2011 Annual Report 1a.Objectives (from AD-416) 1. Develop metabolic profiles of host responses to “Candidatus Liberibacter” associated diseases. 2. Identify genes involving defensive pathways to pathogen infections. 1b.Approach (from AD-416) 1. Use gas chromatography-mass spectrometry (GC/MS) and high perform liquid chromatography (HPLC) to develop citrus huanglongbing and potato zebra chip metabolic profiles. 2. Use matrix-assisted laser desorption/ionization mass spectrometry (MALDI-TOF-MS/MS)to identify candidate genes and pathways involving in defensive responses to Liberibacter infections. 3. Identified compounds and amino acid sequences will be compiled by querying the KEGG pathway databases to establish metabolic networks. 3.Progress Report This Specific Cooperative Agreement supports Objective 1.B of the parent project. The goal of the project is to characterize metabolic profiles of hosts in response to ‘Candidatus Liberibacter solanacearum’ infection and identify key pathways associated with the Zebra Chip (ZC) disease development. Healthy and ZC-diseased potato tubers were processed for comparative chemical profiling analyses by Gas Chromatography-Mass Spectrometry. Over 100 compounds were identified in both healthy and ZC potato tubers, and could be divided into three major groups: sugars, phenolic acids and free amino acids. In contrast to healthy potato tubers, ZC-affected potato tubers showed significant increases in glycine, serine, malic acid, fructose and galactose levels but a decrease in levels of propanetricarboxylic acid. ZC-affected tubers contained higher levels of reducing sugars, but lower levels of starch than those in healthy tubers, suggesting that ZC disease interferes with carbohydrate metabolism in tubers. Cooperating researchers cooperatively planned and conducted the research, and communicated regularly via several site visits and research discussions through email and telephone on a monthly basis.