Plant Growth and Development - Differentiation, dedifferentiation and redifferentiation
Review the key concepts, formulae, and examples before starting your quiz.
🔑Concepts
Differentiation: It is the process by which cells derived from root apical meristems, shoot apical meristems, and cambium mature to perform specific functions. During this, cells undergo structural changes in their cell walls and protoplasm (e.g., tracheary elements lose their protoplasm and develop strong, lignocellulosic secondary cell walls).
Dedifferentiation: This is the process where living differentiated cells, which have lost the capacity to divide, regain the power of division under certain conditions. Examples include the formation of interfascicular cambium and cork cambium from fully differentiated parenchyma cells.
Redifferentiation: The cells produced by dedifferentiated meristems (like interfascicular cambium or cork cambium) once again lose the capacity to divide and mature to perform specific functions. Examples include the formation of secondary xylem, secondary phloem, and phelloderm.
Open Differentiation: In plants, differentiation is open because cells arising from the same meristem can have different structures at maturity depending on their final location. For instance, cells positioned away from the root apical meristem differentiate as root-cap cells, while those pushed to the periphery mature as epidermis.
Development: It is the sum of growth and differentiation. It is represented as: .
📐Formulae
💡Examples
Problem 1:
During the formation of a tracheary element, a cell loses its protoplasm and develops a lignocellulosic cell wall. What biological process does this represent?
Solution:
Differentiation
Explanation:
Differentiation involves structural and functional specialization. The loss of protoplasm and the addition of lignin to the cell wall are specific structural changes that allow the cell to transport water efficiently under extreme tension, which is the definition of differentiation in plant cells.
Problem 2:
The formation of the interfascicular cambium from fully mature medullary ray cells is an example of which developmental process?
Solution:
Dedifferentiation
Explanation:
Medullary rays are made of mature parenchyma cells that have already differentiated. When they regain the ability to divide to form a part of the vascular cambium (interfascicular cambium), they are undergoing dedifferentiation.
Problem 3:
Identify the process when the cork cambium produces phelloderm (secondary cortex) and cork.
Solution:
Redifferentiation
Explanation:
The cork cambium itself is formed by dedifferentiation. When the cells produced by this 'dedifferentiated' cambium lose their ability to divide and mature into specialized tissues like cork or phelloderm, the process is called redifferentiation.