An early-flowering genotype of<Emphasis Type="Italic">Populus</Emphasis>

Unlike herbaceous, annual crops, trees are not highly domesticated and, therefore, have wild relatives with which they are interfertile. They are also long-lived perennials that produce copious amounts of pollen and seed, which are often disseminated over considerable distances by the wind. Federal regulators have made it clear that before transgenic trees can be grown commercially in the U.S., it will be necessary to develop a strategy to mitigate the risk of transgene spread into the environment. One way to satisfy this requirement is to genetically engineer reproductive sterility. Because of its many useful attributes, poplar has becomethe model tree species for research community. However, because of its relatively long juvenile period, the development of a reliable sterility system for poplar is taking longer than expected. By having an early-flowering genotype of poplar, it will be possible to make much faster progress in our efforts to develop a reliable transgene-confinement system. We have identified a genotype ofPopulus alba that can be induced to flower within nine months of being regenerated.