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Micropropagation for Large-Scale Production of Crop Plants

Micropropagation for Large-Scale Production of Crop Plants – Detailed Notes


1. Introduction


Micropropagation is an in-vitro clonal propagation technique used for the rapid multiplication of plants under aseptic and controlled laboratory conditions. It is a major application of plant tissue culture, allowing large-scale production of genetically identical plants (clones) from a small piece of plant tissue (explant).
This technique is widely used for crop plants, horticultural plants, ornamentals, forest trees, and medicinal plants.


2. Principle of Micropropagation


Micropropagation is based on the concept of totipotency, which states that:
Every living plant cell has the genetic potential to regenerate into a complete plant under suitable conditions.
By providing appropriate nutrients, hormones, light, temperature, and sterile conditions, a single explant can produce thousands of plantlets.


3. Stages of Micropropagation


Micropropagation is carried out in five distinct stages:


Stage I – Selection and Preparation of Explant
Healthy, disease-free mother plant is selected.


Explants used:


Apical meristem
Axillary bud
Nodal segment
Leaf, root, or embryo
Explant is surface sterilized using:
Alcohol (70%)
Sodium hypochlorite / Mercuric chloride


Aim: Establishment of aseptic culture


Stage II – Initiation of Culture
Explant is inoculated onto nutrient medium (usually MS medium – Murashige and Skoog medium).
Medium contains:
Macronutrients & micronutrients
Vitamins
Carbon source (sucrose)
Plant growth regulators
Cytokinins (BAP, kinetin) promote shoot initiation.


Stage III – Multiplication


Rapid multiplication of shoots occurs.
High cytokinin concentration induces:
Axillary bud proliferation
Multiple shoot formation
Repeated sub-culturing increases the number of shoots exponentially.
This stage is crucial for large-scale production.


Stage IV – Rooting


Shoots are transferred to rooting medium.
Auxins used:
IAA
IBA
NAA
Roots develop, forming complete plantlets.


Stage V – Hardening (Acclimatization)


In-vitro plantlets are delicate and cannot survive directly in soil.
Gradual exposure to:
Reduced humidity
Natural light
Plantlets are transferred to:
Greenhouse
Polyhouse
Nursery
Finally shifted to field conditions.


4. Culture Media Used


Murashige and Skoog (MS) Medium
Components:
Macronutrients: N, P, K, Ca, Mg
Micronutrients: Fe, Mn, Zn, Cu
Vitamins: Thiamine, Nicotinic acid
Carbon source: Sucrose
Gelling agent: Agar


5. Methods of Micropropagation


Meristem culture
Axillary bud culture
Adventitious shoot formation
Somatic embryogenesis
Callus culture


6. Crop Plants Produced by Micropropagation


Food crops: Banana, Potato, Sugarcane, Rice
Horticultural crops: Tomato, Strawberry
Plantation crops: Tea, Coffee
Spices: Ginger, Turmeric
Ornamental plants: Orchid, Rose, Chrysanthemum
Medicinal plants: Aloe vera, Neem


7. Advantages of Micropropagation


Rapid multiplication of plants
Year-round production
Genetically uniform plants
Disease-free planting material
Requires small space
Conservation of elite and endangered species


8. Limitations of Micropropagation


High initial cost
Requires skilled manpower
Risk of somaclonal variation
Contamination problems
Not economical for all crops


9. Applications in Large-Scale Crop Production


Production of virus-free plants
Commercial nursery production
Germplasm conservation
Rapid spread of improved varieties
Biotechnology and genetic engineering programs


10. Conclusion
Micropropagation is a powerful biotechnology tool for large-scale production of crop plants. It ensures uniform, disease-free, and high-quality planting material, playing a crucial role in modern agriculture, horticulture, and food security.






Micropropagation is a technique of
A. Sexual reproduction
B. Asexual reproduction
C. Seed germination
D. Hybridization
Answer: B
The basic principle of micropropagation is
A. Mutation
B. Hybrid vigor
C. Totipotency
D. Differentiation
Answer: C
Totipotency means
A. Cell division
B. Ability of cell to photosynthesize
C. Ability of a single cell to regenerate into a whole plant
D. Ability to form callus
Answer: C
Micropropagation is carried out under
A. Natural conditions
B. Field conditions
C. Sterile conditions
D. Polluted conditions
Answer: C
The commonly used culture medium in micropropagation is
A. Knop’s medium
B. MS medium
C. Hoagland solution
D. White’s medium
Answer: B
MS medium was developed by
A. Murashige and Skoog
B. Watson and Crick
C. Haber and Bosch
D. Mendel
Answer: A
Which hormone promotes shoot formation?
A. Auxin
B. Gibberellin
C. Cytokinin
D. Abscisic acid
Answer: C
Which hormone promotes root formation?
A. Cytokinin
B. Auxin
C. Ethylene
D. ABA
Answer: B
The plant part used to initiate culture is called
A. Callus
B. Explant
C. Embryo
D. Protoplast
Answer: B
Apical meristem culture is mainly used to produce
A. Hybrid plants
B. Polyploid plants
C. Virus-free plants
D. Seedless plants
Answer: C
The first stage of micropropagation is
A. Multiplication
B. Rooting
C. Hardening
D. Establishment of culture
Answer: D
The stage involving rapid increase in shoot number is
A. Initiation
B. Multiplication
C. Rooting
D. Hardening
Answer: B
Root formation occurs during
A. Stage I
B. Stage II
C. Stage III
D. Stage IV
Answer: D
Hardening is also known as
A. Inoculation
B. Acclimatization
C. Sterilization
D. Differentiation
Answer: B
Hardening is necessary because in vitro plants
A. Are genetically weak
B. Lack chlorophyll
C. Are sensitive to external environment
D. Are diseased
Answer: C
Carbon source commonly used in culture medium is
A. Glucose
B. Fructose
C. Sucrose
D. Starch
Answer: C
Agar is used in culture medium as
A. Nutrient
B. Growth regulator
C. Gelling agent
D. Vitamin
Answer: C
Which crop is commercially micropropagated in India?
A. Wheat
B. Banana
C. Maize
D. Barley
Answer: B
Somatic embryogenesis involves formation of embryos from
A. Zygote
B. Gametes
C. Somatic cells
D. Pollen grains
Answer: C
Callus is
A. Organized tissue
B. Unorganized mass of cells
C. Meristematic tissue
D. Vascular tissue
Answer: B
Somaclonal variation refers to
A. Genetic uniformity
B. Genetic variation among tissue culture plants
C. Seed dormancy
D. Hybridization
Answer: B
Which of the following is an advantage of micropropagation?
A. Seasonal production
B. Slow multiplication
C. Disease-free plants
D. Genetic variability
Answer: C
One major limitation of micropropagation is
A. Low multiplication rate
B. High cost
C. Lack of nutrients
D. Poor growth
Answer: B
Which sterilant is commonly used for explant surface sterilization?
A. Phenol
B. Ethanol
C. Benzene
D. Ether
Answer: B
Micropropagation produces plants that are
A. Genetically different
B. Genetically identical
C. Sterile
D. Polyploid
Answer: B
The technique is most useful for propagation of
A. Annual crops
B. Biennial crops
C. Elite varieties
D. Weeds
Answer: C
Which structure is least used as explant?
A. Meristem
B. Leaf
C. Root tip
D. Seed coat
Answer: D
The temperature for most tissue culture labs is around
A. 5°C
B. 15°C
C. 25°C
D. 40°C
Answer: C
Light requirement during culture is generally
A. Complete darkness
B. High sunlight
C. Controlled photoperiod
D. UV radiation
Answer: C
Which crop is propagated through micropropagation to avoid viral diseases?
A. Rice
B. Banana
C. Wheat
D. Sorghum
Answer: B
In micropropagation, repeated transfer to fresh medium is called
A. Hardening
B. Subculturing
C. Sterilization
D. Differentiation
Answer: B
Which plant growth regulator combination induces callus formation?
A. High cytokinin
B. High auxin
C. Auxin + cytokinin
D. Gibberellin alone
Answer: C
The main objective of large-scale micropropagation is
A. Genetic variation
B. Rapid clonal multiplication
C. Hybrid seed production
D. Mutation breeding
Answer: B
Which structure is most suitable for true-to-type plants?
A. Leaf explant
B. Root explant
C. Meristem
D. Callus
Answer: C
Which of the following is NOT an application of micropropagation?
A. Germplasm conservation
B. Rapid multiplication
C. Virus elimination
D. Crop rotation
Answer: D
Which nutrient is required in large quantity in MS medium?
A. Iron
B. Zinc
C. Nitrogen
D. Copper
Answer: C
In vitro plants initially lack
A. Roots
B. Leaves
C. Cuticle and functional stomata
D. Vascular tissue
Answer: C
Which crop is commonly micropropagated using nodal explants?
A. Potato
B. Banana
C. Sugarcane
D. All of the above
Answer: D
Which stage ensures survival under field conditions?
A. Initiation
B. Multiplication
C. Rooting
D. Hardening
Answer: D
Cytokinins mainly promote
A. Root growth
B. Shoot proliferation
C. Senescence
D. Abscission
Answer: B
Micropropagation helps in conservation of
A. Weeds
B. Endangered plants
C. Pathogens
D. Insects
Answer: B
The nutrient medium must be
A. Acidic only
B. Alkaline only
C. Sterile
D. Dry
Answer: C
Which of the following is an ornamental plant produced by micropropagation?
A. Rice
B. Orchid
C. Wheat
D. Maize
Answer: B
Which factor does NOT affect micropropagation?
A. Light
B. Temperature
C. Humidity
D. Wind
Answer: D
A major economic benefit of micropropagation is
A. Increased seed size
B. Uniform yield
C. Genetic diversity
D. Delayed flowering
Answer: B
The success of micropropagation largely depends on
A. Soil type
B. Explant source
C. Rainfall
D. Wind speed
Answer: B
Which technique avoids seed dormancy problems?
A. Hybridization
B. Micropropagation
C. Mutation breeding
D. Polyploidy
Answer: B
Micropropagation is widely used in
A. Traditional farming
B. Organic composting
C. Commercial nurseries
D. Animal breeding
Answer: C
The final product of micropropagation is
A. Callus
B. Protoplast
C. Plantlet
D. Embryo sac
Answer: C
Micropropagation is an important tool of
A. Ecology
B. Biotechnology
C. Zoology
D. Geology
Answer: B




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