Organogenesis is the process by which plant cells
develop into organs such as roots, shoots, or leaves. This process is a key
step in tissue culture, where it is used to regenerate whole plants from small
pieces of plant tissue. Organogenesis can be initiated from different types of
plant tissues such as stem, leaf, root or shoot meristems.
The process of organogenesis can be divided into several
stages:
- Callus
induction: To initiate organogenesis, plant tissue is first cultured on a
nutrient medium containing plant growth regulators such as auxins and
cytokinins. These hormones stimulate the formation of a mass of
undifferentiated cells known as a callus. The callus serves as a source of
cells for further organogenesis.
- Shoot
initiation: Once the callus has formed, it can be transferred to a medium
containing a high concentration of cytokinins, which promotes shoot
initiation. The cytokinins stimulate the formation of small protuberances
from the callus, which later develop into shoots.
- Shoot
elongation: The shoots are then transferred to a medium containing lower
concentrations of cytokinins and higher concentrations of auxins. This
helps to elongate the shoots and promote the formation of leaves.
- Root
induction: Once the shoots have grown to a certain size, they can be
transferred to a medium containing auxins, which promotes the formation of
roots. This process is called root induction.
- Acclimatization:
Once the roots have formed, the plantlets can be transferred to soil and
grown in a greenhouse or field. The plantlets need to be gradually
acclimatized to the external environment before they can be planted in the
field.
Organogenesis is a versatile technique that can be used to
regenerate whole plants from a wide range of plant tissues. The process can be
optimized by varying the concentrations of plant growth regulators and other
nutrients in the culture medium. However, the success of organogenesis can be
influenced by factors such as the genotype of the plant, the type of tissue used,
and the culture conditions used. With proper optimization, organogenesis can be
used to produce large numbers of healthy plants with desirable traits.