Reuter Hauke, Menzel Gertrud, Pehlke Hendrik, Breckling Broder
Department of General and Theoretical Ecology, Centre for Environmental Research and Sustainable Technology (UFT), University of Bremen, P. O. Box 330440, 28334 Bremen, Germany.
Environ Sci Pollut Res Int. 2008 Oct;15(7):529-35. doi: 10.1007/s11356-008-0049-5. Epub 2008 Oct 7.
BACKGROUND, AIM AND SCOPE: Transgenic oilseed rape (Brassica napus L.; OSR) is estimated to be environmentally and economically problematic because volunteers and ferals occur frequently and because of its hybridisation potential with several wild and weedy species. A proposed mitigation strategy aims to reduce survival, in particular in conventional OSR crops, by coupling the transgenic target modification with a dwarfing gene to reduce competitive fitness. Our study allowed us to access potential ecological implications of this strategy.
On a large scale (>500 km(2)), we recorded phenological and population parameters of oilseed rape plants for several years in rural and urban areas of Northern Germany (Bremen and surroundings). The characterising parameter were analysed for differences between wild and cultivated plants.
In rural areas, occurrences of feral and volunteer OSR together had an average density of 1.19 populations per square kilometre, in contrast to urban areas where we found 1.68 feral populations per square kilometre on average. Throughout the survey, the vegetation cover at the locations with feral OSR ranged from less than 10% to 100%. Our investigations gave clear empirical evidence that feral OSR was, on average, at least 41% smaller than cultivated OSR, independent of phenological state after onset of flowering.
The findings can be interpreted as phenotypic adaptation of feral OSR plants. Therefore, it must be asked whether dwarfing could be interpreted as an improvement of pre-adaptation to feral environments. In most of the sites where feral plants occurred, germination and establishment were in locations with disturbed vegetation cover, allowing initial growth without competition. Unless feral establishment of genetically modified dwarfed traits are specifically studied, it would not be safe to assume that the mitigation strategy of dwarfing also reduces dispersal in feral environments.
With respect to OSR, we argue that the proposed mitigation approach could increase escape and persistence of transgene varieties rather than reducing them. We conclude that the development of effective hazard mitigation measures in the risk evaluation of genetically modified organisms requires thorough theoretical and empirical ecological analyses rather than assumptions about abstract fitness categories that apply only in parts of the environment where the plant can occur.
背景、目的与范围：据估计，转基因油菜（甘蓝型油菜；OSR）存在环境和经济问题，因为其自生苗和野生植株频繁出现，且具有与多种野生及杂草物种杂交的潜力。一项提议的缓解策略旨在通过将转基因目标修饰与矮化基因相结合以降低竞争适应性，从而减少（尤其是常规OSR作物中的）存活植株数量。我们的研究使我们能够了解该策略可能产生的生态影响。
在德国北部（不来梅及其周边地区）的农村和城市地区，我们在数年时间里大规模（超过500平方公里）记录了油菜植株的物候和种群参数。分析了表征参数以找出野生植株与栽培植株之间的差异。
在农村地区，野生和自生OSR的出现频率平均为每平方公里1.19个种群，而在城市地区，我们平均每平方公里发现1.68个野生种群。在整个调查过程中，有野生OSR的地点的植被覆盖度从不到10%到100%不等。我们的调查提供了明确的实证证据，即野生OSR平均比栽培OSR至少小41%，与开花后物候状态无关。
这些发现可被解释为野生OSR植株的表型适应。因此，必须要问的是，矮化是否可被解释为对野生环境预适应的改善。在大多数有野生植株出现的地点，发芽和定殖发生在植被覆盖度受到干扰的地方，使得初始生长没有竞争。除非专门研究转基因矮化性状的野生定殖情况，否则假设矮化缓解策略也能减少在野生环境中的扩散是不安全的。
关于OSR，我们认为提议的缓解方法可能会增加转基因品种的逃逸和持久性，而不是减少它们。我们得出结论，在转基因生物风险评估中制定有效的危害缓解措施需要全面的理论和实证生态分析，而不是对仅适用于植物可能出现的部分环境的抽象适应性类别进行假设。
