2007 Annual Report 1a.Objectives (from AD-416) The objective of this cooperative research is to determine the biological basis for the continued problems with Impatiens Necrotic Spot Virus in floral crops. 1b.Approach (from AD-416) Investigate the population biology of Impatiens Necrotic Spot Virus in floral crops by comparing current populations with historical collections maintained by the PI, identify plant and insect hosts in the cropping systems and then determine which are responsible for the maintenance of the virus in the system. 3.Progress Report This report serves to document research conducted under a specific cooperative agreement between ARS and North Carolina State University. It was recently transferred to Fort Pierce from North Carolina and now falls under the parent CRIS 6618-22000-034-00D, Domestic, Exotic and Emerging Diseases of Citrus, Vegetables and Ornamentals (DEED). We have continued to characterize the population diversity of Impatiens necrotic spot virus (INSV) to extend our comprehensive system for attribution of Tomato spotted wilt virus isolates to INSV. We have refined the optimal sequence alignment (OSA) fragments of 48 isolates from a variety of host plants originating from: Asia, North America, South America, Europe, and New Zealand, which were obtained through our collaborators. OSA fragments corresponding to the N gene on the S RNA, the NSm gene from the M RNA, and the RNA-dependent RNA polymerase gene on the L RNA have been sequenced and analyzed together with sequences available from public data banks. The phylogeny of the N gene OSA fragments has been determined. Analysis of the NSm and the RdRp is in process. Preliminary results with the INSV isolates based on Hudson’s tests revealed five genetically distinct groups with high statistical significance: three in North America (California, New York, and North Carolina) and one each originating in Japan/Asia and Europe. Isolates from South America were not separated from isolates from North America. We have begun to investigate the epidemiology of INSV in floral crops with emphasis on host and vector mediated changes in virus populations. During the past year we have collaborated with two operations in California. We hope to expand this to additional operations on the East coast this year. This research will be continued in the next phase of the research and will provide key information on why INSV continues to persist in the industry. Cooperator’s performance was monitored by multiple phone and email discussions of program goals and accomplishments. Additionally, Cooperator and ADODR met during the American Phytopathological Society meeting in July 2007 to further discuss project. 4.Accomplishments Impatiens necrotic spot virus (INSV) is one of the most frequently detected viruses in ornamental crops. We have developed an exhaustive database for a related virus, Tomato spotted wilt virus (TSWV), and used analysis of its sequence and population dynamics to demonstrate phylo-geographic relationships for TSWV. We have now developed a database containing sufficient numbers of INSV sequences to enable to testing for phylo-geographical relationships with this virus. The predicted outcome of this accomplishment is the ability to assign attribution to outbreaks, test for mechanisms of genetic variation such as reassortment, and apply this knowledge to subsequent studies of the epidemiology of this virus. Addresses National Program Component 2 (Biology, ecology, epidemiology, and spread of plant pathogens and their relationships with hosts and vectors).