Animal and Plant Genomic Research
Lawrence B. Schook and A. Lane Rayburne
The current emphasis of biotechnology in animal and plant agriculture is the need to identify and manipulate genes affecting disease resistance, growth, and other economically important traits (for example, seed-oil content or fat content of meat or milk). By constructing "genetic road maps" for major livestock and food crops, researchers can assist producers in providing improved and safer food for world markets. Genomic research also provides tools for applying this information through improved breeding programs, direct manipulation of genes through growth promotants, and - through genetic transformation - the ability to create unique new animals and plants resistant to diseases and adaptable to variable climate conditions.
Approaches and Tools
Research initiatives in both animal and plant genomic research have provided new methods and tools for using standard principles of breeding and selection. Domestication of animals and the development of hybrid crops have served us well. Our understanding of the organization of animal and plant genomes (genetic composition) has increased greatly in recent years. Our interest in learning about the human genome has provided a strong scientific base for agricultural efforts.
Several approaches are used to map, identify, and characterize genes. Linkage mapping uses crosses to locate genes relative to others in progeny. Restriction fragment length polymorphisms (RFLPs) play an integral role in creating genetic linkage maps (see related sidebars by Dudley and Rocheford). In RFLP maps, special enzymes are used to cut the deoxyribonucleic acid (DNA) of an organism into smaller pieces. The patterns revealed by probing the cut DNA provide information that can be used to determine linkage of traits to specific RFLP patterns. Establishing such linkages allows both animal and plant researchers to more efficiently develop organisms of increased agricultural performance.
Another method to identify and characterize genes is to physically identify their location on chromosomes and to clone genes using recombinant DNA technologies. The use of recombinant DNA techniques is extremely important in constructing novel genes to enhance and control the proteins encoded by them, which affect production traits.
Graduate student Suzanne Boussard prepares a DNA sample for electrophoresis. Electrophoresis is the movement of molecules through a fluid or gel under the action of an electric current.
Benefits to Producers and Consumers
Lawrence Schook and Harris Lewin, Department of Animal Sciences, organized a USDA-supported international conference, "Mapping Domestic Animal Genomes: Needs and Opportunities," during April 1990. Participants represented international industry, governments, universities, and research institutions. A major recommendation was to develop genetic linkage maps for the agriculturally important animal species, maps to explore and use the genes for disease resistance, reproduction, and growth traits.
Currently, the Department of Animal Sciences has several research projects funded by the USDA, the National Pork Producers Council, and various international agencies. Lewin is developing strategies and techniques (RFLPs of individual sperm) to detect major genes affecting growth, lactation, and development in cattle. His group is one of the first to demonstrate how genomic markers can be used to select animals for faster growth and meat properties.
James Robinson and Roger Shanks are using new molecular approaches to identify dairy cattle that carry a recessive gene responsible for embryonic death. Scientists collaborating in the colleges of Agriculture and Veterinary Medicine focus on providing safer food by understanding the genetic basis of salmonella food poisoning and how the bovine leukemia virus affects milk production.
The recently imported Chinese pigs have stimulated new research activities. For example, a multidisciplinary team (Schook, Lewin, David McLaren, and Matthew Wheeler) has initiated a long-term program to determine the genetic basis for carcass composition and reproductive prolificacy in swine.
An international program headed by David Thomas is using genomic research methodologies aimed at improving the prolificacy of sheep.
University of Illinois researchers are also providing leadership in developing new techniques that unravel the mysteries of inheritance. Rohan Fernando has developed statistical models for using genetic markers to assist in animal selection to increase rates of genetic improvement. Lewin, Wheeler, Carol Whetstone, Marite Ivanova, and Schook are developing strategies to manipulate genetically and select embryos that will result in cattle and pigs with enhanced growth, meat quality, and disease resistance.
In the last decade, major advances in molecular biology have permitted the incorporation of novel genetic material into plant species. Cultivated plant species will realize the promise of this technology through the addition of genes that will result in the decreased use of pesticides, increased pest resistance and nutritional value, enhanced adaptation to environmental stress, and alternative uses for the plants.
Dudley and Rocheford have used genetic road maps to identify genes controlling quantitative traits of economic importance in corn. In crops such as soybeans where molecular maps are not yet fully developed, Ted Hymowitz and Lila Vodkin are providing valuable information for developing these maps.
Genome mapping studies, while important to genetic manipulation, are not the only ongoing genomic research at the University of Illinois. Researchers are working to improve transformation and regeneration of specific crop species (Jack Widholm), to identify and manipulate genes to target for transformation (Alan Kriz), and to optimize the expression of genes introduced into plant species in both the amount of product and which tissues are producing the product during plant development (Steven Farrand and Angus Hepburn).
Critical to the manipulation of crop plants is increased understanding of the plant genome. Aided by the facilities of the Cell Sciences Laboratory of the Biotechnology Center, A. Lane Rayburn is investigating the organization of genetic material in plant chromosomes and nuclei.
Future Perspectives
The continued development of scientific tools used in genomic research will help the U.S. agricultural community remain competitive in world markets and in position to enter new and specialized domestic and foreign markets. Researchers at the University of Illinois are at the forefront of genomic research, and the new Plant and Animal Biotechnology Laboratory will provide state-of-the-art facilities to maintain this leadership role.
Lawrence B. Schook, professor of molecular immunology, Department of Animal Sciences, and A. Lane Rayburn, assistant professor of cytogenetics, Department of Agronomy
