Plants are vital to our existence. They provide the oxygen we breathe, the food we eat, the fibers for our clothes, the materials to build our homes, and the raw goods for our industries. A quarter of our medicinal drugs comes from plant species. The paper on which this report is printed is a plant product.
Yet, despite the important contributions of plants to our standard of living, far less is known about them than about mice, flies, or the bacteria that inhabit our intestines. We need to learn more about how plants grow and develop; how they produce useful chemicals; how they protect themselves from pests; and how they sense, respond to, and even alter our environments. One way to learn these things is through study of a plant's genes. The information that plants use to grow and develop, and to interact with their environment, is coded in their genomes. To fully understand plants, we need to read and interpret their genomic information.
In the 1980s, there was a growing awareness that significant investments in studies of many different plants, such as corn, oilseed rape, and soybean, were diluting efforts to fully understand the basic properties of all plants. Scientists began to realize that the goal of completely understanding plant physiology and development is so ambitious that it can best be accomplished by turning to a model plant species that many scientists then study. Fortunately, because all flowering plants are closely related, the complete sequencing of all the genes of a single, representative, plant species will yield much knowledge about all higher plants. Similarly, discovery of the functions of the proteins produced by a model species will offer much information about the roles of proteins in all higher plants.
During the last 8 to 10 years, Arabidopsis thaliana has become universally recognized as a model plant for such studies. Although it is a non-commercial member of the mustard family, it is favored among basic scientists because it develops, reproduces, and responds to stress and disease in much the same way as many crop plants. What's more, Arabidopsis is easy and inexpensive to grow, and produces many seeds; this allows extensive genetic experiments, often involving tens of thousands of plants. Also, Arabidopsis has a comparatively small genome, thereby simplifying and facilitating genetic analysis. Compared to other plants, it lacks the repeated, less-informative DNA sequences that complicate genome analysis.
Initially, there was much debate about whether an improved understanding of Arabidopsis would help in the breeding of commercial crops, and much controversy over decisions to devote limited resources to this non-commercial species. However, the many advances reported over the past few years offer clear evidence that this plant is not only a very important model species for basic research, but also extremely valuable for applied plant scientists and plant breeders. Publications on Arabidopsis in top-quality journals are increasing exponentially, following substantial increases in investment by many governments. In the United States, for example, the U.S. Department of Agriculture, the Department of Energy, the National Institutes of Health, and the National Science Foundation collectively supplied US$7.5 million in 1990 for Arabidopsis research and US$22 million in 1993. And the European Community has invested a significant portion of its biotechnology research resources to Arabidopsis genome research over the last 5 years. In fact, many of the world's leading laboratories in plant science have initiated programs using Arabidopsis, and many young plant scientists have chosen to start their careers using this species.
But how can discoveries with Arabidopsis contribute to the development of improved crops? Simply put, once a gene has been discovered in Arabidopsis, the equivalent gene may be found more easily in other plants. Thus, the function of many genes isolated from crop plants can be better understood via study of their Arabidopsis homologues. So knowledge gained from Arabidopsis on the defense mechanisms against pathogens, for example, can be used directly to develop disease-resistant plants in other species.
Genetic comparisons between Arabidopsis and crop species are increasing, as shown by the large number of Arabidopsis publications cited for 1993 that also involved studies of crop plants such as soybean, rice, maize, wheat, barley, rye, pepper, tomato, potato, cotton, or sorghum. There is ample reason to believe that, in the coming years, Arabidopsis will serve more and more as a resource base for breeders of crop plants and as a model plant species that furthers the knowledge of plant scientists worldwide.