Course: SAT 170 Introductory Biotechnology

Unit 8 Reading and Multimedia Assignment

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“Whole plant cloning," by Boundless, CC BY SA 3.0

https://www.boundless.com/biology/biotechnology/stem-cells-and-cloning/whole-plant-cloning/
Reading Assignment: Whole plant cloning
With plants, a fully differentiated cell can undergo de-differentiation to produce all the cell types needed in an adult plant.

Frederick "Camp" Campion Steward (1904-1993) was a British botanist and plant physiologist who established that plants could be totally regenerated from one cell, while he was working at Cornell University. The finding revolutionized the world of plant cell biology, establishing for the first time that plant cuttings and shoots were no longer required to propagate hybrids and create mutations, but that individual plant cells contained all the necessary information to regulate the entire plant organism (see above figure). His discovery of the means to obtain such regeneration has formed the basis of the entire field of plant molecular biology, meaning that clones, hybrids, and mutations of plants can be accomplished in the laboratory rather than having to resort to the far longer and cumbersome process of taking and then cultivating cuttings.

Dedifferentiation is a cellular process often seen in more basal life forms such as worms and amphibians in which a partially or terminally differentiated cell reverts to an earlier developmental stage, usually as part of a regenerative process. Dedifferentiation also occurs in plants. Cells in cell culture can lose properties they originally had, such as protein expression, or change shape. This process is also termed dedifferentiation.

It is a very common practice to vegetatively propagate cultivars that have desirable characteristics. Man-made methods of vegetative reproduction are usually enhancements of natural processes, but range from rooting cuttings to grafting and artificial propagation by laboratory tissue culture. In horticulture, a "cutting" is a piece that has been cut off from a mother plant and then caused to grow into a whole plant. Often this involves a piece of stem that is treated with rooting liquid or powder containing hormones. In some species root cuttings can produce shoot growth. When the cutting has become a self-sufficient plant, it is genetically identical to the mother plant.

A related form of regeneration is that of grafting. A stem piece or a single bud (the scion) is joined onto the stem of a plant that has roots (the rootstock), or a stem piece can be joined to a root piece. A popular use of grafting is to produce fruit trees, sometimes with more than one variety of the same fruit species growing from the same stem. Rootstocks for fruit trees are either seedlings or propagated by layering.

Plant tissue culture relies on the fact that many plant cells have the ability to regenerate a whole plant, a quality known as totipotency. Single cells, plant cells without cell walls, pieces of leaves, or (less commonly) roots can often be used to generate a new plant on culture media given the required nutrients and plant hormones.