Plant Fitness Assessment for Wild Relatives of Insect Resistant Bt-Crops

摘要

When field tests of transgenic plants are precluded by practical containment concerns, manipulative experiments can detect potential consequences of crop-wild gene flow. Using topical sprays of bacterialBacillus thuringiensislarvicide (Bt) and larval additions, we measured fitness effects of reduced herbivory onBrassica rapa(wild mustard) andRaphanus sativus(wild radish). These species represent different life histories among the potential recipients of Bt transgenes from Bt cole crops in the US and Asia, for which rare spontaneous crosses are expected under high exposure. Protected wild radish and wild mustard seedlings had approximately half the herbivore damage of exposed plants and 55% lower seedling mortality, resulting in 27% greater reproductive success, 14-day longer life-spans, and 118% more seeds, on average. Seed addition experiments in microcosms andin situindicated that wild radish was more likely to spread than wild mustard in coastal grasslands.