Citation: Callahan, A.M. 2004. Transgenic research at the Appalachian Fruit Research Station. In: Proceedings of the International Rosaceae Genome Mapping Conference, May 22-24, 2004, Clemson, South Carolina. Technical Abstract: Our research goal at the Appalachian Fruit Research Station (AFRS) is "to identify critical problems of temperate fruit production; develop the science, technology, and genetic base needed to maximize productivity and quality of fruit crops; and minimize the adverse effects of biotic and environmental factors on these crops." To this end, several research groups have developed a transgenic approach to both further the understanding of biological factors affecting fruit production as well as developing enhanced germplasm. Our emphasis is to improve disease resistance, ameliorate abiotic and biotic stress, enhance and preserve fruit quality, and improve the efficiency of production. The specific problems currently addressed using transgenic trees are viral resistance in Prunus, increased tolerance to abiotic stresses in apple, slower softening rates of Prunus, fire blight resistance in pears, dwarfing in pear, and nutrient uptake in apple. There are three tree fruits, apple, pear and plum, for which we have developed efficient Agrobacterium-based transformation systems. At present we have field plantings of plums containing the plum pox virus coat protein gene, or containing the antisense ACC oxidase gene, and pears and apples expressing lytic peptides. The only tree that is currently being considered for commercialization is a gene-silenced plum pox virus resistant plum, 'Honey Sweet'. With the future understanding of the genomics of Rosaceae, new genes can be targeted that will aid in our understanding and resolution of problems in fruit production and fruit quality.