2007 Annual Report 1a.Objectives (from AD-416) The objective of the collaborative research with China is to use locally infected citrus trees as sources of inoculum for cultivation of the etiological agent of HLB; Liberobacter asiaticum. 1b.Approach (from AD-416) The student will use available PCR primers along with additional sets developed at Ft. Detrick to identify high tittered tissues from which to obtain inoculum for testing various growth factors for cultivating the organism. Isolations of strains of HLB will be made from different areas around Chongqing. Dr. Schaad will visit annually to collect citrus seedlings and Periwinkle plants infected with HLB and meet with Prof. Wang and the student to review progress and discuss new approaches. The initial samples will be used for screening the specificity of additional primer set(s) to be developed at Ft. Detrick. The infected plants at Ft. Detrick will be used to provide a source of inoculum for confirming results obtained by the student. 3.Progress Report This final report serves to document research conducted under a reimbursable agreement between ARS and Chongqing University. Additional details of research can be found in the report of the parent project 1920-22000-029-00-D, Objective 2, Sub-objective 2b. Huanglongbing (HLB), a highly destructive disease of citrus, is caused by the non-culturable bacterium, Liberibacter asiaticus. To rapidly diagnose the disease we have developed a molecular (real-time PCR) assay in collaboration with Chongqing University, in China. Our Chinese collaborator, Professor Z. K. Wang, has sent samples of healthy leaves for use in testing the specificity of our real-time PCR primers and probe for L. asiaticus. Professor Wang has tested our primers and probe under field conditions and the results showed our primers and probe were specific to L. asiaticus. He will continue collaborating with us on HLB by sending a PhD student with full China funding to work one year at Ft. Detrick on characterizing, identification, and culturing the HLB bacterium. Progress on this project was monitored by e-mails with the cooperator. Project ends September 30, 2007.