2010 Annual Report 1a.Objectives (from AD-416) The overall goal of this proposed research project is to create a system to assist identification, differentiation and fingerprinting of Ca. L. spp. 1. Analyze available phenotypic and genotypic data to estimate population diversity of Ca. L. spp.; 2. Characterize population diversity of Ca. L. spp. based on current genomic information by using a large number of Ca. L. spp. strains; and 3. Search for new phenomic and genomic information and their applications in Ca. L. spp. differentiation and fingerprinting. 1b.Approach (from AD-416) HLB bacterial DNA will be obtained through collaboration. In phase 1, an extensive literature database on HLB will be constructed. Specific emphasis will be on linking available phenotypic data to more recent genomic discoveries. The second phase is to explore the use of single nucleotide polymorphisms (SNPs) to cluster Ca. L. asiaticus strains. Correlations will be built to link SNPs to geographic and host origins, and other phenotypes such as symptomatology. Efforts will be made to isolate and characterize new DNA sequences from the Ca. L. asiaticus genome for SNP analysis. New data will be added to increase sensitivity and accuracy of the HLB pathogen fingerprinting system. Documents Trust with California Citrus Research Board. Log 34658. 3.Progress Report The agreement was established in support of Objective 1.C.1. of the in-house project, the goal being to determine the epidemiology of exotic, emerging, re-emerging, and invasive diseases in California, including, but not necessarily limited to, Xylella fastidiosa (Xf) caused diseases of horticultural, agronomic, and ornamental crops, and to determine genomic variations in Xf that are associated with pathogenicity. The goal was to evaluate the genomic diversity of an exotic and invasive bacterium, “Ca. L. asiaticus” associated with citrus Huanglongbing. DNA was collected from samples of “Ca. L. asiaticus” from two provinces in China and from the State of Florida in U. S. Bacterial strain variations were evaluated using partial sequences of a prophage and referenced to 16S rDNA gene sequence. At the prophage gene locus, all China strains were identical. The U. S. strains differed from the China strains in 9 single nucleotide positions. Utilizing the single nucleotide polymorphisms (SNPs) information, two primer sets were designed. One set was specific to China strains and the other set was specific to U. S. strains. In addition to the previous report based on a different genomic locus with tandem repeats, data from this study further reveal that China and U. S. populations of “Ca. L. asiaticus” are distinct.