Differentiation, Dedifferentiation, and Redifferentiation
- Differentiation is the process in which cells in meristems (root apical and shoot-apical) and cambium differentiate and mature to perform specific functions.
- Cell walls and protoplasm undergo major structural changes, and the capacity for cell division is lost.
- Under certain conditions, living differentiated cells regain the capacity to divide. This is called dedifferentiation.
- Dedifferentiated cells divide and produce cells that lose the capacity to divide but mature to perform specific functions. This is called redifferentiation.
- Plant growth is open, meaning it can be indeterminate or determinate. Differentiation in plants is also open, as cells/tissues from the same meristem have different structures at maturity.
- Final structure at maturity of cell/tissue is also determined by the location of the cell.
E.g., Loss of protoplasm to form a tracheary element. These develop strong, elastic, lignocellulosic secondary cell walls to transport water over long distances under extreme tension.
E.g., Formation of meristems (interfascicular cambium and cork cambium) from differentiated parenchyma cells.
E.g., Cells positioned away from root apical meristems differentiate as root-cap cells, while those pushed to the periphery mature as epidermis.
Development
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Development is the process encompassing all changes in an organism’s life cycle, from seed germination to senescence. It is the sum of growth and differentiation.
- Plants follow different pathways in response to the environment or phases of life, forming varied structures. This ability is called plasticity. E.g. Heterophylly (presence of different types of leaves at different phases of life or due to different environments).
- Heterophylly due to phases of life: In cotton, coriander, and larkspur, leaves of juvenile and mature plants differ in shape.
- Heterophylly due to environment: Differences in leaf shapes produced in air versus water (e.g., buttercup).
Factors controlling development:
- Intrinsic factors: Include intracellular (genetic) or intercellular factors (e.g., plant growth regulators).
- Extrinsic factors: Include light, temperature, water, oxygen, nutrition, etc.