Cloning in plants Flashcards
What is cloning?
Genetically identical to both parent organism + to each other
–> asexual reproduction: produced by mitosis
What is vegetative propagation?
Form of asexual reproduction.
New, genetically identical individuals develop from non-reproductive tissues of a parent plant such as its roots, stems, and leaves.
Often
What does vegetative propagation often involve?
Perennating organs: enables plant survive adverse conditions
–> contain stored food from photosynthesis –> remain dormant in soil.
Survive between growing seasons
Example of natural plant clones:
Bulbs: (daffodil) leaf base swell with stored food from photosynthesis –> new shoots develop
Runners: (strawberry) lateral stem grows away from parent plant + roots develop where runners touch the ground.
Rhizomes: (marram grass) specialised horizontal stem running underground –
> swollen with stored food. Buds develop = new vertical shoots.
Stem tubers (potato): tip of underground stem beomes swollen with stored food -> form tuber (storage organ)
How to use natural cloning as horitculture?
Splitting up bulbs + removing young plants from runners increase plant numbers cheaply.
new plant = exact genentic material as parent
Cuttings + rooting hormone
Advantages of cuttings over planting seeds?
Faster –> time from planting to cropping is reduced
Cost effective
Guarentees quality of plant
–> identical offspring
Ensures high yield
Plant can survive adverse conditions + regenerate each season.
Disadvantages of cuttings over planting seeds?
Lack of genetic variation in offspring:
-> climate change
-> new disease/pest
How to increase success rate iof cuttings?
Use non-flowering stem
Make oblique (slanted) cut in stem
Use hormone rooting powder
Reduce leaves to 2/4
Keep cuttings well watered
Cover cuttings with plastic bag
Define micropropagation:
Process of making large numbers of G.I offspring from 1 parent plant using tissue culture techniques.
Define tissue culture:
Involves growing plant tissues in a sterile medium with hormones (auxins/ cytokinins) –> stimulate cell division + growth.
When is micropropagation used?
- Plant not produce seeds
- Doesnt repsond well to natural cloning
- Rare
- Genetically modified/selectively bred with difficulty
- Required to be ‘pathogen free’ by growers
What are the steps in making tissue culture for micropropagation?
Collect explant: small tissue samples (shoots/roots) taken from parent
Sterilisation: (ethanol/bleach) inhibit growth of contaminants –> reduces risk of widespread infection (healthier crops)
Culture: explant cultured on nutrient-rich medium –> support rapid cell division + growth
Development: explant divide -> undifferentiated mass of cells = callus
–> transferred to new medium = specific conditions = shoot/root formation
Callus differentiate into plantlets
Transfer: fully formed plantlets –> moved to growth medium (soil)
–> develop into mature identical plant
What are the applications of micropropagation?
Rapid + large-scale propagation of plants (rare/endangered or reproduce slowly)
Produces disease-free clones of crops + preserving valuable genetic resources
Allows mass production of GM plants –> those engineered for herbicide resistance
Produces seedless plants/ plants difficult to cultivate from seeds
Advantages of micropropagation:
- Produces G.I plants –> reliable inheritance of traits = high yield
- All times of year
- Space-efficient
- Rapidly produces large number of mature plants
- Important for commerical plant procutions + conservation efforts
Disadvantages of micropropagation:
- G.I (monoculture) so crops vulnerable to disease + environmental changes
- May unintentionally propagate undesirable traits.
- Expensiven+ requires skilled techs –> less feasible on small scale.
- Explants/plantlets vulnerable to infection –> increasing risk of total crop loss.
