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United States Department of Agriculture

Agricultural Research Service

Research Project: Fostering Coexistence: Industry-Driven Field and Landscape Research on Pollen Flow in Ge Alfalfa

Location: Vegetable and Forage Crops Production Research

2013 Annual Report


1a.Objectives (from AD-416):
Since 2007, the alfalfa industry has been working to develop coexistence strategies for genetically engineered Round Up Ready alfalfa (RRA). The National Alfalfa and Forage Alliance spearheaded efforts, and more recently, alfalfa seed producers have been working with AOSCA to develop an Alfalfa Seed Stewardship Program (ASSP). With the deregulation of RRA in February 2011, there is an urgent need to complete and implement coexistence strategies to protect the export seed market and other alfalfa markets that are sensitive to the adventitious presence (AP) of transgenic traits. Industry recognizes research is needed at the commercial scale to better understand pollen-mediated RRA transgene flow in the landscape. Extended conversations with alfalfa producers and breeding companies have led to the following objectives of our proposal: (1) to examine how leaf cutter and alkali bees transmit RRA across commercial seed fields and how that will impact proposed harvest strategies that separate seed for non AP- and AP- sensitive markets and to examine the persistence of RRA pollen in honeybee hives; (2) to characterize fitness parameters such as seed production, seed dormancy and viability, longevity in the seed bank, seedling establishment and plant persistence, in feral and feral-RRA hybrid alfalfa to determine how important and to what extent control strategies are required; (3) to track RRA transgene flow from RRA hay and seed production fields planted during the previous deregulation (seed fields were removed in 2007) into feral alfalfa to understand the role feral alfalfa plays as a transgene reservoir and vector for long distance transgene dispersal; (4) to study the transmission of the RR transgene from RRA hay fields to conventional seed fields to refine isolation distances by taking into account landscape variables.


1b.Approach (from AD-416):
This project will focus on the three main alfalfa seed and hay production areas in the Western United States: the Walla Walla valley and Columbia Basin in Washington, the Treasure Valley in Idaho and Oregon, and Fresno County in California. Monsanto has agreed to provide us with the locations of RRA hay and seed fields and will be giving us permission to use their event-specific PCR primers. We will be using greenhouse seedling assays and protein based, commercially available test strips to carry out qualitative tests for RRA presence in leaf, seed and hay sampling. Positive tests will be confirmed using PCR. Landscape genetics is a newly emerging field which provides powerful geostatistical tools to understand how gene flow is influenced by landscape variables. We will be using a landscape genetics approach to analyze transgene movement across the landscape. Since we want to generate information that has immediate relevance to industry’s efforts to establish coexistence strategies, our research will be focused at the commercial field and landscape level.


3.Progress Report:

This project identifies markers to screen alfalfa for resistance to environmental and biotic stresses which contributes to objective 1 of the in-house project. Glyphosate resistant alfalfa (RR-alfalfa) may become a weed and contribute to gene flow of the trait to non glyphosate resistant seed production fields. The fitness of RR-alfalfa may differ from that of alfalfa lacking the resistance gene, making it more or less able to survive and persist in the environment. Crosses between RR-alfalfa and feral alfalfa and between RR-alfalfa and Falcata alfalfa were completed to produce seed that will be used in subsequent fitness studies to compare seedling establishment and seed longevity of RR-alfalfa and RR-alfalfa crosses with feral alfalfa and Falcata. The effect of four auxin inhibitor herbicides on developing seed in RR-alfalfa plants was tested in a field trial. Dicamba, 2,4-D, triclopyr, and aminopyralid all reduced viable seed yield and the ability of seed to produce plants when applied to RR-alfalfa during seed maturation stage of growth (green developing seed pods). These herbicides could be useful in controlling seed production of feral RR-alfalfa plants and reducing the presence of the transgene in the wild.


Last Modified: 10/1/2014
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