Long and Medium Term Research: Exchange of Genetic Material Among Plant Viral RNAs. This award recommendation is made under the Program for Long and Medium-Term Research at Foreign Centers of Excellence. The program is designed to enable young U.S. scientists and engineers to conduct long-term research abroad at research institutions of proven excellence. Awards provide opportunities for the conduct of joint research and the use of unique or complementary facilities, expertise and experimental conditions in foreign countries. The award will support a ten month research visit by Dr. Keith L. Perry and Dr. William E. Fry of Cornell University - State, Department of Plant Pathology, with Dr. Richard Francki, Waite Agricultural Research Institute, University of Adelaide, South Australia. While plant RNA viruses exhibit an extraordinary degree of variability with respect to host range and induced host range responses, little information is available on what mechanisms lead to this diversity. The researchers propose to address this variability among plant viral RNAs through a study of recombination (the exchange of sequence domains between two RNAs) and pseudorecom- bination (the reassortment of intact genomic RNAs from multicomponent viruses), assessing the role of recombination and pseudorecombination as well as point mutations in the evolution of plant viruses and the generation of new disease agents. The researchers seek: (1) to isolate recombinant and pseudorecombinant viruses and obtain an estimate for the minimum frequency of their occurrence in mixed virus infections; (2) to assess the competitive fitness of recombinant viruses; and (3) to make a detailed molecular characteri- zation of recombinants to determine if recombination is homologous, if hotspots for recombination exist, and if crossover points occur intragenically or within non-translated RNA domains. The experi- mental system consists of (1) a group of tripartite RNA viruses, the cucumoviruses; (2) their aphid vectors; and (3) a wide host range of plants in which virus-plant interactions can be observed and manipulated. The award recommendation provides funds to cover, as appropriate, international travel, local travel abroad, stipend, dependents' allowance, if applicable, and a flat administrative allowance of $250.00 for the U.S. home institution.
