Abstract
Despite growing concern about transgenes escaping from fields, few studies have analysed the genetic diversity of crops in an agroecosystem over several years. Accurate information about the dynamics and relationship of the genetic diversity of crops in an agroecosystem is essential for risk assessment and policies concerning the containment of genetically modified crops and their coexistence with crops grown by conventional practices. Here, we analysed the genetic diversity of oilseed rape plants from fields and feral populations over 4 years in an agricultural landscape of 41 km2. We used exact compatibility and maximum likelihood assignment methods to assign these plants to cultivars. Even pure lines and hybrid cultivar seed lots contained several genotypes. The cultivar diversity in fields reflected the conventional view of agroecosystems quite well: that is, there was a succession of cultivars, some grown for longer than others because of their good performance, some used for one year and then abandoned, and others gradually adopted. Three types of field emerged: fields sown with a single cultivar, fields sown with two cultivars, and unassigned fields (too many cultivars or unassigned plants to reliably assign the field). Field plant diversity was higher than expected, indicating the persistence of cultivars that were grown for only one year. The cultivar composition of feral populations was similar to that of field plants, with an increasing number of cultivars each year. By using genetic tools, we found a link between the cultivars of field plants in a particular year and the cultivars of feral population plants in the following year. Feral populations on road verges were more diverse than those on path verges. All of these findings are discussed in terms of their consequences in the context of coexistence with genetically modified crops.
Highlights
The introduction of genetically modified (GM) plants in agroecosystems formed the starting point of the study of gene flows in human-shaped environments [1]
Despite growing concern about transgenes escaping from fields, few studies have analysed the genetic diversity of crops in an agroecosystem over several years
Accurate information about the dynamics and relationship of the genetic diversity of crops in an agroecosystem is essential for risk assessment and policies concerning the containment of genetically modified crops and their coexistence with crops grown by conventional practices
Summary
The introduction of genetically modified (GM) plants in agroecosystems formed the starting point of the study of gene flows in human-shaped environments [1]. Agroecosystem and Genetic Diversity of Rapeseed in agroecosystems and raises concerns about GM contaminations through the link between cultivar seeds and harvests [2]. Oilseed rape (OSR) is a model plant for studying gene flow at the landscape scale. OSR is an economically important crop in North America and Europe. GM OSR is mainly cultivated in North America, but its cultivation in Europe is a matter of controversy. OSR exhibits traits that suggest that it was recently domesticated [3]: partial autogamy, seeds with a strong capacity for dehiscence before harvest and significant secondary dormancy
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