantageous characters. Large scale growth of plant cells in liquid culture as a source of secondary products. Removal of viruses by propogation from meristematic tissue.

9. Factors affecting the organogenesis In vitro organogenesis is controlled by a number of factors other than phytohormones this are as follows: Size of explant : Organogenesis is generally dependent upon size of explant. The large explant consisting parenchyma, vascular tissues and cambium have greater regenerative ability than the smaller explant. Source of explant : the most suitable part of the plant for starting culture will depend on species. Leaves and leaf fragment of many plant species like Begonia, solanum, Nicotina , Crepis , etc. have shown capacity to regenerate shoot buds. Age of the explant : Physiological age of explant is important for in vitro organogenesis. In Nicotiana species, regeneration of adventitious shoot is only noted if the leaf explant is collected from vegetative stage. i.e. before flowering.

10. Oxygen gradient : in some cultures , shoot bud formation takes place when the gradient of available oxygen inside the culture vessel is reduce. But rooting require a high oxygen gradient. Quality and intensity of light : the blue region of spectrum promotes shoot formation and red light induce rooting. Temperature : most tissue culture are grown successfully at temp. around 250 c PH of the medium : the Ph of the culture medium is genrally adjusted between 5.6-5.8 before stirilization . The Ph may have determining role in organogenesis. Age of culture: a young cultures frequently produces organs. But the orgaogenic potential may decrease and ultimately disappear in old culture .

11. Embryogenesis Somatic Embryogenesis “The process of a single cell or a group of cells initiating the developmental pathway that leads to reproducible regeneration of non-zygotic embryos capable of germinating to form complete plants.” Under natural conditions this pathway is not normally followed, but from tissue cultures somatic embryogenesis occurs most frequently and as an alternative to organogenesis for regeneration of whole plants.

12. In somatic embryogenesis, embryo like structures, which can develop into whole plants in a way analogous to zygotic embryos, are formed from somatic tissues. These somatic embryos can be produced either directly or indirectly. Two ways of somatic embryogenesis: Direct embryogenesis Indirect embryogenesis

13. Direct embryogenesis in direct somatic embryogenesis, the embryo is formed directly from a cell or small group of cells without the production of intervening callus. Direct somatic embryogenesis is generally rare in comparison with indirect somatic embryogenesis. Indirect embryogenesis In indirect somatic embryogenesis, callus is first produced from the explant. Embryos can then be produced from the callus tissue or from a cell suspension produced from that callus.

14. Importance of somatic embryogenesis In poly embryonic crops like citrus, zygotic as well as nucellar embryonic plants are obtained separately. Embryos of big and heavy fruits like coconut can be taken out of the fruits and pre-serve in tube in sterile distilled water for about two months and then cultured in media. In this process easy international exchange of germplasm is possible. One major path of regeneration. Mass multiplication. Production of artificial seeds. suitable in suspension culture. Higher propogation rates.

15. Stages of somatic embryogenesis Somatic embryogenesis encompasses various stages such as Callus initiation Embryo development and maturation Plantlet formation

16. Advantages It is observable, as its various culture condition can be controlled Lack of material is not a limiting is not a limiting factor for experimentation High propogation rate Somaclonal variation Germplasm conservation Labour saving Elimination of diseases and virus

17. Disadvantages Confined to few species The somatic embryos show very poor germination because of their physiological and biochemical immaturity. Instability of cultured cells in long-term cultures is a major limitation in commercial exploitation and mass propogation .