Tumorigenic Agrobacterium sp. Isolated from Weeping Fig in Spain

Abstract

Agrobacterium-like colonies were recovered onto Roy-Sasser's medium from a young tumor (4 cm in diameter) on the stem of weeping fig (Ficus benjamina L.), 10 cm from the crown. The galled plant was collected in 1999 from a garden center in Valencia, Spain. After colony purification and tomato and weeping fig plant inoculations, one nonpathogenic and five Agrobacterium isolates that were tumorigenic in both plant species were characterized. On the basis of biovar classification tests, the nonpathogenic isolate was identified as belonging to biovar 1 of Agrobacterium (now called A. tumefaciens), whereas the tumorigenic isolates could not be assigned to any of the known Agrobacterium biovars. The isolates were positive for oxidase, growth in 2% NaCl, production of alkali from l-tartaric acid, and production of acid from mannitol-CaCO3 and negative for 3-ketolactose production, growth and pigmentation in ferric ammonium citrate, growth at 35°C, citrate utilization, acid production from sucrose and melezitose, and alkali production from malonic acid. Nopaline was the unique opine found in galls induced in weeping fig plants inoculated with the pathogenic isolates. Moreover, all isolates utilize the opine nopaline, but not octopine, manopine, agropine, chrysopine, cucumopine, or mikimopine. They were susceptible to agrocin 84 produced by strain K84. Heat-treated bacterial suspensions of these isolates yielded the expected amplification product using polymerase chain reaction (PCR) with the FGPtmr530/FGPtmr701′ primers pair from the tmr gene (3). Aerial gall disease was first reported on F. benjamina in Florida (1), and the isolated agrobacteria belongs to a new species named A. larrymoorei (2). Later, tumorigenic agrobacteria from weeping fig galls were isolated in Italy and the Netherlands (4). Our data suggest that the tumorigenic strains isolated in Spain differ greatly from those first described in the United States (1) on the basis of alkali production from l-tartaric acid, chrysopine detection on tumors, susceptibility to agrocin 84, and tmr amplification, but they might be similar to some of the Italian isolates (4). To our knowledge, this is the first report of isolation of tumorigenic Agrobacterium sp. from F. benjamina L. in Spain. References: (1) H. Bouzar et al. Appl. Environ. Microbiol. 61:65, 1995. (2) H. Bouzar and J. B. Jones. Int. J. Syst. Evol. Microbiol. 51:1023. 2001. (3) X. Nesme et al. Pages 47–50 in: Endocytobiology IV. P. Nardon et al. eds. INRA, France, 1989. (4) A. Zoina et al. Plant Pathol. 50:620, 2001.