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Unformatted text preview: Vol. 57,No. 9 APPLIED AND ENVIRONMENTAL MICROBIOLOGY, Sept.1991,p. 2468-2472 0099-2240/91/092468-05$02.00/0 Copyright 1991, American SocietyforMicrobiology Characterization of an Unusual New Agrobacterium tumefaciens Strainfrom Chrysanthemum morifolium Ramt ARLA L. BUSHt* AND STEVEN G. PUEPPKE Department ofPlant Pathology, University ofMissouri, Columbia, Missouri 65211 Received 26 March 1991/Accepted 20 June 1991 We characterized fiveisolatesofAgrobacteriumtumefaciensfrom naturallyoccurringgallson Chrysanthe- m u m morifolium.Theisolatesare similar,possiblyidentical,members ofa singlestrainofA. tumefaciensthat w e designate Chry5. The strain isa biotype I, as indicated by its response to both newly described and traditionalbiotypetests.Chry5produces tumorson atleast10plantspecies.Itisunusual initsabilitytoform efficientlylarge tumors on soybean (Glycinemax), a speciesnormallyrefractorytotransformation. Chry5 is unabletoutilizeoctopineor mannopineas a carbonsource. AlthoughChry5can catabolizea singleisomereach of nopaline and succinamopine, itdiffers from other known nopaline and succinamopine strains in its insensitivitytoagrocin84.Thispatternofopinecatabolismisunique among Agrobacteriumstrainsexamined todate.AllfiveisolatesofChry5 contain atleasttwo plasmids, one ofwhich shares homology with pTiB6. Crown gall,adisease thataffectsawide varietyofplant species(11),iscausedby thebacterialpathogenAgrobacte- rium tumefaciens. The disease attracts considerable atten- tionbecause oftheabilityofthecausalorganismtoactasa natural genetic engineer. A piece of bacterial DNA, the T-DNA, istransferredintoaplantcell,whereitisintegrated intothe genome and expressed, giving risetothe gall(see references36and 43 forreviews). Strains of A. tumefaciens are diverse and have been classifiedinseveralways. Three biotypes have been recog- nized(18,29)onthebasisofpatternofresponsestoavariety of biochemical and physiological tests. A. tumefaciens strainsalsocanbe subdivided accordingtotheirabilitiesto catabolize opines or to produce them in tumors (13, 32); thesecharacteristicsarespecifiedby theTiplasmid (5,24). Althoughearlywork dealtonlywithoctopineand nopaline, increasingnumbers oftumor-specific compounds arebeing described (33). Alternatively, strains have been categorized by various aspectsofhostrange.Forexample,anA.tumefaciensstrain canbedescribedashavingwideorlimitedhostrangeonthe basisofthenumber ofsusceptibleplantspecies.Hostrange appears to be an isolate-specific characteristic, since dif- ferent isolates from a single tumor can show distinctive patterns of specificity (1). The ability ofa strain to cause tumors on differentsubspecies, orcultivars,ofasinglehost alsomay vary.Thishasbeenobservedinavarietyofplants (for some examples, see reference 14and references there- in).Inallinstances, some degree ofspecificityisapparent, indicating that even closely related plants can differ in susceptibility. This cultivarspecificitycan be exploited for the purpose of efficient genetic engineering, breeding for...
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