22.2 Artifical Cloning In Plants

Question 1

What is tissue culture?
How is it carried out?

Answer 1

An artificial way of cloning plants.

1) cells are taken from the original plant that’s going to be cloned. Cells from the stem and root tips are taken as they are stem cells. The material from the plant is called the explant.

2) the cells are sterilised (immerse the sample in bleach/ ethanol) to kills any microorganisms — bacteria and fungi compete for nutrients with the plant cells, which decreases their growth rate

3) the cells are placed on a culture medium containing organic nutrients (like glucose and amino acids) and a high concentration of plant hormones (e.g. auxins and cytokinins) which stimulate mitosis.
This is carried out under aseptic conditions..
The cells divide to produce a mass of undifferentiated cells (called callus).
The callus can be subdivided into groups that are transferred to a new culture medium to produce lots of plantlets very quickly.

4) when the cells have divided and grown into a small plant they’re taken out of the medium and planted in soil— they’ll develop into plants that are genetically identical to the original plant

Question 2

Uses of tissue culture

Answer 2

Used to clone plants that don’t readily reproduce, is endangered, rare, required to be pathogen free by growers e.g. bananas

Question 3

Describe and explain micropropagation

Answer 3

Is when tissue culture is used to produce lots of clones plants very quickly.

Cells are taken from developing cloned plants and subcultures (grown on another fresh culture medium)

This technique is used in horticulture and agriculture (e.g. to produce fields full of a crop that has been genetically engineered to be pest-resistant)

Question 4

Advantages for micropropagation (artificial plant cloning)

Answer 4

• desirable genetic characteristics (e.g. high fruit production) are always passed on to clone
• tissue culture allows plants to be reproduced in any season because the environment is controlled
• less space is required by tissue culture
• it produces lots of plants quickly compared to the time it would take to grow them in seeds
• can produce disease free plants
• reliably increase numbers of rare or endangered plants

Question 5

Arguments against micropropagation

Answer 5

• undesirable characteristics (e.g. producing fruits with lots of seeds) are always passed on to clones
• clones plant populations have no genetic variation (monoculture), so a single disease/ change in environment can affect them all
• expensive process and skilled workers are required
• contamination by microorganisms during tissue culture can be disastrous and result in complete loss of the plants being cultured