A model to predict the frequency of integration of fitness-related QTLs from cultivated to wild soybean
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With the proliferation of genetically modified (GM) products and the almost exponential growth of land use for GM crops, there is a growing need to develop quantitative approaches to estimating the risk of escape of transgenes into wild populations of crop relatives by natural hybridization. We assessed the risk of transgene escape by constructing a population genetic model based on information on fitness-related QTLs obtained from an F 2 population of wild soybean G. soja × cultivated soybean Glycine max. Simulation started with ten F 1 and 990 wild soybeans reproducing by selfing or outcrossing. Seed production was determined from the genetic effects of two QTLs for number of seeds (SN). Each seed survived winter according to the maternal genotype at three QTLs for winter survival (WS). We assumed that one neutral transgene was inserted at various sites and calculated its extinction rate. The presence of G. max alleles at SN and WS QTLs significantly decreased the probability of introgression of the neutral transgene at all insertion sites equally. The presence of G. max alleles at WS QTLs lowered the risk more than their presence at SN QTLs. Although most model studies have concentrated only on genotypic effects of transgenes, we show that the presence of fitness-related domestication genes has a large effect on the risk of transgene escape. Our model offers the advantage of considering the effects of both domestication genes and a transgene, and they can be widely applied to other wild × crop relative complexes.
KeywordsGlycine max Hybridization Linkage Quantitative trait loci Simulation model Transgene
We would like to give special thanks to Dr. H. Yano and Mr. N. Matsuoka of the Agricultural Research Center for the Western Region for their support in the field. This study was supported by the Research Fund for “Assurance of Safe Use of Genetically Modified Organisms” from the Ministry of Agriculture, Forestry and Fisheries of Japan and the Global Environment Research Fund of the Ministry of the Environment of Japan (FY2003–2005).
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