Skip to main content

Callus Culture and Regeneration of Plants


Callus Culture and Regeneration of Plants

Introduction


Callus culture is an in vitro plant tissue culture technique in which an unorganized mass of proliferating cells (callus) is induced from explants such as leaf, stem, root, or meristem under aseptic and controlled conditions. These callus cells retain totipotency, enabling regeneration of complete plants under suitable hormonal and nutritional conditions.
Callus culture forms the foundation of plant biotechnology, playing a crucial role in micropropagation, genetic transformation, somaclonal variation, and secondary metabolite production.

Definition


Callus is a mass of undifferentiated parenchymatous cells produced by continuous cell division of explant tissues when cultured on a nutrient medium supplemented with plant growth regulators.
Principle of Callus Culture
Based on the concept of cellular totipotency.
Dedifferentiation of mature cells occurs due to the action of auxins and cytokinins.
Redifferentiation and organ formation occur by altering the hormonal balance in the culture medium.


Explant Sources


Leaf segments
Stem nodes and internodes
Root tips
Hypocotyls
Cotyledons
Meristematic tissues

Culture Medium

The commonly used medium is Murashige and Skoog (MS) medium, containing:
Components
Macronutrients – N, P, K, Ca, Mg, S
Micronutrients – Fe, Mn, Zn, Cu, Mo
Vitamins – Thiamine, Nicotinic acid, Pyridoxine
Carbon source – Sucrose
Plant growth regulators
Auxins: 2,4-D, NAA, IAA
Cytokinins: BAP, Kinetin
Solidifying agent – Agar

Steps in Callus Culture


1. Selection of Explant

Healthy, young tissues with high meristematic activity are selected.

2. Surface Sterilization

Washing with detergent
Treatment with ethanol (70%)
Sterilization using sodium hypochlorite or mercuric chloride
Rinsing with sterile distilled water

3. Inoculation

Sterilized explants are placed aseptically on nutrient medium.

4. Incubation

Temperature: 25 ± 2°C
Photoperiod: Dark or low light
Relative humidity controlled

5. Callus Induction

High auxin concentration (especially 2,4-D) promotes callus formation.
Types of Callus
Compact callus – Hard, dense, slow growing
Friable callus – Soft, loose, fast growing
Embryogenic callus – Capable of forming somatic embryos
Non-embryogenic callus – Cannot regenerate plants
Plant Regeneration from Callus


Plant regeneration occurs through two main pathways:

1. Organogenesis
Formation of organs (shoots and roots) from callus.
Types
Direct organogenesis – Organs develop directly from explant
Indirect organogenesis – Organs develop via callus phase
Hormonal Control
High cytokinin : auxin → Shoot formation
High auxin : cytokinin → Root formation

2. Somatic Embryogenesis

Formation of embryo-like structures from somatic cells.
Stages
Globular stage
Heart-shaped stage
Torpedo stage
Cotyledonary stage
Somatic embryos germinate to form complete plantlets.
Hardening and Acclimatization
Regenerated plantlets are transferred to soil or vermiculite.
Gradual exposure to external environment.
Essential for survival under field conditions.


Factors Affecting Callus Culture
Type and age of explant
Composition of medium
Concentration of growth regulators
pH of medium (5.6–5.8)
Temperature and light
Genotype of plant
Applications of Callus Culture
Micropropagation of plants
Production of disease-free plants
Genetic transformation and transgenic plants
Somaclonal variation and crop improvement
Production of secondary metabolites
Germplasm conservation
Protoplast culture and fusion


Advantages
Rapid multiplication of plants
Year-round production
Requires small space
Useful for rare and endangered species

Limitations
Somaclonal variation
High cost and technical skill required
Risk of contamination
Not suitable for all plant species


Conclusion
Callus culture and plant regeneration represent a cornerstone of plant tissue culture technology. By manipulating growth regulators and culture conditions, whole plants can be regenerated from undifferentiated cells, demonstrating the totipotent nature of plant cells. This technique has immense significance in plant breeding, biotechnology, and conservation.



Callus is a mass of
A. Differentiated cells
B. Undifferentiated cells
C. Dead cells
D. Reproductive cells
Answer: B
Callus culture is based on the principle of
A. Differentiation
B. Totipotency
C. Mutation
D. Hybridization
Answer: B
The most suitable tissue for callus induction is
A. Xylem
B. Phloem
C. Meristematic tissue
D. Cork
Answer: C
The most widely used medium for callus culture is
A. White’s medium
B. Knop’s medium
C. Murashige and Skoog (MS) medium
D. Gamborg’s medium
Answer: C
Which hormone is essential for callus induction?
A. Cytokinin
B. Auxin
C. Gibberellin
D. Ethylene
Answer: B
2,4-D is a synthetic
A. Cytokinin
B. Auxin
C. Gibberellin
D. Inhibitor
Answer: B
High concentration of auxin promotes
A. Shoot formation
B. Root formation
C. Callus formation
D. Flower formation
Answer: C
Friable callus is
A. Hard and compact
B. Soft and loosely arranged
C. Highly differentiated
D. Dead tissue
Answer: B
Compact callus is
A. Loose and soft
B. Hard and dense
C. Embryogenic
D. Liquid
Answer: B
Embryogenic callus is capable of
A. Rooting only
B. Shoot formation only
C. Somatic embryogenesis
D. Senescence
Answer: C
Somatic embryogenesis originates from
A. Zygote
B. Somatic cells
C. Gametes
D. Pollen grains
Answer: B
The first stage of somatic embryo development is
A. Heart stage
B. Torpedo stage
C. Globular stage
D. Cotyledonary stage
Answer: C
Organogenesis is the formation of
A. Seeds
B. Callus
C. Organs
D. Protoplasts
Answer: C
Organ formation through callus is called
A. Direct organogenesis
B. Indirect organogenesis
C. Micropropagation
D. Fertilization
Answer: B
High cytokinin to auxin ratio induces
A. Roots
B. Shoots
C. Callus
D. Embryos
Answer: B
High auxin to cytokinin ratio induces
A. Shoots
B. Roots
C. Leaves
D. Flowers
Answer: B
Agar in culture media functions as
A. Nutrient
B. Growth regulator
C. Solidifying agent
D. Vitamin
Answer: C
Sucrose acts as a
A. Hormone
B. Vitamin
C. Carbon source
D. Buffer
Answer: C
The optimal pH of MS medium is
A. 3.5
B. 4.5
C. 5.6–5.8
D. 7.0
Answer: C
Ideal temperature for callus culture is
A. 15°C
B. 20°C
C. 25 ± 2°C
D. 35°C
Answer: C
Surface sterilization is done to avoid
A. Differentiation
B. Growth
C. Contamination
D. Regeneration
Answer: C
Mercuric chloride is used for
A. Nutrition
B. Sterilization
C. Hormone action
D. Solidification
Answer: B
Callus culture requires
A. Open field conditions
B. Aseptic conditions
C. Natural soil
D. Sunlight only
Answer: B
Totipotency refers to the ability of a cell to
A. Divide only
B. Form callus
C. Develop into a whole plant
D. Form roots only
Answer: C
Thiamine added in MS medium is a
A. Hormone
B. Vitamin
C. Carbohydrate
D. Enzyme
Answer: B
Non-embryogenic callus
A. Produces embryos
B. Regenerates plants
C. Cannot regenerate plants
D. Is highly organized
Answer: C
Callus culture is widely used in
A. Animal breeding
B. Plant biotechnology
C. Marine biology
D. Zoology
Answer: B
Genetic variation arising in tissue culture is called
A. Mutation
B. Hybridization
C. Somaclonal variation
D. Polyploidy
Answer: C
Which of the following is a cytokinin?
A. IAA
B. NAA
C. BAP
D. 2,4-D
Answer: C
Callus culture is useful for production of
A. Antibiotics
B. Secondary metabolites
C. Vaccines
D. Hormones
Answer: B
Hardening of plantlets is done to
A. Increase growth
B. Increase callus
C. Acclimatize plants to external conditions
D. Induce mutation
Answer: C
Callus cells are usually
A. Dead
B. Non-dividing
C. Actively dividing
D. Specialized
Answer: C
Callus induction generally requires
A. Bright light
B. Continuous light
C. Darkness or low light
D. UV light
Answer: C
Best explant for regeneration is
A. Old tissue
B. Mature tissue
C. Young meristem
D. Dead tissue
Answer: C
Plant regeneration from callus proves
A. Mutation
B. Totipotency
C. Heterosis
D. Polyploidy
Answer: B
Callus culture is a technique of
A. Ecology
B. Cytology
C. Plant tissue culture
D. Taxonomy
Answer: C
Somatic embryos differ from zygotic embryos because they
A. Undergo fertilization
B. Lack dormancy
C. Contain endosperm
D. Form seeds
Answer: B
Gibberellins mainly promote
A. Callus formation
B. Stem elongation
C. Rooting
D. Senescence
Answer: B
MS medium was developed by
A. White
B. Knop
C. Murashige and Skoog
D. Gamborg
Answer: C
Structure that develops into a complete plant in somatic embryogenesis is
A. Root primordium
B. Shoot primordium
C. Somatic embryo
D. Callus mass
Answer: C
Callus culture is useful for
A. Micropropagation
B. Genetic transformation
C. Virus-free plants
D. All of the above
Answer: D
Which factor does NOT affect callus culture?
A. Genotype
B. Medium composition
C. Growth regulators
D. Soil type
Answer: D
Protoplast culture is often initiated from
A. Seeds
B. Callus
C. Flowers
D. Fruits
Answer: B
Callus formation represents
A. Redifferentiation
B. Dedifferentiation
C. Fertilization
D. Senescence
Answer: B
Redifferentiation results in
A. Callus formation
B. Organ formation
C. Cell death
D. Variation
Answer: B
Secondary metabolites are commonly produced using
A. Seed culture
B. Root culture
C. Callus culture
D. Pollen culture
Answer: C
Balanced auxin and cytokinin concentrations favor
A. Rooting
B. Shooting
C. Callus induction
D. Flowering
Answer: C
Plant tissue culture requires
A. Sterile environment
B. Soil
C. Rainwater
D. Fertilizers
Answer: A
Callus culture is helpful in conservation of
A. Common plants
B. Rare plants
C. Endangered plants
D. Both B and C
Answer: D
The final goal of callus culture is
A. Callus formation
B. Cell multiplication
C. Whole plant regeneration
D. Mutation induction
Answer: C



Labels:

Comments

Post a Comment

Popular Posts

••CLASSIFICATION OF ALGAE - FRITSCH

      MODULE -1       PHYCOLOGY  CLASSIFICATION OF ALGAE - FRITSCH  ❖F.E. Fritsch (1935, 1945) in his book“The Structure and  Reproduction of the Algae”proposed a system of classification of  algae. He treated algae giving rank of division and divided it into 11  classes. His classification of algae is mainly based upon characters of  pigments, flagella and reserve food material.     Classification of Fritsch was based on the following criteria o Pigmentation. o Types of flagella  o Assimilatory products  o Thallus structure  o Method of reproduction          Fritsch divided algae into the following 11 classes  1. Chlorophyceae  2. Xanthophyceae  3. Chrysophyceae  4. Bacillariophyceae  5. Cryptophyceae  6. Dinophyceae  7. Chloromonadineae  8. Euglenineae    9. Phaeophyceae  10. Rhodophyceae  11. Myxophyce...
Post a Comment
Read more

Mapping of DNA

DNA MAPPING   1. Introduction DNA mapping refers to the process of determining the relative positions of genes or DNA sequences on a chromosome. It provides information about the organization, structure, and distance between genetic markers in a genome. DNA mapping is an essential step toward genome sequencing, gene identification, disease diagnosis, and genetic engineering. DNA maps serve as roadmaps that guide researchers to locate specific genes associated with traits or diseases. 2. Objectives of DNA Mapping To locate genes on chromosomes To determine the order of genes To estimate distances between genes or markers To study genome organization To assist in genome sequencing projects. 3. Principles of DNA Mapping DNA mapping is based on: Recombination frequency Physical distance between DNA fragments Hybridization of complementary DNA Restriction enzyme digestion Use of genetic markers The closer two genes are, the less frequently they recombine during meiosis. 4 . Types of DNA...
2 comments
Read more

Biological Databases – Types of Data and DatabasesNucleotide Sequence Databases (EMBL, GenBank, DDBJ)

Biological Databases – Types of Data and Databases Nucleotide Sequence Databases (EMBL, GenBank, DDBJ) 1. Introduction Biological databases are systematic, computerized collections of biological information that allow efficient storage, retrieval, updating, and analysis of large volumes of biological data. With the advent of genome sequencing, molecular biology, and bioinformatics, biological databases have become essential tools in biological research. These databases support studies in genomics, proteomics, evolutionary biology, taxonomy, medicine, agriculture, and biotechnology. 2. Types of Data Stored in Biological Databases Biological databases store diverse types of biological information, including: 1. Sequence Data DNA sequences RNA sequences Protein sequences 2. Structural Data Three-dimensional structures of proteins Nucleic acid structures 3. Functional Data Gene functions Enzyme activity Regulatory elements 4. Genomic Annotation Data Gene location Exons, introns Promoters a...
Post a Comment
Read more

Agrobacterium & CaMV-Mediated Gene Transfer –

Agrobacterium and CaMV-Mediated Gene Transfer – Detailed Notes 1. Introduction Gene transfer in plants is often achieved by exploiting natural genetic mechanisms of Agrobacterium tumefaciens and Cauliflower Mosaic Virus (CaMV). These systems allow stable introduction of foreign genes into plant genomes for transgenic plant development. 2. Agrobacterium-Mediated Gene Transfer 2.1 Definition Agrobacterium-mediated gene transfer uses the natural ability of Agrobacterium tumefaciens, a soil bacterium, to transfer a part of its DNA (T-DNA) into plant cells. T-DNA integrates into the plant nuclear genome, enabling stable transformation. 2.2 Mechanism Recognition and attachment Agrobacterium detects phenolic compounds secreted by wounded plant cells. These compounds activate virulence (vir) genes on the Ti (tumor-inducing) plasmid. Activation of vir genes VirA (sensor kinase) and VirG (response regulator) induce expression of other vir genes (VirB, VirC, VirD, VirE). T-DNA processing and tran...
Post a Comment
Read more

❃HPLC – High Performance Liquid Chromatography

HPLC – High Performance Liquid Chromatography ┏━━━━━ •❃°•°❀°•°❃•━━━━•━━━┓  1. Introduction High Performance Liquid Chromatography (HPLC) is an advanced analytical technique used for the separation, identification, and quantification of components present in a mixture. It is based on the differential distribution of analytes between a stationary phase and a liquid mobile phase under high pressure. HPLC is widely used in biochemistry, biotechnology, pharmaceuticals, food analysis, environmental studies, and clinical diagnostics. 2. Principle of HPLC The principle of HPLC is based on partition, adsorption, ion-exchange, or size-exclusion mechanisms, depending on the type of column used. A liquid mobile phase is pumped at high pressure through a column packed with fine stationary phase particles Sample components interact differently with the stationary phase Components with stronger interaction elute slower Components with weaker interaction elute faster Separated components are detec...
Post a Comment
Read more

❃HPTLC (HIGH PERFORMANCE THIN LAYER CHROMATOGRAPHY) DETAILED NOTES

HPTLC (HIGH PERFORMANCE THIN LAYER CHROMATOGRAPHY) DETAILED NOTES ┏━━━━━ •❃°•°❀°•°❃•━━━━•━━━┓ 1. INTRODUCTION HPTLC is an advanced form of Thin Layer Chromatography (TLC) that allows high-resolution separation and quantitative analysis of chemical compounds. It combines classical TLC principles with automation, precise sample application, and densitometric detection. HPTLC is widely used in pharmaceuticals, herbal medicine, food analysis, and chemical research. Compared to TLC, HPTLC offers: Better resolution Higher sensitivity Quantitative capabilities Example: Fingerprinting of plant extracts, identification of drugs in mixtures, detection of contaminants in food. 2. PRINCIPLE HPTLC separates compounds based on differential migration on a stationary phase under the influence of a mobile phase. Principle: Adsorption chromatography Compounds interact with the stationary phase (silica gel, alumina, or cellulose) differently depending on polarity, molecular size, or functional groups. Mo...
Post a Comment
Read more

❃LC-MS (LIQUID CHROMATOGRAPHY – MASS SPECTROMETRY)

LC-MS (LIQUID CHROMATOGRAPHY – MASS SPECTROMETRY)  ┏━━━━━ •❃°•°❀°•°❃•━━━━•━━━┓ 1. INTRODUCTION LC-MS is a hyphenated analytical technique combining Liquid Chromatography (LC) and Mass Spectrometry (MS). It is used for separation, identification, and quantification of compounds in complex mixtures. LC separates analytes based on polarity, size, or charge, while MS detects molecules based on mass-to-charge ratio (m/z). Developed in the 1970s–1980s, LC-MS is now widely used in pharmaceutical, clinical, environmental, and food analysis. Importance : Detects trace levels of compounds (ng–pg range) Analyzes non-volatile, thermally labile compounds that cannot be analyzed by GC-MS Provides structural information through mass fragmentation Example: Detection of drugs in plasma, protein identification in proteomics, pesticide residue analysis in food. 2. COMPONENTS OF LC-MS The LC-MS system has three main parts: A. Liquid Chromatograph (LC) Function: Separates components of a mixture befor...
Post a Comment
Read more