Callus culture.

Put a piece of mature parenchyma on medium: with the right auxin and cytokinin it dedifferentiates into dividing callus, then redifferentiates into shoots or roots depending on the ratio.

Turn an explant into callus, then get shoots and not roots by changing only the ratio.

Dedifferentiated cells were never specialised; vascular cambium named as a dedifferentiation product.

• Cells produced by the root and shoot apical meristems and the cambium mature to perform specific functions. This maturation is differentiation, and during it cells undergo minor to major changes in their walls and protoplasm.
• Example: to become a tracheary element a cell loses its protoplasm and builds a strong, elastic, lignocellulosic secondary wall that can carry water over long distances even under extreme tension.
• Dedifferentiation: living differentiated cells that had lost the ability to divide regain it under certain conditions. Examples: interfascicular cambium and cork cambium formed from fully differentiated parenchyma cells.
• Redifferentiation: cells produced by such dedifferentiated tissue once again lose the ability to divide and mature to perform specific functions.
• Plant growth is open, and so is differentiation: cells from the same meristem can have different structures at maturity.
• Position helps decide the final form. A cell pushed out ahead of the root apical meristem becomes part of the root cap; a cell pushed sideways to the outer edge matures as epidermis.

Teaching this idea? Put the simulation on your own page or LMS with this code.