Development and Validation of Sterility Systems for Trees, 2004 Paper Summit, Spring Technical & International Environmental Conference, (including Papermakers; Process Control, Electrical & Information; Product & Product Quality)

By providing an effective means of transgene containment, a robust sterility system could enable widespread use of genetically-modified trees with enhanced economic and environmental performance in forestry production systems. However, this likely prerequisite for many commercial uses of transgenic trees is paradoxically among the most difficult and time-consuming transgenic traits to demonstrate. Our approach is to develop and field test a number of single and combined sterility systems in parallel that could provide highly reliable forms of sterility. Most studies are focused on poplar, but also include work on eucalypts and sweetgum. We have developed early-flowering tree systems to speed testing, novel sterility transgenes, and large numbers of transgenic trees. Our laboratory has completed field-testing of transgenic trees with 10 different sterility-related transgenes. Currently, we have more than 1,000 trees in field trials with 18 different kinds of sterility-related transgenes, and work is underway to produce transgenic field trials with 30 additional kinds of sterility transgenes. Genetic mechanisms under evaluation include floral ablation via floral promoter::cytotoxin fusions, RNAi gene suppression of single and multiple genes, and dominant negative mutations.