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jaisreenivasan
PLANT TISSUE CULTURE
An IntroductionPlant tissue culture is:A tool in biotechnology, used in micropropagation, secondary metabolic production(taxol), hybridisation etc.It refers to the growth of plant parts(organs, tissues etc.) in a sterile environment in a nutrient medium.
Why Plant T.C.?? Saves time & labour in comparison to
conventional hybridization techniques. Useful when other techniques are not
useful. Eg.: Apical meristems which are free of
viruses(present in shoot tips) can be harvested & nurtured to grow into virus-free plants in times of viral attack.
Uses• To save species from extinction• To isolate disease from plants • To produce plants with enhanced
stress or pest resistance• To create new plant varieties • To make money
Speed of multiplication in T.C.
Totipotency Plant tissue culture is based on
totipotency Plant cells have the ability to produce
the whole plant from single cells. This is called totipotency.
Plants have the ability to reproduce asexually through a type of cell division- mitosis.
Mitosis
• Daughter cells of identical chromosome numbers are produced.
Beginning of T.C. In 1902, a German physiologist, Gottlieb
Haberlandt proposed that single plant cells could be cultured.
He isolated single fully differentiated individual plant cells from different plant species and was first to culture them in Knop’s salt solution enriched with glucose.
History-1930s In the 1930s, importance of vitamins
was determined for shoot and root culturing
Indole-Acetic Acid(IAA), a natural auxin, and the most important, was discovered during the 1930s.
Many more synthetic auxins were discovered. Eg.: 2,4d & NAA(Napthaleneacetic acid)
History-1957-58 Miller and Skoog discovered kinetin, a
synthetic cytokinin, in the University of Wisconsin – Madison.
Kinetin plays active role in organogenesis.
Steward developed somatic embryo from carrot cells
History-1958-60 Morel cultured orchids and dahlias & freed them
from a viral disease
History-1962• Murashige and Skoog published recipe for MS
Medium for T.C.
T.C. Medium Functions: provide H2O, provide mineral &
vitamin nutritional needs. H2O is usually distilled minerals must provide 17 essential elements energy source - sucrose is preferred provide access to atmosphere for gas
exchange serve as a dumping ground for plant
metabolites
T.C. medium Macronutrients-eg: K, Ca, Mg, N, P, O
etc. Micronutrients-eg: Fe, Mn, Mo, etc. Vitamins & Amino acids:thiamine,
pyridoxin, nicotinic acid, biotin, citric acid, ascorbic acid, Inositol, Glycine etc.
Growth Regulators: auxins and cytokinins
Carbon Source:Sucrose pH usually 5.0-5.7
T.C. Steps1. Explant collection2. Callus generation3. Organogenesis (shoot and root
induction)4. Hardening Micropropagation does not involve the
second step. There is direct organogenesis.
Explant collection
portion of plant removed and used for T.C.
Important features size source - some tissues
are better than others species dependent physiological age -
young portions of plant are most successful
Explant collection degree of contamination external infestation - soak plant
in sodium hypochlorite solution internal infection - isolate cell
that is not infected roots - especially difficult
because of soil contact herbaceous plants soft stem easier to culture than woody
plants
Callus Generation•The dedifferentiation of a plant cell(explant) produces callus. •Callus is then expanded into a larger mass of undifferentiated cells.•Callus is then activated, by selective use of plant hormones to redifferentiate to produce, shoots, roots and ultimately, plantlets
Organogenesis Usually induced by changes in hormonal
environment Shooting: Higher cytokinin
concentration & lower auxin concentration(cytokinins promote shoot growth).
Rooting: lower cytokinin concentration and increase auxin(auxins promote shoot growth)
Hardening Hardening involves the formation of the
waxy cuticle on the leaves of the plant. Plants in T.C. do not have cuticle usually done in greenhouse with high
relative humidity(RH). gradually increase light intensity and
lower RH after rooting occurs allows plants to harden and helps plants
form cuticle
CREDITS TO The inventors of tissue culture Google images The internet’s information Microsoft Office 2010
THANK YOU!!