Pasture & Range: September 2003 Other Pasture & Range Articles

Plant biotechnology is a process in which genetic information and techniques are used to develop useful and beneficial plants. Humankind has been genetically modifying the food supply for centuries by traditional selection and breeding. Plant biotechnology is an extension of this traditional plant breeding with one very important difference — modern plant biotechnology allows for the transfer of a greater variety of genetic information in a more precise, controlled manner. Unlike traditional plant breeding, which involves the crossing of hundreds or thousands of genes, plant biotechnology allows for the transfer of only one or a few desirable genes. This more precise science allows plant breeders to develop crops with specific beneficial traits and without undesirable traits.

Plant biotechnology has become a powerful agricultural technology that is beginning to increase productivity by reducing or eliminating losses caused by weeds, pests and pathogens. It is also having a positive impact on human health and the environment by reducing the use of agro-chemicals. The science of plant biotechnology came of age with the first-ever large scale commercial planting of transgenic crops in 1996. This milestone was achieved after years of intensive work devoted to the development of reliable systems for plant regeneration from cultured cells and of methods for the introduction and stable integration of foreign genes into cultured plant cells. The first generation of transgenic crops now being grown has been engineered for resistance to herbicides (soybeans, canola), insects (cotton, maize) and viruses (papaya and squash).

The science behind transgenic plants is sound, precise and predictable. Once a gene of interest has been identified, it is isolated and sequenced. Its function and the protein coded by it are determined. It is then introduced into a crop variety that has been found to be suitable for genetic transformation and regeneration. Performance of independently transformed lines are rigorously tested and evaluated in the laboratory, greenhouse and in the field for several generations. Further exhaustive testing for yield and overall performance, environmental/ecological effects, nutritional value, allergenicity and other qualities is needed before the release of a transgenic cultivar.

Biotechnology continues to be the most rapidly adopted technology in agricultural history due to its social and economic benefits. The estimated global area of transgenic crops for 2002 is 145 million acres. A sustained rate of annual growth of more than 10 percent per year has been achieved since their introduction in 1996. During the seven-year period of 1996 to 2002, the global area of transgenic crops increased 35-fold, from 4.2 million acres in 1996 to 144.4 million acres in 2002. On a worldwide basis, the principal biotech crops were transgenic soybean occupying 89.8 million acres in 2001 (62 percent of global area), followed by transgenic corn at 30.5 million acres (21 percent), transgenic cotton at 16.7 million acres (12 percent), and transgenic canola at 7.4 million acres (5 percent). The United States has been the driving force in development and adoption of the technology. The United States grew 95.9 million acres (66 percent of the global total) of transgenic crops in 2002.

Biotech research in forages has been lagging behind that of major cash crops. Forages are the most widely grown, but probably least appreciated, commodity. When consideration is given to their direct and indirect benefits, it is obvious that research and development in this agricultural sector have been neglected to a large extent. This may reflect that, in contrast to cash crops, the cash value of forages is realized through animals. Thus, the public may not realize the direct connection between forage production and the great diversity of forage-based commodities (e.g., meat, milk, wool). Since livestock productivity depends largely on their forage utilization, the value of forages may be estimated using feed cost associated with livestock production. Based on this model, the calculated value of forages far exceeds the cash value of any other crop in the United States. Due to the great complexity of forage species and the associated difficulties encountered by traditional breeding methods, the potential of biotechnology for the development of improved forage cultivars has been recognized.

The Noble Foundation has taken an integrated approach to improve forages by establishing the Forage Biotechnology Divison in 1997. One of the Forage Biotechnology programs, tissue culture and genetic transformation, is aimed at producing transgenic forages to complement or accelerate the breeding program. The development process in this program generally involves establishment of efficient plant regeneration and genetic transformation systems for different forage species; cloning of potentially useful agronomical genes and promoters; and generation of transgenic forage plants with improved agronomic traits. Once useful transgenic material is identified, such material is incorporated into the traditional breeding programs of Forage Biotechnology.

Our research focuses on forages capable of prospering in the southern Great Plains and the surrounding regions. Forages having such potential include grasses such as tall fescue and bermudagrass and forage legumes such as alfalfa and white clover. We have established reliable plant regeneration and genetic transformation systems for several different forage species.

Depending on importance and feasibility, the agronomic traits initially sought to be a part of this forage improvement program include forage digestibility, drought tolerance, and phosphate uptake. We have made progress in each of the projects.

1. Forage quality, especially when plants mature, is a limiting factor for animal production. It is known that lignification of plant cell walls is largely responsible for lowering digestibility of forage tissues. By down-regulating a major lignin gene, we have been able to increase forage digestibility in tall fescue.
    
   
2. Drought stress on perennial forages is a regular feature in the southern Great Plains. Genes involved in drought response have been isolated and transgenic plants are being generated and characterized.
    
   
3. Improving plant phosphate uptake may have an impact on forage production, since phosphate is immobile in soil and very often deficient. A root-specific promoter has been cloned, which is capable of directing gene expression in root tissues only. The project is aimed at providing forage plants the capacity to take up more phosphate from the soil.

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