Meristem is a localised group of cells, which are actively dividing and undifferentiated but ultimately give rise to permanent tissue. They are mostly present at the tip or apex of shoots and roots.

So Correct Ans: A

Meristem culture is the culture of axillary or apical shoot meristems. Meristems are regions of actively dividing cells in plants that give rise to new cells and tissues. They are responsible for the growth and development of plants. Meristem culture is a technique used in plant tissue culture to propagate plants asexually.

- Definition:
Meristem culture involves the isolation and cultivation of the shoot meristems from plants. This technique allows for the production of multiple identical plants through the process of micropropagation.

- Axillary or Apical Shoot Meristems:
Axillary meristems are found in the axils of leaves, while apical meristems are located at the tips of stems and roots. These meristems contain undifferentiated cells that have the ability to differentiate into various plant tissues.

- Isolation of Meristems:
To initiate meristem culture, axillary or apical shoot meristems are carefully excised from the donor plant. The meristems are typically small and require skilled hands to isolate them without contamination.

- Sterilization:
After isolation, the meristems are surface sterilized to eliminate any potential contaminants such as bacteria or fungi. This is done by treating them with a sterilizing agent such as bleach or alcohol.

- Culture Medium:
The isolated meristems are then placed onto a culture medium that contains all the necessary nutrients and growth regulators for their growth and development. The medium is usually a gel-like substance, such as agar, which provides support for the meristems.

- Shoot Proliferation:
Under controlled conditions, the meristems start to divide and produce multiple shoots. This process is known as shoot proliferation. The shoots can be further subcultured to increase their numbers.

- Rooting:
Once an adequate number of shoots have been produced, they can be transferred to a rooting medium. This medium contains growth regulators that promote root development. The rooted plantlets can then be transferred to soil for further growth.

Meristem culture is a valuable technique in plant propagation as it allows for the rapid production of large numbers of genetically identical plants. It is commonly used in the commercial production of ornamental plants, fruit trees, and other crops. Additionally, meristem culture can be used for the conservation of rare or endangered plant species.