Flower crop breeding programs have lagged behind food crop breeding programs in the identification and utilization of host resistance genes to viral, bacterial, and fungal pathogens, and insects. Consequently, disease management in flower production has relied heavily on chemical control. The extensive use of agrochemicals significantly increases growers' costs and contributes to environmental pollution. We have proposed to establish genetic transformation systems (via particle bombardment) for several major U.S. flower crops. Genetic engineering of flowers offers the opportunity of conferring transgene-mediated disease resistance to commercially-important phytopathogens to reduce both growers' costs (and thus increase their competitiveness in the international flower marketplace) and environmental damage (through less pesticide use). In Phase I, parameters for the efficient biolistic transformation of several major flower crops were established. These parameters for the efficient biolistic transformation of several major flower crops were established. These parameters included an evaluation of gene promoters, optimization of gene delivery, and identification of effective selection systems for recovering both dicotyledonous and monocotyledonous transgenic flowers. In Phase I, we identified synthetic lytic peptides with potent anti-fungal and/or antibacterial activities in vitro, and initiated gene synthesis for these peptides. In Phase II, recovery of transgenic plants will occur, including plants containing a variety of transgenes which should confer resistance to commercially- important pathogens. Based upon in vitro bioassays and greenhouse trials, the most promising resistance gene(s) will be introduced into horticulturally-accepted, proprietary varieties for commercial release.
Anticipated Results:The successful development of genetic transformation systems for several major U.S. flower crops will allow wide-scale genetic improvement of flowers. Most immediate, successful completion of Phases I and II will yield transgenic flowers which are resistant to several major phytopathogens. Additional traits which could eventually be effected through transgene expression include novel flower colors and floret shapes, modified plant habit, enhanced stress tolerance, and manipulation of gametogenesis. The floriculture market is characterized by diversity and novelty; genetic engineering offers an opportunity for designing flowers of unique appeal and benefit to the environment.