The genetic manipulation of plants

1 Genetic manipulation of plants and GM crops: an introduction

In this unit we will consider the genetic manipulation of plants, and the production of GM crops. A great deal has been written about the science of GM crops and the controversial issues surrounding their introduction around the world. In the study time available, we will focus on a small number of selected issues.

In this unit you'll have the opportunity to learn more about the science that has been used to engineer a range of GM crops, and examine both the science and social concerns relating to the development of a nutritionally enhanced rice, known as ‘Golden Rice’.

Unit S250_2 Social issues and GM crops will explore in greater detail some of the social issues surrounding the development of GM crops. These issues have been selected for their intrinsic interest and for the light they throw on all four of the course themes. You will explore some of the underlying ethical issues, some of the problems that occur when GM issues are communicated within and outside the scientific community, and how the supposed risks attached to GM foods might be evaluated. You will consider how public concerns about GM crops might be sampled as a prelude to decision making, attempting to balance the different interests of experts, industry and the consumer.

You are likely to have your own feelings and opinions about the development of GM crops and food. We would like you to explore these feelings before you embark on the study of this unit, by taking five minutes to consider questions that were developed to assess the views of participants in a UK-based public debate called GM Nation? We will explore this public debate in some detail in unit S250_2 Social issues and GM crops. You may find it interesting to see if your opinions change as a result of studying the scientific and social issues.

Your own experience of the GM controversy is likely to have been shaped by events in the country where you live. However, GM technology in plants raises issues of global importance, approached and resolved in very different ways, that often mix local, national and global perspectives. In India for example, attitudes to GM have been shaped in part by concerns about the influence of foreign multinationals, as opposed to home-grown technologies. India's Government supports local research into high-protein potatoes, high-yield mustard and drought- and salt-tolerant rice. But it has banned the import of maize or soya flour from US aid agencies, after several Indian environmental organisations protested against the GM content of such products. In the US, there is a generally high level of acceptance and utilisation of GM foods and there is no requirement to label products derived from transgenic crops. Clearly, many factors outside science influence decision making, and these may well differ between countries. We will explore some of these issues, but initially, it is useful to have an overview of the position of GM crops globally.

Activity 1

You should allow 0 hour(s), 30 minute(s).

Click on the 'View document' link below to open and print out a copy of the survey that accompanied the GM Nation? debate. Do not spend a great deal of time considering the answers – the idea is to get a quick snapshot the debate.

View document

Part (b) – 30 minutes

The idea of this part of the activity is to gain an overview of what types of GM crops are being grown around the world. GM crops were first grown commercially in 1995 and the data here are for the year 2004. Begin by examining Figure 1, and Table 1.

Figure 1: World map showing the countries growing GM crops commercially in 2004. The map includes, for each country, the area sown with GM crops and the major crops grown.

Table 1:The take-up of GM crops in 2004.

Crop Herbicide tolerance Insect resistance Herbicide tolerance and insect resistance combined Total
soybean 48.4 48.4
maize 4.3 11.2 3.8 19.3
cotton 1.5 4.5 3.0 9.0
canola (oilseed rape) 4.3 4.3
total 58.5 15.7 6.8 81.0

Note: this table gives the area (in millions of hectares) given over to the cultivation of each type of GM crop: herbicide-tolerant, insect-resistant, and with both attributes combined. No other GM crops were grown on a significant scale.

Using the data in Figure 1 and Table 1, try to get an overview of which GM crops are grown and where:

(i) Which countries form the top five in terms of total area of GM crops, and what percentage of the area sown with GM crops is grown in these countries?

(ii) Given that a reasonable estimate of total area of cultivated land in 2004 would be approximately 1400 million hectares, what percentage of the world's cultivated land is used to grow GM crops?

(iii) In 2003 it was estimated that 47.3 million hectares were sown with GM crops in developed countries, with 20.4 million hectares in the developing countries. Find the areas sown in 2004 and calculate the percentage increase in each case. Comment on any differences you observe.

(iv) Use your answers to (i)–(iii) to write a few sentences (no more than 100 words) summarising the position of GM crops in global agriculture in the year 2004. It is important that you write down your thoughts at this stage, because you will be asked to look back at your ideas when you tackle later activities.


Seventeen countries grew GM crops, and four types of crops were grown. Were you surprised to learn that in 2004, after nine years of commercial cultivation, there were only four types of GM crop grown globally in significant amounts? These crops were modified to show either herbicide tolerance, insect resistance, or both these traits. (We will examine in Sections 2 and 3 how the traits are introduced and how they work.)

(i) The top five GM crop-growing countries are, in order, the USA, Argentina, Canada, Brazil and China. It is significant that three of these five are in the developing world. These countries had a total area of 77.9 million hectares of GM crops, forming 96% of the 81.0 million hectares sown globally.

(ii) These 81.0 million hectares used to grow GM crops covered just under 6% of the world's cultivated land. Nevertheless, this is a very large area, over three times the land area of the UK.

(iii) In 2004, 53.4 million hectares in developed countries were used to grow GM crops, compared to 27.6 million hectares in developing countries. Significantly, these represent annual increases of 13% and 35% respectively. It appears that GM crops are being taken up in developing countries far more quickly than in developed ones. (This is explored further in Section 3.)

(iv) I would summarise the global position of GM crops in 2004 as follows:

The area of land sown with GM crops has grown extremely quickly in the nine years since they were first grown commercially, in 2004 forming 6% of the global area of cultivated land. However, take-up has been limited to 17 countries, and five of these cultivate over 96% of the area sown. The types of GM crops grown were also limited; in 2004 only four different GM crops were grown, modified to show herbicide tolerance or insect resistance or both traits.