Q.53 The plant cells are considered totipotent. The phenomenon of a mature cell reverting to the
meristematic state and forming undifferentiated callus tissue is called
(A) redifferentiation (B) dedifferentiation
(C) organogenesis (D) recalcitrancy
The correct answer is (B) dedifferentiation. Plant cells exhibit totipotency, allowing mature, differentiated cells to revert to a meristematic state and form undifferentiated callus tissue through dedifferentiation.
Option Explanations
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(A) Redifferentiation: This is the process where dedifferentiated cells (like callus) lose their division capacity and mature into specialized tissues or organs, such as shoots or roots.
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(B) Dedifferentiation: Mature differentiated cells regain meristematic properties, divide rapidly, and form undifferentiated callus; this matches the question exactly.
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(C) Organogenesis: Formation of organs (shoots/roots) from callus or explants via redifferentiation, not the initial callus formation.
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(D) Recalcitrancy: Refers to the inability of certain plant tissues to respond to in vitro culture or regenerate, opposite of totipotency.
Plant cells totipotent nature allows dedifferentiation, where mature cells revert to meristematic state and form undifferentiated callus tissue, key for tissue culture.
Dedifferentiation Process
Dedifferentiation occurs when differentiated plant cells regain division ability under hormones like auxins, producing callus—a mass of undifferentiated, meristematic cells. This demonstrates totipotency, as seen in explants for regeneration.
Comparing Key Terms
| Term | Description | Role in Tissue Culture |
|---|---|---|
| Dedifferentiation | Mature cells → meristematic, form callus | Initial step for totipotency activation |
| Redifferentiation | Callus cells → specialized organs | Organ formation from callus |
| Organogenesis | Shoot/root development from callus | Plantlet regeneration |
| Recalcitrancy | Failure to regenerate in culture | Barrier in non-responsive species |
Applications in Biotechnology
These processes enable mass propagation, genetic engineering, and CSIR NET topics like cellular totipotency. Callus from dedifferentiation supports indirect organogenesis.
