1a.Objectives (from AD-416):
To characterize the interaction of Xylella fastidiosa and sweet orange seed.
1b.Approach (from AD-416):
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.
Sweet orange seed was obtained from Brazil and germinated, grown in a greenhouse and tested for the presence of Xylella fastidiosa by isolation and by DNA based methods.