Craig W. Edminster1
Abstract
Traditional plant breeding has had an enormous impact on the worldwide turfgrass seed industry over the past 40 years. Genetic selection and recombination has resulted in the introduction of new and improved cultivars among species of warm and cool-season turfgrass. In concert with traditional breeding a new tool is available that may revolutionize not only the turfgrass breeding, production and marketing industry but how we manage turfgrass on the golf course greens, home lawns or sports ovals. Genetic engineering refers to manipulating the DNA, or genes, of an organism. Plant transformation refers to the process of introducing a gene from some other organism into a plant species. These genetically modified grasses or "GMG's" may provide improved herbicide resistance, insect resistance, salt tolerance and disease resistance that would be impossible using traditional breeding methods alone. This new science is stimulating a need for more defined collaborative effort between public universities, biological institutes and private seed companies. A comprehensive review of the integration of classical and genetic engineering to develop improved turfgrass cultivars will be reviewed.
INTRODUCTION
The turf and forage seed market in the USA is the second largest seed market second only to hybrid corn with annual sales of US$580 million. There are over 14,000 golf courses, 30,000 athletic facilities and over 40 million lawns and parks in the U.S.A. The maintenance of these turf areas ranges from intensive maintenance on golf course greens, tees and fairway to low maintenance conditions on many home lawns, parks and commercial sites. Intensively managed turf generally requires pesticide (herbicides and fungicides) treatments to prevent disease and remove unwanted weeds. The turfgrass industry much like corporate agriculture has been accused of improper utilization of pesticides by the sustainable environmental movement for years. It is estimated that 350 thousand tons of pesticide are used annually by the agricultural and horticultural sector of the U.S.A. Production of turfgrasses that can use significantly less pesticide would be beneficial to the turfgrass industry.
CLASSICAL PLANT BREEDING
Genetic engineering is nothing new. Even before Mendel published his garden pea inheritance studies in 1866, man has selected the best plants and animals for continued propagation. American Indians bred maize plants. The Assyrians and Babylonians artificially pollinated date palms in 700 B.C. Modern plant breeders developed dwarf wheat cultivars. These new "green revolution" cultivars set new records for production and yield. Development of cultivars is a long, tedious process. Thousands of potential cultivars are tested to determine their production value. Genetic variation and the ability to recognize these differences in a testing program are the key aspects to any successful cultivar breeding program. Plant breeders us many methods to develop new cultivars including natural selection, phenotypic selection, genotypic selection, chromosome crossover, naturally and chemically introduced mutations, variation in chromosome number and others. There are many limits to classical plant breeding progress. They include but are not limited to outcrossing, self-incompatibility, polyploidy, polygenic traits, and physical and biochemical barriers to cross compatibility among and between plant species. In essence useful genes from one species are simply impossible to introduce into another species in many classical breeding program. Hence, classical breeding whether additive or epistatic have limits in their complete effectiveness in overcoming pest, disease and other abiotic and biotic stress. One must remember that the first transformation in crop plants was made 12 years ago (Kanomycin resistance in Tobacco) and initial work on herbicide and insect resistance in species such as corn, cotton and soybeans is no more than 10 years old. Commercial lives of these GMO products are less than 5 years old! What are these transformations and why are they so popular?
PLANT BIOTECHNOLOGY
The advent of recombinant DNA technology allows a significant step, as gene sequences previously moored in different organisms could be recombined. Biotechnology comprises four main areas including gene transfer, molecular diagnostics, cell biology and informatics. Turfgrass, like other major crop species such as maize, wheat, rice and barley, is difficult to manipulate in vitro. The development of embryogenic tissue cultures provides a major resource for the genetic transformation of many crops including turfgrass. A review of the present status of turfgrass biotechnology will be reviewed in detail in the "Gene Technology for Greens Workshop" scheduled for the 8th of June and includes:
- identification of the gene for resistance - isolation and cloning of the gene - species to be transformed - plant regeneration - transformation methods - studies of function and regulation - transfer of the gene and other expressive factors - field tests - prospects for commercialization
GENETICALLY MODIFIED TURFGRASS
Currently there are no genetically modified turfgrasses commercially available. There are three major reasons turfgrasses are being considered for enhancement or genetic transformation. 1). Turfgrass has been singled out with production agriculture as an abuser and large user of pesticides, therefore there are environmental concerns related to the current utilization, management and maintenance of turfgrass. 2). There is currently increased economic incentive to develop environmentally friendly turfgrasses. Those first to the market will reap benefits of this emerging market. 3). The technology is now available to successfully to transform turfgrasses.
A review of these reasons concludes that it is now possible to protect the environment by substituting a safer pesticide, Roundup (glyphosate) or the Baccillus thuringiensis (Bt) for other less safe pesticides like 2,4-D, while earning a return on investment in an over one-billon-dollar turfgrass seed and sod market. Although RoundUp resistance is mentioned as an initial introduction of an important characteristic, there are other characteristics that are being considered for commercial research and transformation including, glufosinate (Finale) resistance insect, fungi, virus and insect; tolerance to stresses such as drought, cold, salt and aluminum and reduced vegetative growth. However, the characteristic most easily understood, selected for and with the most agronomic stability, is RoundUp resistance. Therefore, this will be the first characteristic that appears in a turfgrass. The turfgrass species initially targeted for transformation include Kentucky bluegrass, creeping bentgrass and buffalograss, because their adaptation covers a significant portion of the United States. Surveys of lawn enthusiast have shown that significant numbers would be interested in using a RoundUp resistant product.
ECOLOGICAL EFFECTS OF PEST RESISTANCE GENES IN MANAGED ECOSYSTEMS
The use of biotechnology in agricultural and horticultural production also bring with it questions regarding the potential of genetically modified organisms (GMOs) to cause unacceptable impacts on the environment. Paramount among the ecological issues associated with transgenic crops is the possibility that some newly introduced traits, such as pest or pathogen resistance, could confer added fitness to the crop. As a result, the crop may gain weedy characteristics if its ability to survive and spread outside of cultivation is enhanced. A second issue arises if such crops are grown in the vicinity of compatible cultivated (commercial seed production) wild or weedy related species; transfer of the trait by natural hybridization may produce hybrid progeny that are more aggressive or more difficult to control. These issues are not longer hypothetical, as at least seven groups of crops being engineered for pest resistance are known to have sexually compatible wild or weedy relatives in the US.
Major concerns about genetically modified turfgrasses include: - effect of gene products on non-target organisms - effect on competitiveness of the plant (fit in environment - serious weed) - accidental transfer of introduced genes (trespass) to other plants via cross-pollination - natural development of herbicide resistance in weedy populations
LAWS, REGULATIONS, POLICIES AND RESPONSIBILTY
Laws and requirements are aggressive regarding GMOs in US. If you are indeed the fortunate company to have GMO turfgrasses, have perfected the science, completed the patent and licenses and have freedom to operate in the marketplace you are required to meet regulatory requirements of the US government. Three agencies are primarily responsible for regulating biotechnology in United States includes the United States Department of Agriculture- Animal, Plant & Health Inspection Service (USDA-APIS), the Environmental Protection Agency (EPA) and the Food and Drug Administration (FDA). For Roundup® Ready or Finale® Resistant turfgrass or GMO herbicides this would require permits and approval from the USDA- APHIS. Bt genetic modification or other insecticides would require permits and approval from Environmental Protection Agency (EPA) and if the product is used for food/forage crop then Federal Drug Administration is the permitting and approval agency. There is some question about the potential lack of rigorousness and comprehensive regarding
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1Director
of Research, Cebeco International Seeds, Inc., Halsey, OR 97348 USA
Presentation @ A.G.C.S.A. in Melbourne, Australia June 5-8, 2000