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Abstract Detail



Ecological Section

Chang, Hsiaochi [1], Snow, Allison [1], Mutegi, Evans [1], Lewis, Emily [1], Miriti, Maria [1], Heaton, Emily [2].

Hybridization between Cultivated and Wild Switchgrass (Panicum virgatum) as a Function of Distance from Cultivar Field Trials: Implication for Biosafety Procedures.

Switchgrass (Panicum virgatum) is a native, perennial, warm-season grass that has been grown widely as a cultivar. It is also regarded as a leading model species for biofuel crops, and transgenic lines are likely to be developed for biofuel production. Gene flow from transgenic crops to wild relatives has been a concern of regulatory agencies, but little is known about the extent of pollen-mediated gene flow in switchgrass. To examine the extent of pollen dispersal from small-scale field trials, we established two field experiments with non-transgenic cultivar donors and wild recipients in 2011, at least 1 km away from other known switchgrass sources. For each experiment, a pair of tetraploid cultivated and wild switchgrass genets, each with distinct DNA SSR alleles, were divided into ~100 ramets and transplanted into experimental arrays. Each genet was self-incompatible, so any seeds were expected to come from crop-wild hybridization. Donors were planted together as one pollen source, and recipients were grouped at various distances and directions away from the donors. The experiment was conducted at two locations with slightly different designs: The Wilds (TW) in Cumberland, OH, with recipients located at 1 - 100m from the source, and Waterman Research Farm (WM) in Columbus, OH, with recipients at 1 - 130m. Florets from each recipient were harvested in the fall of 2011 and 2012 and subjected to x-ray analyses to calculate seed set (seeds per floret). DNA analyses were carried out on a subset of seeds, confirming that they were crop-wild hybrid, as expected. In both years and locations, flowering phenology overlapped and crop-wild hybrids were detected at all distances and most directions. In 2011, the frequency of hybrids decreased exponentially as a function of distance: 56.3% (TW) and 72.4% (WM) at 1m, 0.8% at 100m (TW) and 4.3% at 130m (WM). In 2012, when the plants were larger, the trend was similar to 2011 (TW: 30.96% and 1.62% at 1m and 100m, respectively; WM: 93.4% at 1m and 18.7% at 130m). We conclude that crop-wild hybridization in switchgrass could occur beyond 130m from relatively small donor plots (~100 plants). Therefore, a greater isolation distance would be required for future transgenic switchgrass field trials, if the goal is to prevent pollen-mediated gene flow to conspecific neighbors.

Broader Impacts:


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1 - The Ohio State University, Evolution, Ecology, and Organismal Biology, 318 W. 12th Ave., Columbus, OH, 43210
2 - Iowa State University, Agronomy, Agronomy Hall, Ames, IA, 50010

Keywords:
Biofuel
Switchgrass
Panicum virgatum
gene flow.

Presentation Type: Oral Paper:Papers for Sections
Session: 14
Location: Newberry/Riverside Hilton
Date: Monday, July 29th, 2013
Time: 4:15 PM
Number: 14009
Abstract ID:501
Candidate for Awards:Ecological Section Best Graduate Student Paper


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