Plant Science Presentations and Proceedings

Ecological Risk Assessment of Switchgrass (Panicum virgatum) in Connecticut.

Carol Auer et al. — Wed, 13 May 2009 11:45:32 PDT

A native of North America, switchgrass (Panicum virgatum) is a hardy rhizomatous perennial with an expansive range. The U.S. Department of Energy has identified switchgrass as a promising biofuel crop for low-input agriculture and marginal lands (Fig. 1). This has prompted research on improvement through genetic modification (GM). Before any new GM crop can be released, regulators must evaluate not only the modified plants, but also potential negative impacts to the environment. For example, hybridization between closely-related species could result in the transfer of GM traits to relatives (gene flow) creating new weeds or invasives. The objective of this research program is to assess the potential for gene flow and ecological risks from the future release of GM switchgrasses in New England.

If hybrids go wrong: Assessing potential environmental risk from release of herbicide-resistant creeping bentgrass (Agrostis).

Carol Auer et al. — Fri, 08 May 2009 11:09:42 PDT

Genetically-modified (GM) plants need to be assessed for their benefits and risks before they are released into the environment. At present, GM grasses are being developed to improve sports turf and biofuels crops (e.g. switchgrass). How will genetic engineering of perennial grasses alter the distribution of these grasses in natural areas and managed landscapes? Can we use research data to predict future gene flow, weediness, or invasion? These are some of the important questions in ecological risk assessment of GM perennial grasses. We have initiated five research projects to characterize gene flow and potential ecological risk from herbicide-resistant (HR) creeping bentgrass. Creeping bentgrass (Agrostis stolonifera) is a common, non-native turfgrass that is a weed and hybridizes with other Agrostis species. At present, USDA is considering an application to allow commercialization of genetically-modified herbicide-resistant (HR) creeping bentgrass. If approved, there is a significant probability that the transgenic HR trait would move into feral bentgrass populations and this could create environmental hazards over various temporal and spatial scales. How would species distribution be altered if these weedy grasses became resistant to the popular herbicide glyphosate? In this poster we provide a progress report on two research projects: 1) habitat suitability modeling (HSM) to predict the presence of bentgrasses at the landscape scale, and 2) gap colonization studies in natural and agricultural sites to quantify changes in bentgrass fitness under herbicide selection pressure.

Drought and Salinity Tolerance in Common Agrostis Species.

Carol Auer et al. — Fri, 08 May 2009 10:21:31 PDT

Our research examines plant gene flow and the impacts from environmental release of genetically-modified plants. Plant gene flow is a natural process that occurs when pollen from one plant lands on the flower of another plant and produces a hybrid offspring. Gene flow can produce hybrid offspring with new traits that could change the ability of the plant to survive and spread. If hybrid offspring have some advantage in the environment, they could become invasive and/or affect other components of our ecosystems. In the near future, the federal government may approve the use of a genetically engineered herbicide-resistant (HR) Agrostis stolonifera. A. stolonifera (creeping bentgrass) is a common non-native grass that inhabits a myriad of environments. It is also known to hybridize with four non-native bentgrass relatives in Connecticut. If the HR A. stolonifera is used, the gene is likely to escape into feral and cultivated bentgrass populations. Studies are needed to quantify the potential impact the HR trait could have on the environment. This study uses greenhouse experiments to characterize stress tolerance in four common, non-native, feral Agrostis species. The differences in stress tolerance that have been observed act as a proxy for adaptability and weediness. Changes in adaptability and weediness may become important factors in future gene flow and escape of the transgene.

Characterizing Bentgrass Distribution with Spatial and Biological Data To Support Ecological Risk Assessment in Connecticut

Carol Auer et al. — Fri, 08 May 2009 10:19:11 PDT

Genetically-modified (GM) crops must be assessed before they are released into the environment. Our research examines the potential for gene flow and negative ecological impacts from the release of GM turfgrasses. Gene flow can produce hybrid offspring with transgenes and novel traits that could change the ability of the plant to survive and spread. If hybrid offspring have an advantage in the environment, they could become invasive and/or affect other components of our ecosystems. Creeping bentgrass (Agrostis stolonifera) is a common, non-native turfgrass that is a weed and could hybridize with other Agrostis species. At present, United States Department of Agriculture (USDA) is considering an application to allow commercialization of genetically-modified herbicide-resistant (HR) creeping bentgrass. If approved, there is a probability that the transgenic HR trait would move into feral bentgrass populations and create environmental hazards over various temporal and spatial scales. This poster reports on the development of the Habitat Suitability Model using botanical surveys, ecological variables and GIS data for a golf course study site in central Connecticut. It has been concluded that many feral bentgrass populations exist near the golf course site, these bentgrass populations overlap with 11 state-listed species, and bentgrasses frequently co-exist with invasive plants. Therefore, the escape of HR creeping bentgrass could produce undesirable outcomes such as difficulty in invasive plant or weed management, genetic pollution, increased bentgrass weediness, and loss of biodiversity.

When hybrids go wrong. How hybridization can create invasive species.

Carol Auer et al. — Fri, 08 May 2009 08:50:21 PDT

Gene flow is the movement of genes from one plant population to another. Gene flow is a natural process and a part of plant evolution. There are two ways for gene flow to occur in plants. The first is through sexual reproduction – pollen lands on a flower and a viable seed develops. The second method is through dispersal of seeds and/or vegetative plant parts (e.g. stolons, rhizomes). Gene flow can produce hybrid offspring with an increased or decreased ability to survive in the landscape. If hybrid offspring have some advantage in the environment, they could become invasive. This poster shows two examples of gene flow in plants and the potential for environmental damage.

Integration of GIS and Bentgrass Ecology for Ecological Risk Assessment.

Carol Auer et al. — Fri, 08 May 2009 08:46:30 PDT

All new technologies carry both benefits and risks. Genetically-modified plants must be assessed before they are released into the environment. Our research examines plant gene flow and the potential impacts from environmental release of genetically-modified plants. Plant gene flow is a natural process that occurs when pollen from one plant lands on the flower of another plant and produces a hybrid offspring. Gene flow can produce hybrid offspring with new traits that could change the ability of the plant to survive and spread. If hybrid offspring have some advantage in the environment, they could become invasive and/or affect other components of our ecosystems. In the near future, the federal government may approve herbicide-resistant (HR) creeping bentgrass (Agrostis stolonifera), a common, non-native grass used on golf courses. We are using plant ecology coupled with spatial information to gain an understanding of the possible risks associated with escape of the HR trait. Using spatial information and ecology, a habitat suitability model (HSM) is being made to help predict where bentgrasses exist and where management problems may occur.

Decomposition Rates and Nitrogen Release of Turf Grass Clippings

Kelly L. Kopp et al. — Thu, 15 Feb 2007 10:05:27 PST

Decomposition rates and N release patterns of turfgrass clippings from lawns are not well understood. Litter bags containing clippings were inserted into the thatch layer of a coolseason turf. The experiment was arranged as a 2 × 4 factorial in a randomized complete block design with three replicates. Treatments included four rates of N fertilizer (0, 98, 196, and 392 kg N ha^-1 yr^-1) and two clipping treatments (returned vs. removed). Litter bags were removed periodically over the growing season and samples were analyzed for biomass, N and C concentrations, and C:N ratio on an ash-free basis. Percentage N loss from the clippings after 16 weeks ranged from 88% to 93% at the 0 and 392 kg N ha^-1 rates, respectively, and from 86% to 94% when clippings were removed (CRM) or returned (CRT), respectively. Percentage C loss from the clippings ranged from 94% to 95% at the 0 and 392 kg N ha^-1 rates, respectively, and from 92% to 96% with CRM and CRT, respectively. Cumulative N release was similar across N fertilization rates, (ranging from 131 g N kg^-1 to 135 g N kg^-1 tissue) but was higher for CRT (151 g N kg^-1 tissue) than for CRM (128 g N kg^-1 tissue). Grass clippings decomposed rapidly and released N quickly when returned to the turf thatch layer. This indicates the potential for reduced N fertilization when clippings are returned. Such rapid decomposition also suggests that the contribution of grass clippings to thatch development is negligible.

Could a Gene for Herbicide Resistance Alter Distribution and Management of Bentgrass Populations?

Carol Auer et al. — Tue, 15 Aug 2006 12:09:34 PDT

Biogeography of Bentgrasses (Agrostis) in Connecticut

Carol Auer — Tue, 15 Aug 2006 12:03:24 PDT