Question

What is tissue culture? Describe the methodology of tissue culture.

Answer 1

Hint: This process is of great significance as it may be used for cloning purposes, genetic modification of a given plant, or simply to accelerate or increase the yield of the plant of interest.

Complete answer:
Tissue culture is the growth of tissues or cells in an artificial medium outside the parent organism under sterile conditions. The media can be liquid, semi-solid, or solid growth media containing broth or agar. It is widely used to produce clones of a plant in a method known as micropropagation.

The advantages of tissue culture are-
- To produce large quantities of a given plant.
- To accelerate the production of new varieties of a plant.
- To eliminate the presence of any pest or virus from the plant of interest.

The methodology of plant tissue culture involves the following steps:
- Initiation Phase- It is the first phase of tissue culture. Here, the tissue of interest (expand) is obtained and introduced and sterilized in order to prevent any microorganism from negatively affecting the process. It is during this stage that the tissue is initiated into the culture.
- Multiplication Phase- It is the second step of tissue culture where the in vitro plant material is redivided and then introduced into the medium. The medium is composed of different components required for the growth including regulators and nutrients. These are responsible for the proliferation of the tissue and the production of multiple shoots.
- Root formation- It is at this phase that roots are formed. Here, hormones are required in order to induce rooting, and consequently complete plantlets.

Note:
- Micropropagation- It is a technique of developing high yielding clonal plants (a clone is a group of identical cells). This has the potential to provide rapid and large scale propagation of new genotypes.
- The nutrient media consists of auxin, cytokinin, hydrochloric acid, sodium hydroxide, and agar. The explant turns into callus which is a mass of undifferentiated cells. Callus when treated with auxin promotes rooting and when it is treated with cytokinin it stimulates cell maturation, differentiation. HCl and NaOH maintain the pH of the media. After the formation of the stem, it differentiates into a mature plant.