Miracle or menace? : biotechnology and the third world / by Robert Walgate.

  • Walgate, Robert
Date:
[1990]
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Licence: Attribution-NonCommercial-NoDerivatives 4.0 International (CC BY-NC-ND 4.0)

Credit: Miracle or menace? : biotechnology and the third world / by Robert Walgate. Source: Wellcome Collection.

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    12 Miracle or menace? A FEW BASICS... tissue culture # As well as reproducing by seeds (so-called sexual reproduction), many plants can also reproduce themselves vegetatively. For example, a complete new plant can often be grown from a detached piece of root, shoot or leaf. In this case, the resulting new plants are genetically identical to their parent. # Plants (and all other organisms) grow by cell division. Cells grow to a certain size and then divide into two. When a cell divides, the genes it contains also duplicate themselves, so that an identical set is inherited by each new cell. # So all the cells arising from a single cell are genetically identical to it, and a plant that grows from a single cell or a small piece of cultured plant tissue is therefore genetically identical to the parent plant from which the tissue came. # This is the basis of plant cloning, or micro-propagation of plants in tissue culture. Tissue culture and genetic engineering As described in more detail in the next two chapters, biotechnology offers greater control and precision in determining which genes will be transferred, and also makes the task of transferring genes between different species much quicker and easier. Plant tissue culture (Chapter 3) and plant genetic engineering (Chapter 4), potentially offer breeders the chance to leap some of their hurdles. Tissue culture — growing small pieces of plant tissue or individual plant cells in culture, and propagating many new identical plants from them — is the real basis of plant biotechnology. It makes possible: • Large-scale, speedy propagation of elite varieties by making many clones, or identical copies, of a plant. This avoids the genetic variability that arises in crossbreeding. • Crosses between distantly related species, by fusing cells of the two species in tissue culture to produce a hybrid cell from which a new hybrid plant can be grown. • Easier international exchange of plant material, by providing disease-free material grown in tissue culture using parts of the plant that remain free of disease. • More ways of conserving and storing a wide variety of plant germplasm—the material such as seeds or tissue cultures from which new plants can be grown. Within any species of plant (or animal) there is considerable genetic variation from individual to individual. This reflects the fact that many genes exist in several different forms within the population as a whole. It is this variation that the plant breeder works with, and it must be conserved for the future. So much variation has
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