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Plant Tissue Culture. T.C. Refers to technique of growing plant cells, tissues, organs, seeds or other plant parts in a sterile environment on a nutrient medium. History. In 1902 Haberlandt proposed that single plant cells could be cultured. Haberlandt. did not culture them himself.
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T.C. • Refers to technique of growing plant cells, tissues, organs, seeds • or other plant parts in a sterile environment on a nutrient medium
History • In 1902 Haberlandt proposed that single plant cells could be cultured
Haberlandt • did not culture them himself
1930’s • White worked on T.C. • discovery of plant growth regulators
1930’s • importance of vitamins was determined for shoot and root culturing A,D,E,K,C, B complex
1930’s • Indole-Acetic Acid • IAA • discovered in 1937
IAA • 2,4-D • Dicamba • NAA • IBA • all synthetic hormones
1957-58 • Miller and Skoog • University of Wisconsin - Madison • discovered Kinetin
Kinetin • a cytokinin • plays active role in organogenesis
1958 • Steward developed somatic embryo from carrot cells
1958-60 • Morel cultured orchids and dahlias • freed them from a viral disease
1962 • Murashige and Skoog • published recipe for MS Medium
60’s & 70’s • Murashige cloned plants in vitro • promoted development of commercial plant T.C. labs
1966 • raised haploid plants from pollen grains
1972 • used protoplast fusion to hybridize 2 species of tobacco into one plant • contained 4N
4N • all chromosomes of both plants
70’s &80’s • develop techniques to introduce foreign DNA into plant cells • beginning of genetic engineering
T.C. Media • functions • provide H2O • provide mineral nutritional needs
T.C. Media • provide growth regulators • Provide vitamins • provide organic compounds
T.C. Media • provide access to atmosphere for gas exchange • serve as a dumping ground for plant metabolites
T.C. Media • H2O is usually distilled • minerals must provide 17 essential elements • energy source and carbon skeletons - sucrose is preferred
Vitamins • thiamine • pyridoxin • nicotinic acid • biotin
Vitamins • citric acid • ascorbic acid • inositol
Growth Regulators • auxins and cytokinins • gibberellic acid • abscissic acid
pH of media • usually 5.0-5.7
Media • must be sterile • autoclave at 250 F at 15 psi for 15 minutes
T.C. Stages • Explanting- Stage I • get plant material in sterile culture so it survives • provide with nutritional and light needs for growth
Stage II • rapid multiplication • stabilized culture • goal for a commercial lab • difficult and time consuming to maintain
Stage II • occurs in different pathways in different plants
Rooting - Stage III • may occur in Stage II • usually induced by changes in hormonal environment • lower cytokinin concentration and increase auxin
Rooting • may skip stage III and root in a greenhouse
Stage IV • transplantation and aftercare • usually done in greenhouse • keep RH high (relative humidity)
Stage IV • gradually increase light intensity and lower RH after rooting occurs • allows plants to harden and helps plants form cuticle
Cuticle • waxy substance promotes development of stomates • plants in T.C. don’t have cuticle
Explant • portion of plant removed and used for T.C. • Important features • size • source - some tissues are better than others
Explant • species dependent • physiological age - young portions of plant are most successful
Explant • degree of contamination • external infestation - soak plant in sodium hypochlorite solution
Explant • internal infection - isolate cell that is not infected • roots - especially difficult because of soil contact
Explant • herbaceous plants • soft stem • easier to culture than woody plants
Patterns of multiplication • stage II - light 100-300 foot candles • callus - shoots - roots • stage III - rooting - light intensity 1000-3000 foot candles
Genetic transformation • permanent incorporation of new or foreigh DNA into genome of cell
Transformation methods • protoplast fusion • cell wall is enzymatically removed from cell
Protoplasts • naked plant cells • from 2 different plants can be mixed together and forced to fuse
Protoplast fusion • results in heterokaryon • cell containing two or more nuclei from different cells • homokaryon - from same cell
Protoplast fusion • allowed to regenerate cell wall and then grow into callus • callus turns to shoots
Shotgun approach • DNA coated micro bullets of gold or tungston • shot into growing cells • DuPont holds the patent
Shotgun approach • injures cells • random success rate
PEG • Polyethylene glycol • pores open similar to electroporation
Ti Plasmids • Tumor inducing • Agrobacterium temefasciens • infect cells with agrobacterium which contains desired DNA