Plant Cloning (Micropropagation)

Plant Cloning (Micropropagation)
And Revision
Tissue Culture
Vegetative propagation:
Stem, leaf or root cuttings
Micropropagation (tissue culture)
What are needed in micropropagation?
Tissue culture nutrient medium
(1) essential elements, or mineral ions, supplied as a complex mixture of salts;
(2) an organic supplement supplying vitamins and/or amino acids; and
(3) a source of fixed carbon: sucrose.
2. Plant growth regulators (Plant hormones)
Auxin
Cytokinin
3. Carefully controlled environment
Aseptic environment
No bacteria, fungus, virus, etc.

Step 1: Surface sterilization of explants
Small pieces of tissue (explants) removed from any part of the plant
May be meristematic (such as the shoot tip, the root tip), or non-meristematic (leaf parts).
First surface sterilized
Transferred in sterile surroundings to a sterile medium

Step 2: Callus formation (induction)
A callus is a mass of undifferentiated cell mass formed by mitosis

During callus formation, there is dedifferentiation
Consequence  lose the ability to photosynthesise.
Plant tissue culture cells have a small vacuole, lack chloroplasts and photosynthetic pathways and the structural or chemical features
Callus can later be induced to re-differentiate into whole plants by alterations to the growth media
Step 3: Subculturing
Aim:
callus can be subdivided to increase the number of plants eventually produced
Step 4: Shoots and roots formation
Auxin to cytokinin ratio
Step 5: Acclimatization followed by transplanting
Acclimatization allows environmental and physiological adaptation of tissue cultured plants to a greenhouse or a field environment
Before transplanting the plantlets

Advantages
extremely high multiplication rates.
identical copies of plants with desirable traits
Both seeds and pollinators are not required.
Plant cells can be genetically modified.
Limitations
aseptic condition requirements
A virus infection would quickly destroy a batch of plants
Suitable techniques of micropropagation are not available for many valuable species
Somaclonal variation may arise during in vitro culture
Revision/ Clarification
Tutorial: Enzymes
The initial rate of a reaction catalysed by an enzyme was measured at various substrate concentrations. Which graph shows the effect of a low concentration of non-competitive inhibitor on the reaction?