TABLE OF CONTENTS The most widespread use of agbiotech methods is in support of conventional breeding programmes, where new molecular markers and tissue culture techniques are having a considerable impact. The present commercial use of transgenic crops is almost entirely limited to the manipulation of a few input traits in a very small number of major commodity crops. There are many other examples of potential transgenic crops being developed with modified output traits, but the widespread commercial cultivation of such crops probably lies some years ahead. The Biotechnology Industry Organisation in the USA provides a list of transgenic and non-transgenic agbiotech products that are either already on the market or under development for release in the next six years (http://www.bio.org/er/agri-products.asp).
Classical plant breeding relied on the selection of favourable characters from the diverse gene pool that is present in any biological species. Often these characters were visible and easily identified, e.g. height or flower colour or resistance to fungal attack. In other cases, the characters were much more subtle and sometimes could only be measured by sophisticated analytical techniques, e.g. the amounts of certain secondary products or the fatty acid composition of the seed oil. In all of these cases, it was necessary for the breeder to grow up and analyse each new generation before it was possible to measure the character, or phenotype, and select the appropriate plants. The advent of marker-assisted selection has changed this as breeders can now select a few...
