Research Notes The Persistence of Engineered Agrobacterium tumefaciens in Agroinfected Plants. Nir Mogilner. S. Tolkowsky Laboratory, Agricultural Research Organization Volcani Center, Bet Dagan 50250 Israel. Dan Zutra(2), Ron Gafny(1), and Moshe Bar-Joseph(1). (1)S. Tolkowsky Laboratory and (2) Department of Plant Pathology, Agricultural Research Organization Volcani Center, Bet Dagan 50250 Israel.. MPMI 6:673-675. Accepted 20 May 1993. Copyright 1993 The American Phytopathological Society.

Several plant species, including tomato (Lycopersicon esculentum), Gynura aurantiaca, avocado (Persea americana), and grapefruit (Citrus paradisi) grafted on Troyer citrange (Poncirus trifoliata X C. sinensis) were "agroinfected" with Agrobacterium tumefaciens strain LBA-4404, carrying a mini-Ti plasmid with a dimeric cDNA of citrus exocortis viroid (CEVd). Extracts prepared from tissues of the agroinfected plants 38-90 days after inoculation were plated on selective media and found to contain large amounts of the engineered bacteria. These observations suggest the need for more stringent quarantine measures when handling A. tumefaciens cells harboring constructs for "agroinoculation" with plant viruses or viroids.