Date of this Version
HORTSCIENCE, VOL. 34(4), JULY 1999
Recombinant DNA technology is a rapidly growing field in plant and animal breeding. This technology involves the transfer of pieces of DNA, or genes, regardless of the organisms involved or how they are related. Transformation procedures in plants were first developed for important crop and model plant systems. Although turfgrass management and production is one of the fastest growing areas of agriculture, genetic transformation of turfgrasses lags behind that of many other important crop plants. Turfgrasses are becoming more important primarily because of their association with the ever-increasing urban population. The size of the turfgrass seed market is second only to that of hybrid seed corn (Lee, 1996). However, much less is known about the genetics and physiology of turfgrasses. Many are polyploid, perennial, and/or outcrossing. These characteristics make them more difficult to study than many other crop plants. Use of transgenic technology in turfgrasses will likely follow as interest and corporate motivations allow.
Application of transgenic technology is virtually limitless. The past few years have seen a rapid increase in releases of transgenic plants. Between 1987 and 1997, 3330 permits and notifications were filed with the U.S. Dept. of Agriculture (USDA–APHIS, 1998) for release of genetically engineered organisms in the United States. Twenty-nine percent involved herbicide tolerance and 24% insect resistance. Compared with the major crop species, genetically engineered turfgrasses are uncommon. By Dec. 1998, 31 permits and notifications had been filed on creeping bentgrass (Agrostis stolonifera L.) and two notifications on Kentucky bluegrass (Poa pratensis L.) (USDA–APHIS, 1998). But as additional genes are identified and cloned, a myriad of traits will probably be introduced into the turfgrasses.
The first applications of transformation in turfgrasses were the incorporation of glufosinate [N,N-bis (phosphomethyl)glycine] resistance into creeping bentgrass (Lee et al., 1996; Liu et al., 1998), allowing application of a very effective nonselective herbicide to control unwanted weeds or other turfgrasses. In the future, recombinant DNA technology may be used to introduce other traits, such as insect resistance, disease resistance, and improved environmental stress tolerance.
Transformation technology may offer many economic and agronomic benefits that are difficult or impossible to achieve through traditional breeding techniques (Dale, 1993). Essential steps of recombinant DNA technology include identification of the gene of interest, its isolation (cloning), study of the gene’s function and regulation, and introduction of the gene and expression factors into cells (Marois et al., 1991). Finally, the traits must be evaluated in an agriculturally desirable genotype.