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Topic outline

 

  • Time: 10 hours
    Level: Intermediate

 
 

Introduction

  • Introduction Resource
  • In recent years, scientists have made huge gains in their understanding of how genes can be altered and transferred from one organism to another – but that knowledge has been acquired amidst controversy...
 

1 Genetic manipulation of plants and GM crops: an introduction

 

2 Genetic modification of plant cells

  • Preamble Resource
  • Your answers to Activity 1 will have revealed that the initial development of commercial GM crops has focused on the introduction of two traits: herbicide tolerance and insect resistance. However, many...
  • 2.1 Crown gall disease: genetic engineering in nature Resource
  • A. tumefaciens causes crown gall disease in a wide range of dicotyledonous plants. (Dicotyledonous plants, are also known as dicots, have broad leaves with branching veins. An example would be a broad...
  • 2.2 Using A. tumefaciens to genetically modify plant cells Resource
  • Genetic engineers have capitalised on the fact that part of the DNA from the Ti plasmid of A. tumefaciens is integrated into the plant genome during the infection process. Ti plasmids can be isolated and...
  • 2.3 From infected cells to transgenic plants Resource
  • Unlike the ‘natural’ infection process, where only the cells at the site of the crown gall are affected by the inserted T-DNA, scientists wanted to introduce new genes into all the cells of the plant....
 

3 Common traits introduced by GM

  • 3.1 Insect resistance Resource
  • We will now look briefly at the science underlying the traits introduced into commercial crops, which you explored in Activity 1; a useful place to start is by considering how the property of resistance...
  • 3.2 Herbicide tolerance Resource
  • As you discovered from Activity 1, herbicide tolerance is the trait most commonly incorporated into commercial GM plants. A crop can be made tolerant to herbicide by inserting a gene that causes plants...
 

4 Golden Rice: a case study

  • Introduction Resource
  • In the previous section, you explored the science related to the development of the two traits found in the early commercial GM crops. Their production has been driven by commercial imperatives, and some...
  • 4.1 Vitamin A deficiency Resource
  • Vitamin A, more properly known as retinol, is an important chemical intermediate in a number of biochemical processes in mammals. It is involved in vision, and is found in the rod cells of the retina of...
  • 4.2 The science behind Golden Rice Resource
  • Modifying crops to produce the Bt toxin (Section 3.1) was, in some ways, relatively simple. The toxin is a single protein and can therefore be produced as a result of the insertion of a single gene into...
  • 4.3 Golden Rice in the public domain Resource
  • In January 2000, the successful experiments were announced in a paper published in the American journal Science. This, in itself, is significant. Generally, work on genetic manipulation would be published...
  • 4.4 The ongoing story Resource
  • At the time of writing (2006), the Golden Rice tale is an unfinished story. Some of the developments of the last five years are summarised here.
 

5 Summary

  • 5 Summary Resource
  • At the time of writing (2006) a relatively small number of types of GM crop have been grown globally, in a limited number of countries. The take-up of these crops has been relatively high in countries...
 

References and Acknowledgements

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