Differentiation, Dedifferentiation and Redifferentiation

The cells derived from the root apical meristem, the shoot apical meristem and the cambium differentiate and mature to perform specific functions. This act, leading to maturation, is termed differentiation. During differentiation, cells undergo a few to many major structural changes in both their cell walls and their protoplasm.

• For example, to form a tracheary element, cells would lose their protoplasm and develop very strong, elastic, lignocellulosic secondary walls, so that they can carry water over long distances even under extreme tension.

Plants show another interesting phenomenon. Living differentiated cells that by now have lost the capacity to divide can, under certain conditions, regain the capacity to divide. This phenomenon is termed dedifferentiation.

• For example, the interfascicular cambium and the cork cambium are formed from fully differentiated parenchyma cells that have dedifferentiated.

While doing so, such meristems or tissues are able to divide and produce cells that once again lose the capacity to divide but mature to perform specific functions — that is, they get redifferentiated. Many of the tissues in a woody dicotyledonous plant are products of redifferentiation, and the same is true of the parenchyma cells of a callus that are made to divide under controlled laboratory conditions during plant tissue culture. …