Plant Tissue Culture Techniques

Introduction

• Plant tissue culture, also known as micropropagation, is a technique used to cultivate plant cells, tissues, or organs in a sterile environment.
• The goal is to generate a large number of genetically identical plants (clones) from a small explant specimen.
• This technique is widely used in horticulture, agriculture, and research.

Key Principles

• Aseptic technique and sterile media are essential for successful plant culture.
• Growing media is commonly formulated from agar, sugar, vitamins, and plant growth regulators.
• Plant growth regulators such as auxins and cytokinins are crucial in inducing specific developmental processes.
• The culture medium provides the necessary nutrients, minerals, and hormones for growth and development.

Explant selection

• The explant is the initial piece of plant material used for tissue culture.
• Various explant types can be used, including leaf segments, shoot tips, meristems, root segments, and embryos.
• Important considerations include proper sterilization to prevent contamination and selecting explant material with high regenerative capacity.

Culture establishment

• The explant material is placed on a sterilized growth medium and incubated under controlled conditions (temperature, light, humidity) that facilitates callus formation and multiplication.
• Appropriate growth regulators are often added to induce desired morphogenic processes.
• Monitoring for signs of contamination, callus formation, shoot development, and root formation is essential.

Callus induction

• Callus is a mass of undifferentiated cells, which forms when the explant is placed on specific culture media.
• Different media and growth regulators trigger different types of callus development.

Shoot multiplication

• After callus formation, specific growth regulators can promote the development of shoots from the callus.
• Multiple shoots can often be generated from a single callus forming a cluster of shoots.
• This process can increase the number of plantlets significantly.

Root formation

• After shoot formation, roots can develop on the shoots when cultured under suitable conditions.
• The growth regulators in the medium can influence the development of the root system.
• The roots are necessary for proper plant establishment.

Acclimatization

• Once the shoots have developed roots, the plantlets are often transferred to a potting medium.
• This process is called acclimatization.
• The controlled transition to a higher humidity environment and gradual exposure to normal light and conditions allows the plants to adjust to their new surroundings.

Applications

• Clonal propagation of superior plants with desirable traits
• Rapid propagation of endangered plant species
• Production of disease-free plants
• Production of plant variants with increased yield, herbicide tolerance, etc.
• Producing valuable secondary metabolites

Advantages

• Production of thousands of genetically identical plants
• Fast propagation in comparison to traditional methods
• Preservation and multiplication of valuable genotypes
• Production of disease-free plants
• Reduced space requirements compared to traditional methods

Disadvantages

• Expensive instrumentation and sterilization required
• Labour intensive in comparison to many traditional practices
• Potential for contamination
• The technique is not suitable for all plant species
• Time-consuming establishment and multiplication process

Potential Issues

• Contamination by microorganisms (bacteria, fungi, viruses)
• Medium deficiencies or improper pH values
• Plant growth regulator imbalances
• Improper environmental conditions (temperature, light, humidity)
• Incorrect acclimatization procedures.