Natural and artificial plant cloning

In a nutshell

Plants can make clones of themselves naturally via vegetative propagation. These natural methods can be exploited by horticulturists to produce clones with desirable features. This is done by taking plant cuttings. Plants can also be cloned artificially using tissue culture.

Cloning

Definition

Cloning uses the cells of an existing organism to produce genetically identical organisms or cells. It occurs naturally in some plants or animals but it can be carried out artificially to produce many identical organisms with a desirable characteristic.

Vegetative propagation

Definition

Vegetative propagation involves producing genetically identical plant clones from non-reproductive tissues such as roots, stems and leaves. There are many different methods that can be used.

Method	Description	Example
Rhizomes	These are horizontal stems that grow underground away from the parent plant. New shoots and roots grow from nodes on these stems.	Ginger
Runners/Stolons	These are horizontal stems that grow above ground. New shoots and roots grow from nodes or form at the end of the stolon.	Jasmine flower
Suckers	These are new stems that grow from undeveloped shoots on the root of the plant. The undeveloped shoots are known as sucker buds.	Lilac
Tubers	These are large, underground structures that provide a source of food to the plant. They are covered in eyes that sprout and form new plants.	Potatoes
Bulbs	Bulbs are made up of an underground stem that grows into a series of fleshy leaf bases. The bulbs contain at least one apical bulb that will grow into a new plant.	Hyacinths (a type of flowering plant)
Corms	These are underground stems with scaly leaves and buds. The buds grow into new plants. Corms are visually similar to bulbs, however, they are solid.	Taro (a root vegetable)

Cuttings

Growing the cuttings of a plant is way to produce clones.

Method

Biology; Cloning and biotechnology; KS5 Year 12; Natural and artificial plant cloning

1.	Using a scalpel, take a $5\ cm$ to $10\ cm$ cutting from the stem, root or leaf of the parent plant.
2.	If you have taken a stem cutting, you should remove the leaves from the lower end and leave just one leaf at the tip.
	If you have taken a root cutting, it needs to have a straight cut. Then you should take the uncut end and cut it in a slanted direction.
	One type of leaf cutting is known as split vein cutting. If you are following this method then you should remove the whole leaf and score the large veins on the lower surface.
3.	Next, you should dip the lower end of the cutting into rooting power. This contains hormones that trigger root formation.
4.	Your cutting should then be placed in a pot with a suitable growth medium. If you are doing a split vein cutting, the leaf should be placed on top of the growth medium with the broken veins facing down.
5.	A propagator can then be used to provide the cutting with ideal conditions. Alternatively, the cutting should be put into a warm and moist environment.
6.	The cutting should then form its own roots. It will then be strong enough to be planted elsewhere, where it can continue to grow.

Artificial cloning

Using tissue culture, plants can be artificially cloned. It is used to clone plants that do not reproduce easily or are endangered and/or rare. Tissue culture can also be used to grow whole plants from genetically engineered plants.

Method

Biology; Cloning and biotechnology; KS5 Year 12; Natural and artificial plant cloning

1.	Cells are taken from the parent plant. These cells are taken from the roots and stems because they are stem cells.
2.	The cells are then sterilised to kill any microorganisms that may compete with the plant for nutrients and affect their growth.
3.	The cells are then placed on a culture medium that contains growth hormones and nutrients.
4.	The cells will divide and grow into a small plant that can then be planted into soil.

Micropropagation

Micropropagation is when tissue culture is used to produce large numbers of clones very quickly. Cells are repeatedly taken from developing cloned plants and subcultured. This is widely used in horticulture and agriculture as it can produce many plants with desirable characteristics in a short period of time.

Advantages and disadvantages

Advantages	Disadvantages
Artificial cloning ensures desirable characteristics are always passed onto offspring. This is not guaranteed with sexual reproduction.	Artificial cloning ensures undesirable characteristics are always passed onto offspring.
Tissue culture is not affected by seasons as plants are grown in controlled conditions.	There is a lack of genetic diversity within cloned plants. This means one disease could kill them all.
Tissue culture requires less space than other methods and it is a quick process.	Tissue culture is very expensive as it requires a lot of energy, many skilled workers and specialist equipment to maintain the environment.