Genetic modification for improvement of Populus

Species of the genus Populus (poplars and aspens) are widely grown in the temperate regions of the Northern Hemisphere. Hybridization of Populus through conventional breeding has been ongoing for more than seventy years in scientifically-based programs. This hybridization has yielded a large number of "Hybrid Populus" with improved qualitative and quantitative traits. However, the progress in tree improvement through conventional breeding is relatively slow and is limited to traits controlled by alleles naturally present in Populus germplasm. The techniques of genetic engineering have provided tools to accelerate and diversify the genetic manipulation of Populus by bypassing the sexual cycle and directly adding novel genes from heterologous sources to the poplar genome. A few example, include, but are not limited to, enhancing insect resistance and herbicide tolerance, accelerating flowering and introducing male sterility, allowing and improving the use of poplars in phytoremediation, and modifying wood quality by manipulating the lignin biosynthesis pathway. A novel use of hybrid poplars as plant factories to produce high value recombinant proteins and biomolecules through molecular farming is a high priority area for new research.