Callus

Definition

A callus is a mass of undifferentiated plant cells that forms at the site of injury or during tissue culture processes. This cellular mass has the unique ability to develop into various types of plant tissues, making it essential for regeneration and propagation in plant tissue culture and micropropagation techniques. Callus formation is a crucial step in producing new plants from small tissue samples, enabling efficient plant breeding and conservation efforts.

5 Must Know Facts For Your Next Test

1. Callus can be induced on various plant tissues, including leaf segments, stem pieces, or even single cells, when exposed to specific culture conditions.
2. The composition of the culture medium, including the presence of nutrients and plant growth regulators, greatly affects the rate and quality of callus formation.
3. Callus can be either organized or unorganized; organized callus can differentiate into roots or shoots, while unorganized callus remains as a mass of undifferentiated cells.
4. In micropropagation, callus plays a vital role in generating multiple identical plants from a single tissue sample, enhancing propagation efficiency.
5. Callus can also be used for genetic transformation experiments, where foreign DNA can be introduced into the callus cells to create genetically modified plants.

Review Questions

• How does the formation of callus contribute to the process of plant regeneration and micropropagation?
  • The formation of callus is a critical step in plant regeneration and micropropagation because it serves as a source of undifferentiated cells that can develop into various types of tissues. By inducing callus formation from small tissue samples, researchers can encourage these cells to either differentiate into roots or shoots or remain as a mass for further manipulation. This process allows for the efficient production of multiple identical plants, which is essential in agriculture and horticulture.
• Discuss the factors that influence callus induction in plant tissue culture and their implications for successful micropropagation.
  • Several factors influence callus induction in plant tissue culture, including the type of explant used, the composition of the culture medium, and the presence of plant growth regulators. For instance, specific ratios of auxins and cytokinins can promote cell division and differentiation. Understanding these factors is crucial because optimizing them can lead to successful micropropagation by increasing the quantity and quality of the callus formed, ultimately affecting the overall success rate of regenerating new plants.
• Evaluate the role of callus in genetic transformation techniques in plants and its potential impact on agricultural biotechnology.
  • Callus plays a significant role in genetic transformation techniques because it serves as a target tissue where foreign DNA can be introduced. Techniques such as Agrobacterium-mediated transformation utilize callus cells to incorporate new genetic material, allowing researchers to develop genetically modified plants with desirable traits. This capability has profound implications for agricultural biotechnology as it enables the creation of crops with enhanced resistance to pests, diseases, or environmental stresses, contributing to food security and sustainable agriculture.

Related terms

Totipotency: The ability of a single plant cell to divide and develop into a whole plant, including roots, stems, and leaves.

Agar: A gel-like substance derived from algae used as a solidifying agent in culture media for growing plant tissues.

Plant Growth Regulators (PGRs): Chemical substances that influence plant growth and development, playing a key role in callus formation and differentiation during tissue culture.