Differentiation, Dedifferentiation and Redifferentiation: The three phases of cellular growth are cell division, cell enlargement and cell differentiation, which bring maturity to the cells. The living differentiated cells, that have lost the capacity to divide can regain the power of division under certain conditions, this phenomenon is termed de-differentiation.

Meristems/tissues are able to divide and produce cells that once again lose the capacity to divide but mature to perform specific functions, i.e., get redifferentiated. Thus redifferentiation can be defined as maturation or differentiation of dedifferentiated tissues. Let us take a deeper look into the concept of differentiation, dedifferentiation and differentiation.

Differentiation: Overview

Below we have provided the overview of differentiation:

1. The cells derived from root apical meristem (RAM) and shoot apical meristem (SAM) and cambium differentiate, mature to perform specific functions.
2. This act leading to maturation is termed differentiation. They undergo a few or major structural changes both in their cell walls and protoplasm.
3. Differentiation is a permanent localised qualitative change in size, biochemistry, structure and function of cells, tissues or organs. E.g., Fibre, vessel, tracheid, sieve tube, mesophyll, leaf, etc.
4. Depending upon the location inside the plant and internal cellular mechanism, some genes are repressed (not allowed to express their effect) while others are allowed to show their effect. This causes the cells to behave in a particular fashion during growth and after maturation-
   i. Enlargement, lignocellulosic wall thickening and emptying in case of tracheids
   ii. Widening, some enlargement, wall thickening, emptying and loss of end wall in case of vessel elements.
   iii.  Loss of nucleus, vasuolisation and perforation of end wall in sieve-tube members.
   iv. Development of abundant chloroplasts in mesophyll cells
   v. Deposition of suberin in cell walls, tannins in protoplasts and then the death of cork cells
   vi. Deposition of silica in epidermal cells of grasses.
   vii. Differential wall thickening, small vacuoles, formation of a few chloroplasts and small size in guard cells.
   viii. nuclear division, a central canal and secretion of latex in laticifers.
   ix. Secretion of mucilage in the root cap.
   x. Elongation, thickening and emptying of sclerenchyma fibres.
   xi. Development of uneven pectocellulosic thickening in collenchyma.
   xii. Cutinisation of trichomes for preventing transpiration and formation of stationary air layer
   xiii. Development of schizogenous interspaces to form aerenchyma in aquatic plants.

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What is Dedifferentiation?

1. The cells derived from root apical and shoot-apical meristems and cambium differentiate and mature to perform specific functions, termed as differentiation.
2. During differentiation, cells undergo a few major structural changes and also develop very strong, elastic, lignocellulosic secondary cell walls, to carry water to long distances.
3. The living differentiated cells that have lost the capacity to divide can regain the capacity of division under certain conditions, termed as dedifferentiation.
4. Dedifferentiation is the regaining of the capacity to divide by differentiated cells in a particular part of the plant body. It allows a part of the plant to produce new cells.
5. Therefore, differentiated cells generally undergo dedifferentiation preliminary to major physiological or structural change.
6. During dedifferentiation, functional forms of the cells revert to their early developmental stages.
7. Hence, in plants, dedifferentiated cells serve as different forms of meristematic tissue including interfascicular vascular cambium, cork cambium, and wound meristem.
8. Furthermore, dedifferentiation often occurs in the lower life forms including amphibians and worms during their regeneration processes.

Fig: Regeneration in Hydra

What is Redifferentiation?

1. Redifferentiation is the loss of the regained capacity to divide by differentiated cells. It allows differentiated cells to serve as functionally-specialized cells in the plant body.
2. Generally, after preparing the plant body for physiological or structural change by dedifferentiation, the subjected differentiated cells revert to the redifferentiated form, performing a specific function.

Fig: Vascular Cambium, Secondary Xylem, and Secondary Phloem

3. For example, the dedifferentiated vascular cambium redifferentiates into the secondary xylem and phloem after undergoing cell division.
4. However, the cells in the secondary xylem and secondary phloem are incapable of further cell division and after maturation, these cells perform functions including conduction of food and water while providing structural integrity to the plant structure.

Difference Between Dedifferentiation and Redifferentiation

The difference between dedifferentiation and redifferentiation are as follows:

Criteria	Dedifferentiation	Redifferentiation
Definition	Dedifferentiation refers to the process by which structures or behaviours specialized for a specific function lose their specialization and become simplified or generalized	Redifferentiation refers to the process by which a group of once differentiated cells returns to their original specialized form.
Role	Dedifferentiated tissue acts as meristematic tissue including interfascicular vascular cambium, cork cambium, and wound meristem	Redifferentiated tissue serves as the functionally-specialized tissue. Hence, this is another difference between dedifferentiation and redifferentiation.
Importance	Dedifferentiation allows the plant body to produce new cells at a particular location	Redifferentiation is important to perform a function specific to a particular part of the plant.
Examples	The formation of the interfascicular cambium and cork cambium from fully differentiated parenchyma cells is an example of dedifferentiation.	The specialization of vascular cambium into secondary xylem and phloem is an example of redifferentiation.

Similarities Between Dedifferentiation and Redifferentiaiton

The similarities between dedifferentiation and redifferentiation are as follows:

1. Dedifferentiation and redifferentiation are two mechanisms in which cells alter their capacity to divide.
2. Differentiated cells undergo both processes.
3. Also, both mechanisms play a key role in the development and curing of injury.

Summary

The three phases of cellular growth are cell division, cell enlargement and cell differentiation, which bring maturity to the cells. Differentiation It is the permanent qualitative change in structure, chemistry and physiology of cell walls and protoplasm of cells, tissues and their organs. It is the result of the repression of genes, e.g., to form a tracheary element, the cells would lose their protoplasm. Dedifferentiation is the process of regaining the capacity to divide mitotically by differentiated cells.

Therefore, the dedifferentiated tissue serves as different meristematic tissue in the plant body. Thus, this process is important for the production of new cells at a particular location. In comparison, redifferentiation is the loosing of the regained capacity to divide by differentiated cells. It allows the functional specialization of these cells, giving them the ability to perform a unique function in the plant body. Therefore, the main difference between dedifferentiation and redifferentiation is the effect on the differentiated cells’ capacity to divide.

FAQs on Differentiation, Dedifferentiation and Redifferentiation

Q.1. What is dedifferentiation in plant cells?
Ans: Dedifferentiation is the reacquisition of pluripotency by transforming cells from a differentiated state to a less differentiated or stem cell-like state; dedifferentiation is a biological process connected with re-entry into the cell cycle, trans/redifferentiation, or even cell death.

Q.2. What is redifferentiation in plant tissue culture?
Ans: Redifferentiation also called budding in plant tissue culture, may begin any time after the first callus cell forms.

Q.3. What is the difference between dedifferentiation and redifferentiation?
Ans: In the dedifferentiation process, the cells that have lost the capability to divide regains their dividing property under certain conditions. On the other hand, the redifferentiation process is where the cells divide and produce cells that once again lose their dividing capacity but mature to perform specific functions.

Q.4. What is differentiation?
Ans: The process which leads to the maturation of cells is called differentiation. During differentiation, a few or major changes happen in the protoplasm and cell walls of the cells.

Q.5. Which one is the example of dedifferentiation?
Ans: The formation of meristems – cork cambium and interfascicular cambium from the fully differentiated parenchyma cells is an example.

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