Author : Snow, Allison

Summary : In the short-term, the first types of transgenic sunflowers to be released may pose few environmental risks. To be confident of this, we recommend that risks associated with pest resistance transgenes be evaluated as outlined above. At present, the most urgent need for further research is an evaluation of how transgenes for insect resistance could affect the abundance of wild populations. A worst case scenario would be that transgenic wild plants would produce 20-30% more seeds per plant, perhaps leading to larger pools of dormant seeds in the soil and more successful colonization of disturbed sites in natural and agricultural areas, thereby exacerbating existing weed problems. Alternatively, empirical studies may show that effects of transgenic pest-resistance traits are negligible, especially in the case of narrow-spectrum Bt transgenes. We recommend a combination of baseline surveys, field experiments, and modeling of metapopulation dynamics to permit informed assessments of the risk associated with novel transgenes. Taking a longer-term view, we expect that commercial sunflower hybrids with strong resistance to hervibores, diseases, herbicides, and even drought-or frost-induced stress could be developed for commercialization. Multiple transgenes could be "stacked" within the same cultivar, perhaps as tightly linked traits that would be transferred together or by simply entering wild populations as separate transformation events. The combined effects of multiple fitness-related transgenes on wild/weed populations should be carefully considered prior to their commercial release to avoid undesirable increases in the abundance of weedy sunflowers.