GM Crop Database

Database Product Description

ASR368 (SMG-368ØØ-2)
Host Organism
Agrostis stolonifera (Creeping Bentgrass)
Trait
Herbicide tolerant, glyphosate.
Trait Introduction
Microparticle bombardment of plant cells or tissue
Proposed Use

Production of turf in golf courses. Incidental usage in livestock feed.

Product Developer
Scotts Seeds

Summary of Regulatory Approvals

Country Food Feed Environment Notes
United States 2003 2003 2017

Abstract Collapse

Creeping bentgrass (Agrostis stolonifera L.) is a perennial grass (Familiy Poaceae) grown in pastures, as a turfgrass in golf courses, and also for revegetation and soil stabilization. It is a cool-season grass that has become naturalized in many temperate and cold regions of the world. It is considered a native grass in the United States and Canada; however, some populations have become naturalized from sources native to Eurasia.

The success of creeping bentgrass as a pasture grass, turfgrass, and soil stabilizer is due to its growth habit. Creeping bentgrass is a prostrate grass, forming numerous stolons that spread along the ground. Creeping bentgrass reproduces by seed, but also vegetatively by the formation of stolons. New tillers grow from meristematic points on the nodes of the stolons; from each new tiller there is the formation of new stolons. This vegetative growth results in the formation of sod, i.e., a fairly continuous mat of vegetation. Creeping bentgrass is resistant to grazing and mowing since the growing points of the tillers and stolons are near the ground. Grazing and mowing suppresses the apical dominance of the main culm (stem), which stimulates the formation of new stolons at the base. Fibrous roots grow from each new tiller; these roots stabilize and add biomass to the soil.

Grasses grown for turf, especially in golf courses, are intensively managed. Part of this management includes the use of herbicides for the establishment and maintenance of the turf. Creeping bentgrass is used in putting greens, tees, and fairways. Roundup Ready® creeping bentgrass (ASR368) was developed to allow the use of glyphosate, the active ingredient in the herbicide Roundup®, as a weed control option in the production of creeping bentgrass in golf courses. This genetically engineered grass contains a novel form of the plant enzyme 5-enolpyruvylshikimate-3-phosphate synthase (EPSPS). This enzyme allows ASR368 to survive an otherwise lethal application of glyphosate. The EPSPS gene introduced into ASR368 was isolated from a strain of the common soil bacterium Agrobacterium tumefaciens strain CP4; the novel form of the EPSPS enzyme produced by this gene is tolerant to glyphosate.

The EPSPS enzyme is part of the shikimate pathway, an important biochemical pathway in plants involved in the production of aromatic amino acids and other aromatic compounds. When conventional plants are treated with glyphosate, the plants cannot produce the aromatic amino acids needed for growth and survival. EPSPS is present in all plants, bacteria, and fungi. It is not present in animals, since these organisms are unable to synthesize their own aromatic amino acids. Because the aromatic amino acid pathway is not present in mammals, birds, or aquatic life forms, glyphosate has little, if any, toxicity for these organisms. The EPSPS enzyme is naturally present in foods derived from plant and microbial sources. ASR368 creeping bentgrass was developed by introducing two CP4 EPSPS genes into the A. stolonifera line B9906R using microprojectile bombardment (i.e. , particle acceleration, biolistics transformation).

The livestock feed safety of ASR368 creeping bentgrass was based on: a history of safe consumption of the CP4 EPSPS enzyme in previously approved glyphosate tolerant crops; the lack of toxicity or allergenicity of CP4 EPSPS; and by direct laboratory and safety studies of the CP4 EPSPS protein. The nutritional equivalence and wholesomeness of ASR368 compared to the nonmodified parental line was demonstrated by the compositional analysis of the forage, including proximates (crude protein, crude fat, crude fibre, ash, and moisture), acid detergent fibre, neutral detergent fibre, and minerals.