Basic Concepts
What is plant tissue culture?
Growing plant cells, tissues or organs in vitro under controlled conditions on artificial media.
What are the 3 main parts of plant culture media?
Mineral salts, organic supplements amd carbon source.
What happens when auxin is higher than cytokinin?
Roots form
What is an explant?
A sterile plant part used to start culture.
Name 2 methods of plant regeneration.
Somatic embryogenesis and organogenesis.
What does "in vitro" mean in plant tissue culture?
Growing outside the organism, in a laboratory environment.
What is the function of organic supplements?
Supplying vitamins and amino acids.
Which harmone inhibits growth and embryo development?
ABA
What is suspension culture?
Cells growing in liquid medium.
What is somatic embryogenesis?
Formation of embryos from somatic cells.
What does plasticity mean?
The ability of plant cells to change their development depending on environmental conditions.
Why is EDTA added with iron?
To chelate iron, prevent precipitation and to allow slow iron release.
Why are hormones important in tissue culture?
They control cell division and development.
How is suspensiom culture produced?
By placing friable callus in liquid medium and shaking.
Name stages of somatic embryo development.
1. Single cell/ group of cells
2. Globular stage
3.Heart stage
4.Torpedo stage
5. Plantlet formation
Give one example of plant cell plasticity.
Leaf cell forming root or Steam tissue forming shoot or Callus forming whole plant.
State the function of Magnesium in culture environment.
Enzyme cofactor, component of chlorophyll.
A culture initially produces callus when both auxin and cytokinin are present. The scientist then increases cytokinin concentration while keeping auxin low. This change will most likely result in what developmental structure?
The developmental outcome will shift from callus to shoot formation.
Why is callus often grown in the dark?
To prevent differentiation
What is the role of totipotency in regeneration?
It allows cells to develop into complete plants.
Why must cells receive external nutrients in culture?
Because they are outside of the plant and cannot obtain nutrients naturally.
Which element provides cell wall synthesis, membrane function and cell signaling?
Calcium
Callus forms rapidly in media containing both auxin and cytokinin. This indicates these hormones share what common cellular function?
Cell division
A researcher notices that callus derived from an older leaf tissue fails to regenerate into shoots, while callus from young leaf tissue regenerates efficiently. Explain why this happens and suggest a strategy to improve regeneration from older tissue.
Because older tissues have lower cell division rates, reduced totipotency and more differentiated cells.
Strategy: treat older tissues with higher auxin/cytokinin ratio.
A researcher uses high level of 2,4-D to induce embryogenesis. However, embryos fail to develop further. This shows what role of auxin in somatic embryogenesis?
For embryo initiation high level of 2,4-D is required, but for further embryo development level of 2,4-D must be reduced or removed.