Plant Tissue Culture

Question 1

Describe plant tissue culture.

Answer 1

Plant tissue culture is the in vitro cultivation of plant cells, tissues or organs under artificial medium and controlled environmental conditions to propagate plants in large quantities in a short period of time.

Question 2

What is the basis behind plant tissue culture?

Answer 2

Totipotency. The basis that plant cells are able to differentiate into shoots leaves, and roots of a new plant under optimum conditions.

Question 3

What are some examples of PTC?

Answer 3

• Seeding and seedling culture: Growing seeds under artificial medium.
• Embryo culture: Growing embryos under an artificial medium
• Organ culture: Using parts of plant to regenerate new plants.

Question 4

What are the three major factors that determines the success of PTC?

Answer 4

Environmental (Maintain sterile environment, pH, temperature)
Selecting correct composition of growth medium, (Macro, micronutrients, growth regulators)
Source of explant (younger, less differentiated is better)

Question 5

What are the four stages of plant cultures?

Answer 5

IRRA:

• Initiation of Culture
• Regeneration of shoot
• Rooting of regenerated shoot
• Acclimatization of plant in soil.

Question 6

What are some components of plant tissue culture medium?

Answer 6

• Mineral salts, Solidifying agent (agar), growth regulators (auxins and cytokinins), Vitamins, sucrose

Question 7

What are the purpose of auxin and cytokinin?

Answer 7

Auxin: Induce leaf development, low concentrations induce root tip elongation
Cytokinin: Induce cell division.

Question 8

How does regulating the cytokinin/auxin ratio affect the development of plants in PTC?

Answer 8

High CA ratio favor shoot generation
Low CA ratio favor root growth
High concentrations of both cytokinin and auxin induce the formation of callus.

Question 9

Describe micropropagation.

Answer 9

Micropropagation is a method of plant tissue culture where:

1. Small piece of plant tissue from donor is cultured on a medium (organ culture)
2. The environmental conditions and composition of medium is altered to direct the development of tissue.
3. An entire plant can be regenerated, clones of the mother plant can be produced.

Question 10

What are the stages of micropropagation?

Answer 10

SMRT:

• Selection of explant and initiation of culture
• Multiplication
• Regeneration
• Transfer to soil and hardening.

Question 11

What is the purpose of hardening in micropropagation?

Answer 11

In vitro plant material is not adapted for in vivo conditions, hardening adapts an organism to environmental change via acclimatization.

Question 12

What are the components of the Ti plasmid of Agrobacterium Tumefaciens?

Answer 12

• tDNA section: The cloning site (site to be cut), codes for auxin and cytokinin and causes unregulated, cancerous growth in plants
• NPTII selection gene: Selection gene that codes for neomycin phophostransferase and confers kanamycin resistance
• GUS selection gene: Codes for B-glucuronidase which breaks down X-Glue to form blue product.