Plant biotechnology ushers in a new era for plant scientists working to maintain healthy plants, optimize crop yields, and minimize pesticide usage. One of the ultimate aims of agricultural biotechnology is to feed an expanding world population. A recent survey by The Economist shows that the world population has increased by 90% in the past 40 years while food production has increased by only 25% per head. With an additional 1.5 billion mouths to feed by 2020, farmers worldwide will have to produce 39% more grain (The Economist, March 25, 2000). These survey results aptly describe the food production challenges facing the global community of farmers and consumers in the new millennium and the dimension of the debate on the risks and benefits of developing genetically engineered crop plants to meet the increasing global food demand while preserving the environment.Genetic engineering has the potential to provide a cornucopia of beneficial plant traits, particularly an enhanced ability to withstand or resist attack by plant pathogens. New approaches to plant disease control are particularly important for pathogens that are difficult to control by existing methods. The percentage of crop losses caused by plant pathogens, insect pests, and weeds, has steadily increased to 42% worldwide, accounting for $500 billion dollars worth of damage (Oerke et al., 1994). In the United States alone, crop losses due to plant pathogens amount to $9.1 billion dollars, while worldwide, plant diseases reduce crop productivity by 12% (Food and Agriculture Organization, 1993). Worldwide, pesticide applications costing $26 billion dollars annually are applied to manage pest losses. Genetically engineered plants resistant to plant pathogens can prevent crop losses and reduce pesticide usage. This feature article provides a current perspective on four major areas of research and application of plant genetic engineering for resistance to plant pathogens.
Enhancing resistance with plant genes: Scientists from all over the world are investigating the biochemical nature of, and the signals involved in, a plant’s reactions to pathogen invasion and disease development. Plant resistance genes and the genes involved in resistance reactions are being identified and engineered into crop plants to protect them against plant diseases. This rapidly advancing field of investigation is described in this feature under Enhancing a plant’s resistance with genes from the plant kingdom.
Pathogen derived resistance: Plants can be protected from diseases with transgenes (genes that are engineered into plants) that are derived from the pathogens themselves, a concept referred to as pathogen-derived resistance. For example, plant viral transgenes can protect plants from infection by the virus from which the transgene was derived. Genetic engineering of plants for viral resistance is a thriving area of research and is described in this feature with special emphasis on research being done at Cornell University, Geneva, NY, under Genetic engineering: A novel and powerful tool to combat plant virus diseases.
Antimicrobial proteins: Another area of investigation involves peptides and proteins with antimicrobial properties that when produced by plants have the potential to strengthen plant resistance to fungal and bacterial plant pathogens. Fungi, insects, animals, and humans all contain genes encoding antimicrobial compounds. This use of antimicrobials to improve plant resistance to pathogens is described in this feature with special emphasis on research being done at Cornell University, Geneva, NY, under Using antimicrobial proteins to enhance plant resistance.
Plantibodies: Although plants have mechanisms to protect themselves against pathogen attack, in contrast to animals, there is no "immune system" per se in plants. With the advent of genetic engineering, plants can be engineered to express an antibody against a protein crucial for pathogenesis resulting in a level of immunity or resistance to the pathogen. This promising approach is described under Plantibodies: an animal strategy imported to the plant kingdom to fight back pathogens.Biotechnology is now a lightning rod for visceral debate, with opposing camps making strong claims of promise and peril. The debate involves not only scientific but also political, socio-economic, ethical, and philosophical issues (Wambugu 1999, Hails 2000, Ferber 1999, Trewavas 1999, Sagar et al. 2000).
This feature article provides a glimpse of the application of biotechnology to plant improvement. The dawn of a new era in plant pathology and plant protection is upon us. Biotechnology has rewritten the scope of scientific investigation, broadened the avenues to resistant plants, and challenged us to take safe and careful steps. Like any other new technology, much still needs to be done before the full potential of agricultural biotechnology is realized. As more and more plant biotechnology products become available, studies to evaluate the risks associated with biotechnology must be intensified. Findings from such studies must be easily accessible to the general public. The risks associated with this technology must be addressed and the benefits should be kept in mind. We are confronted with biotechnology’s vast perspective and this astounding view has expanded the very foundation of our understanding of life.
REFERENCES
Ferber, D. 1999. GM crops in the cross hairs. Science 286: 1662-1665.
Food and Agriculture Organization (FAO). 1993. "Production year book" FAO, Rome.
Hails, R. S. 2000. Genetically modified plants–the debate continues. Tree 15: 14-18.
Oerke, E. -C., Dehne, H. –W., Schonbeck, F., and Weber, A. 1994. "Crop production and crop protection: estimated losses in major food and cash crops." Elsevier, Amsterdam.
Sagar, A., Daemmrich, A., and Ashiya, M. 2000. The tragedy of the commoners: biotechnology and its publics. Nature Biotechnology 18: 2-5.
The Economist, March 25th, 2000 "Agriculture and Technology: Growing pains" pages 1-16 available at: (www.economist.com)
Trewavas A. 1999. Gene flow and GM questions. Trends in Plant Science, 4: 339.
Wambugu, F. 1999. Why Africa needs agricultural biotech. Nature 400: 15-16.
