2011 Annual Report 1a.Objectives (from AD-416) To characterize the interaction of Xylella fastidiosa and sweet orange seed. 1b.Approach (from AD-416) This report documents research conducted under a Specific Cooperative Agreement between ARS and the University of Florida. Sweet orange seed infested with Xylella fastidiosa subsp. pauca, the pathogen that causes citrus variegated chlorosis disease will be collected in Sao Paulo, Brazil, and sent to Beltsville under permit. Samples of seed will be tested for the presence of the pathogen by PCR and isolation in vitro and electron microscopy. The remaining seed will be germinated and grown in the containment greenhouse under permit from USDA APHIS. Seedlings will be tested for the presence of the pathogen by PCR and electron microscopy and held for the development of symptoms. Tests will be carried out to determine if refrigeration can kill the pathogen. This will require the development of methods for PCR testing that distinguish between living and dead bacteria. 3.Progress Report Tests are being carried out to determine if refrigeration can kill the targeted pathogen of citrus. This will require the development of methods for PCR testing that distinguish between living and dead bacteria. The project was monitored by e-mail, phone conversations, and meetings with collaborators with the University of Florida.