Tissue Culture: Definition, Types, Steps, Examples, Diagram, Techniques

What is Tissue Culture?

It is a refined biological technique used in growing and maintaining cells, tissues, or organs outside their natural environment, usually in a controlled laboratory atmosphere. In this method, a small portion of tissue, known as an explant, is taken from a plant, animal, or microbial source. The explant is transferred into a sterile state in a nutrient rich medium. The culture medium contains all the necessary nutrients, growth factors, and hormones to be used in conditions that promote optimum growth and development.

It is done by creating a controlled environment in tissue culture, which would provide the optimum setting for cell proliferation and differentiation. The researchers thereby carry on studies of cellular behaviour, conduct genetic manipulations, and grow large amounts of uniform cells or tissues that are used in various applications. Tissue culture assumes a central role in joining many advances in biotechnological, medical, agricultural, and environmental conservation domains through studies relating to complex biological activities or improvements in agriculture and therapeutic new remedies.

Types of Tissue Culture

Tissue culture techniques can vary depending on the part of the plant used and the purpose of the culture. These types allow scientists to grow and maintain cells in controlled environments. Each method has specific conditions and applications. The types of tissue culture can be broadly categorised into:

Organ Culture

Organ culture is when intact organs or parts of organs are grown under controlled conditions outside the body of an organism. The technique helps in maintaining the structural and functional properties of organs so that researchers can further elucidate growth, development, and responses to different stimuli. Organ cultures are used by investigators dealing with plants and animals. Plant organ cultures are applied to study development of the root system, flowering patterns, and responses to various environmental stresses. Organ cultures in animals contribute to biomedical research by studying functions of organs, mechanisms of various diseases, and treatments.

Cell Culture

Cell culture is concerned with the isolation and in vitro growth of single cells or small groups of cells. It is one of the most frequently employed techniques not only throughout biomedical sciences but also in the development of pharmaceuticals and genetic engineering. Cell cultures may be derived from animal tissues, plant tissues, or microbial cultures. They are used to study cellular behaviours like proliferation, differentiation, metabolism, response to drugs or toxins, etc. Tissue culture techniques have become an essential tool in the generation of cell lines, assessment of toxicity tests, and development of therapies against various diseases.

Plant Tissue Culture

Plant tissue culture has a variety of techniques which are oriented towards the propagation and manipulation of plant cells, tissues, or organs in an aseptic environment. It finds extensive applications in agriculture and horticulture for the mass production of disease-free plants, effective multiplication of elite cultivars, and conservation of endangered species. Applications in this field are mostly attributed to micropropagation, somatic embryogenesis, and genetic transformation. Through the tissue culture techniques, such as the development of genetically modified crops that have increased resistance to several pests, diseases and environmental stresses, plant tissue culture has completely revolutionised agricultural practice.

Animal Tissue Culture

Animal tissue culture is cultivated in a laboratory for research study purposes, testing of pharmaceutical compounds, and medical uses. This forms a very prominent area in understanding cellular physiology, mechanisms of various diseases, and drug responses in the controlled environment of a laboratory. Animal tissue cultures have applications in the development of cell-based assays, the production of vaccines and therapeutic proteins, and the modelling of human diseases in drug discovery and biomedical research. Primary isolation of cells directly from tissues and immortalised cells, otherwise cell lines, are some of the techniques applied in studying a complex biological process and developing novel treatments.

Microbial Culture

Microbial culture is the process of growing and maintaining microorganisms such as bacteria, fungi, algae, etc., in laboratory conditions. It is very important in studies on microbial physiology, genetics, and biochemical pathways. Cultures find application in aspects connected with biotechnology, the production of food, and the control of the environment. They also turn out to be very useful tools in producing antibiotics, enzymes, and biofuels through microbial fermentation processes.

Steps of Tissue Culture

The process involves a sequence of steps to ensure successful growth. These steps must be performed in sterile conditions to avoid contamination. Growth media and controlled conditions are essential at each stage. Proper care is required throughout the process.The steps involved in the process of tissue culture are:

Explants and Preparation

• Type of Explants Used: Standard explants include apical meristem, embryos, and callus tissues. Each type is applied for certain purposes of tissue culture, like rapid proliferation or genetic transformation.

• Techniques of Preparation: These involve surface sterilisation, cutting, and precise dissection so that the explants are properly rid of contaminants, and ready to set in for culture.

Culture Media

• Media Composition: Culture media are composed of some of the basic requirements or nutrients, which involve macro and micronutrients, vitamins, amino acids, and growth regulators like auxins and cytokinins. All these components are added in a balanced way for the cells to grow and differentiate.

• Preparation and Sterilisation Methods: Media is prepared by mixing ingredients under sterile conditions. Sterilisation consists of passing media through a filter or autoclaving. This helps to avoid any kind of microbial contamination.

Culture Conditions

• Environmental Control: The temperature, humidity, pH, and CO2 are optimised for successful tissue culture. This supposedly provides the most analogous environment that cells require to proliferate and differentiate.

• Incubation and Maintenance: Cultures are incubated in a controlled environment, like growth chambers or bioreactors, where the growth of the cells will proceed and their progress with time is to be traced.

Importance of Plant Tissue Culture

Tissue culture spans disciplines such as biology, agriculture, and medicine because of its ability to grow cells and tissues in a controlled environment outside their natural context. In agricultural practices, it provides large-scale production of disease-free plants and propagation of plants that are facing extinction or are genetically altered to have new characteristics. Hence, advancing agricultural productivity and sustainability initiatives.

The importance of plant tissue culture has been a large tool in medicine in studying the mechanisms of many diseases, responses to drugs, and tissue regeneration. This creates the ability needed for the production of cell lines and three-dimensional tissue models, advancing biomedical research into innovations in personalised medicine and pharmaceutical development. Apart from that, tissue culture plays a very vital role in improving food security, understanding human health, and driving forward scientific discovery.

Applications of Tissue Culture

Tissue culture is widely used in agriculture, horticulture, and scientific research. It helps in rapid plant multiplication and conservation of endangered biodiversity. It also supports genetic studies and the development of disease-free plants. Tissue culture and its applications are described below-

• Micropropagation: It can produce numerous identical plants or clones rapidly for crops with desirable traits, for example resistance to certain diseases, high yield, etc. Tissue culture can also yield plants produced from disease-free meristematic tissues.

• Conservation of Rare and Endangered Plants: Tissue culture conserves plant species, whether they are rare, endangered, or difficult to propagate with seeds, by manufacturing multiple plants in a controlled environment.

• Genetic Modification and Research: One of the other uses of tissue culture is that it enables scientists to make genetic manipulations in the plant cells, thus developing genetically modified plants rich in certain desirable traits, like resistance to pests or increased nutrition.

Advantages and Disadvantages of Tissue Culture

This technique has many benefits, including fast propagation and uniform quality. However, it also comes with limitations like high cost and the need for technical expertise. Both strengths and challenges exist in this method.The advantages and disadvantages of tissue culture are listed below-

Merits of Tissue Culture

Tissue culture allows swift and efficient propagation of plants and cells from a limited population. Thus creating an opportunity for mass production of disease-free plants and contributing to the conservation of rare species. This can facilitate genetic variations to develop crops with desirable traits, thus enhancing agricultural productivity and fertility. It reduces the risk of contamination under aseptic conditions, hence guaranteeing predictable results for experiments.

Challenges and Limitations

It is expensive in terms of special apparatuses and artificial media, the mastery of which requires handling delicate tissues. Despite strict handling, there is a risk of contamination, which can be very frustrating and decrease experimental reliability. A lack of access to resources and technical skills to a large extent may limit its applications, especially in developing regions or smaller research facilities.

MCQs on Tissue Culture

Q1. What is the advantage of producing somaclones through tissue culture?

1. The ability to produce plants with desirable characteristics

2. The production of plants that are genetically identical to the original plant

3. The ability to recover healthy plants from diseased plants

4. The production of hybrid plants with desirable traits

Correct answer: 2) The production of plants that are genetically identical to the original plant

Explanation:

Somaclones produced through tissue culture are genetically identical to the original plant from which they were grown. This allows for the production of large numbers of plants with desirable characteristics, such as disease resistance or increased yield.

Hence, the correct answer is option 2) The production of plants that are genetically identical to the original plant.

Q2. What is the primary advantage of micropropagation in tissue culture?

1. It allows for the production of genetically modified plants.

2. It enables the rapid propagation of a large number of plants.

3. It facilitates the introduction of foreign DNA into plant cells.

4. It improves the nutritional quality of the cultured plants.

Correct answer: 2) It enables the rapid propagation of a large number of plants.

Explanation:

The primary benefit of employing micropropagation via tissue culture in the botanical context is its capability to generate a substantial quantity of clonal, genetically homogeneous plants within a brief temporal frame, originating from a minute segment of plant tissue. This technique's salient advantages include:

1. Mass Propagation: It enables the swift and extensive production of flora on a grand scale, which is particularly beneficial in agriculture and horticulture.
2. Disease-Free Plants: The utilization of meristematic tissue allows for the creation of pathogen-free specimens, which is crucial for maintaining plant health and productivity.
3. Uniformity: As all the plants produced are genetic replicas of the parent, this ensures a consistent expression of desirable traits among them.
4. Conservation: Micropropagation plays a vital role in the preservation and propagation of rare or threatened species, contributing significantly to biodiversity conservation efforts.
5. Year-Round Production: It circumvents the limitations imposed by seasonal and environmental factors, thus facilitating continuous cultivation throughout the year.

These distinctive features render micropropagation an excellent choice for applications in agriculture, horticulture, and environmental conservation domains.

Hence, the correct answer is option 2) It enables the rapid propagation of a large number of plants.

Q3. To obtain virus-free healthy plants from a diseased one by tissue culture technique, which part/parts of the diseased plant will be taken?

1. Apical meristem only

2. Palisade parenchyma

3. Both apical and axillary meristems

4. Epidermis only

Correct answer: 3) Both apical and axillary meristems.

Explanation:

Both apical and axillary meristems are free of virus for healthy plant cultivation because of strong interferon activity in this region. These tissues form a protective impermeable covering around themselves, which is non-penetrable by any pathogen. Therefore, these tissues are used in the production of disease-free plants by tissue culture.

Hence, the correct answer is option 3) Both apical and axillary meristems.

Also Read:

• MCQs on Tissue Culture and Somatic Hybridisation

• Animal Husbandry

• Single Cell Protein

Frequently Asked Questions (FAQs)

Q1. What is tissue culture?
Tissue culture is the technique of growing plant or animal cells in a nutrient medium under sterile conditions.

Q2. What are the three types of tissue culture?
The three main types are organ culture, cell culture, and callus culture.

Q3. What are the applications of tissue culture?
It is used in cloning, crop improvement, conservation of rare plants, and production of disease-free plants.

Q4. Who is the father of tissue culture?
Gottlieb Haberlandt is known as the father of tissue culture.

Q5. What are the principles of tissue culture?
It is based on the principle of totipotency, aseptic conditions, and the use of suitable growth media.