Plant Cloning Flashcards
(13 cards)
What asexual reproduction?
- form of cloning
- results in offspring genetically identical to parent by mitosis.
What is natural plant cloning/ vegetative propagation?
- structure forms -> develops into fully differentiated new plant = genetically identical to parent
- involved parrenating organs -> so plants can survive winter -> contain food from photosynthesis -> remain dormant in soil e.g. bulbs, runners, stem tubers .
What is artificial cloning?
- using natural plant cloning in horticulture (farmers take advantage of natural plant cloning to make new plants).
E.g. splitting up bulbs. - take “cutting” (short sections of stem -> planting them into ground/pots) -> used for few not large number of plants.
How to take cuttings.
1- cut stem between 2 leaf joints (nodes).
2- leave 2-3 leaves attached -> remove lower ones.
3- cut at 45 degree angle -> increase SA -> helps it take up water.
4- dip bottom of stem into “rooting power” containing plant hormones (like auxin) -> stimulate new roots to grow.
5- kept well watered -> roots establish + leaves develop.
6- plastic bag around pot helps plant -> low transpiration maintains turgor.
7- once cutting can support itself -> it can be planted out.
Advantages of taking cuttings.
- Faster than sexual reproduction which requires pollination/seed production/ germination/ growth time into new plant -> harvesting plant takes time.
- Guarantees quality of crop plant produced -> original plant has useful characteristics -> all offspring genetically identical.
Disadvantage of taking cuttings.
Decrease genetic variation -> whole crop at risk at failure of climate changes and if new disease/pest is introduced.
Things that increase cutting success.
1- non-flowering stem -> energy goes to new root growth not flower production.
2- 45 degrees angle cut on stem -> increase SA.
3- hormone rooting pressure -> stimulates new roots to grow.
4- leave 2/4 leaves - decrease transpiration -> maintain turgor.
5- well watered cutting - roots establish and leaves develop.
6- plastic bag - increase humidity -> water vapour loss.
What is microprogation used for?
- For producing large number of clones.
- plant cells can be totipotent (differentiate into all diff cell types in plants).
What is micropropagation?
Process of making large numbers of genetically identical offspring from single parent plant using tissue culture techniques.
When is it used?
Used when a desirable plant:
- doesn’t readily produce seeds.
- Doesn’t respond well to natural cloning.
- is very rare.
-has been GM/ selectively bred with difficultly.
- needs to be pathogen free.
Method of micropropagation.
1- take a small sample of tissue from meristem (undifferentiated) -> explant. Make sure of sterile working conditions (no bacteria/fungi contamination).
2- sterile sample -> immerse into ethanol/ bleach (dilute).
3- explant placed on sterile culture medium containing nutrients and balance of plant hormones (cytokines) -> stimulate mitosis -> from undifferentiated mass of cells (callus and totipotent).
Nutrients needed -> glucose (resp), a.a (PS), mineral ions (ATP).
4- Calluls divided into smaller groups of cells -> transferred to culture medium containing nutrients-> with diff balance off hormones and nutrients to stimulate development of shoots and roots.
5- lots of tiny genetically identical plants (plantlers) -> potted into compost -> grew into small plants.
6- when strong enough -> planted to produce crop of desired plant.
Positives of microprogation.
- lots of genetically identical plants produced quickly.
- all have same characteristics - guaranteed qualities - uniform - ready to harvest at same time
- offspring all pathogen free
- can be used to increase number of rare species where SR impossible
Disadvantages of micropropagation.
- Initial start up cost high - sterile lab, trained staff, specialist, equipment, lightning.
- decrease of genetic variation - all susceptible to some diseases/change in climate
- if contamination occurs -> whole batch thrown away -> money.
