A new method for evaluating flowering synchrony to support the temporal isolation of genetically modified crops from their wild relatives

Modeling the flowering sensitivity of five accessions of wild soybean (Glycine soja) to temperature and photoperiod, and its latitudinal cline

The introgression from genetically modified soybean (Glycine max (L)) to wild soybean (Glycine soja Sieb. et Zucc.) could be threat the genetic diversity of wild soybean. Flowering synchrony is essential to the occurrence of outcrossing, but the flowering phenology of wild soybean is less well researched than that of cultivated soybean. We developed models to predict flowering initiation of wild soybean, based on the flowering initiation dates of wild soybean five accessions from different latitudes (31.4°N to 42.6°N) in growth chambers in which temperature and day length varied. Our proposed models predicted the flowering initiation date of wild soybean in the natural habitat well; the averaged difference from observed date in 5 areas was -1.8 days (-8 to +5). In the long day condition, there was a clear latitudinal cline of photoperiodic sensitivity throughout Japan. Accessions in southern part of Japan archipelago required higher temperature even under the short-day conditions and northern accessions were less-sensitive to long-day conditions. Our result showed the possibility of predicting the flowering initiation of wild soybean, corresponding to latitudes.

Likelihood assessment for gene flow of transgenes from imported genetically modified soybean (Glycine max (L.) Merr.) to wild soybean (Glycine soja Seib. et Zucc.) in Japan as a component of environmental risk assessment

Environmental risk assessment is required for genetically modified (GM) crops before their import into Japan. Annual roadside monitoring along transportation routes from ports to processing facilities for GM soybean (Glycine max (L.) Merr.) have been requested as a condition of import only approval because of lack of information on the likelihood of persistence of imported GM soybean for food, feed and processing and the potential for transfer of transgenes into wild soybean (Glycine soja Seib. et Zucc.) through gene flow under the Japanese environment. The survey of soybean seeds, plants and wild soybean populations were conducted along transportation routes from unloading ports to processing facilities that provided data to help quantify actual exposure. The survey indicated that the opportunities for co-existence and subsequent crossing between wild soybean populations and imported soybean are highly unlikely. Together the survey results and the comprehensive literature review demonstrated low exposure of imported GM soybean used for food, feed and processing in Japan. This evaluation of exposure level is not specific to particular GM soybean event but can apply to any GM soybean traits used for food, feed and processing if their weediness or invasiveness are the same as those of the conventional soybean.