The beginning of the agronomic revolution, some 10,000 years ago, was characterized by the collection of seeds from important staple plants for use in the next season. But a crop such as maize, which involves the cross between two genetically dissimilar wild plants, could not have survived in the environment without the intervention of man. This is because it has no natural process for dispersing its closely bound seeds.
The developments in fermentation to provide more diverse foods with longer storage capacity and its use in bread making were applications of biotechnology. Thus, biotechnology was applied throughout history in the production of food without any real scientific understanding of what was occurring.
It was not until the end of the 19th century that the principles governing inheritance influenced the process of plant breeding as we know it today. However, it is really only from the 1960s onward that high-yielding varieties with agronomically beneficial traits and other quality characteristics have been developed and introduced into the market. This has resulted from applications of the technologies described in other chapters and forms the beginning of the biotechnological revolution. The effect of this revolution is most dramatically observed in the increase in yield of rice (Fig. 1) that occurred throughout Southeast Asia with a continued increase in yields from 1968 until 1983
However, despite the application of these technologies to plant breeding, and the outstanding success they have had, problems remain that are best solved through the application of genetic engineering or are tractable only using this approach. Only whole chromosomes can be introduced into plants by "conventional" means, and in doing so both "good" and "bad" traits can be transferred. The whole process of developing a new variety can take years with conventional approaches.
Conventional plant breeding simply cannot ensure that a staple crop contains a beneficial constituent, such as an essential nutrient, if the biosyn-thetic machinery for that consituent is not expressed. Conventional plant breeding does not readily provide the basis for determining the effect of specific genetic changes on quality because there is no control over the specific biosynthetic pathways that enable any relationship to be assessed. Indeed, the current critics of the use of biotechnology ignore the fact that many plant products on the market are derived from "wide crosses," hybridizations in which genes are moved from one species or genus to another to create a variety of a plant that does not, and could not, exist in nature.
Developments in genetic techniques have enabled molecular genetic approaches to replace gene identification by standard biochemical approaches. As an example, Arabidopsis mutants have been characterized with altered production of a number of nutrients and phytochemicals that are important determinants of plant quality including carotenoids (1), flavonoids (2), tocopherols (3), and ascorbic acid (4). Information about their biosynthesis and the function of specific genes in controlling these quality deter-
Increase in Rice Yields in Indonesia
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