Molecular and genetic analysis of factors controlling host range in Agrobacterium tumefaciens

Yanofsky, Martin F.; Lowe, Brenda; Montoya, Alice L.; Rubin, Robert A.; Krul, William R.; Gordon, Milton P.; Nester, Eugene W.

doi:10.1007/bf00425665

Cited by 104 publications

(70 citation statements)

References 44 publications

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“…Strain A348 was chosen because it was incompatible with Steuben and because the incompatible interaction was associated with the induction of a necrotic reaction (29). The phenotypes of the parents and the distribution ofresistant and susceptible progeny are shown in Table VI.…”

Section: Screen Of F Progeny For Host-pathogen Interactionmentioning

confidence: 99%

“…We suggest that the effects of growth regulators on tumor frequency and hostpathogen specificity are independent of their mechanisms for modulating cell expansion. We know that host selectivity is modulated, in part, by the Ti-plasmid (1,17,29) and that LHR strains differ from WHR strains via a deletion in the promoter region of the LHR ipt locus (30) and by structural differences in the virC (30,31), virA loci (13), and the virA-virB junction (M Zapor, personal communication). We show here that host-pathogen specificity is also modulated by the host genome.…”

Section: Effect Of Morphological Correlates On the Necrotic Reactionmentioning

confidence: 99%

“…Expression of T-DNA in host cells alters the endogenous levels of auxin, cytokinin, and ethylene (6,11,17), which results in the loss of cellular totipotency (11,17 3,17,27). Bacterial host range and virulence determinants have been attributed to structural and organizational differences in T-DNA loci (1,17,21,(27)(28)(29)30) and to structural differences in at least two vir loci (30,31). Some investigators suggest that chromosomal loci might also modulate host selectivity (17,25).…”

Section: Introductionmentioning

confidence: 99%

“…The role of the host genome in Agrobacterium-host compatibility has not received as much consideration as that of the pathogen. However, intergeneric (3,12,25,26,29,30) and intraspecific and cultivar variations (1, 2, 7-9, 19, 23, 24, 27) in hostresponse to WHR and/or LHR strains have been reported. A preliminary analysis of Vitis hybrids showed that resistance to A. tumefaciens was a heritable trait (23).…”

Section: Introductionmentioning

confidence: 99%

“…Strains designated WHR2 infect more than 93 families of plants (3), while strains designated LHR infect only a few families, which include species of Vitis, Rubus, and a few of Nicotiana (1,3,17,27). Bacterial host range and virulence determinants have been attributed to structural and organizational differences in T-DNA loci (1,17,21,(27)(28)(29)30) and to structural differences in at least two vir loci (30,31). Some investigators suggest that chromosomal loci might also modulate host selectivity (17,25).…”

mentioning

confidence: 99%

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Physical, Chemical, Developmental, and Genetic Factors that Modulate the Agrobacterium-Vitis Interaction

Lowe¹,

Krul²

1991

Plant Physiol.

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Tumor formation in Vitis species and hybrids, incited by Agrobacterium tumefaciens, was altered by chemical, physical, developmental, and genetic variables. Knowledge of the effect of these variables was used to develop a stringent in vitro assay system to select parents for a study of genetic factors that modulate tumor formation. Tumor formation was reduced by short day preconditioning of assay plants and by inoculation of the morphological apex of isolated stem segments. Pretreatment of plants with auxin or cytokinin altered specificity in various combinations of strains and host genotypes. All Vitis species and hybrids formed tumors in response to strains designated as limited host range, but some displayed a necrotic reaction (cell death at and below site of inoculation) or a null response (same as the response to inoculation with an avirulent strain) to strains designated as wide host range (VC Knauf, CG Panagopoulos, EW Nester [1982] Phytopathology 72: 1545-1549). Screens of F1 progeny, derived from crosses of null, necrotic, and tumor-producing phenotypes, demonstrated that the null and the necrotic phenotypes were modulated by dominant and recessive host genes. The extent of cellular necrosis in the necrotic phenotype was modified by the morphological location of the inoculation site, by the presence of buds on the host stem, and by deletion of the tryptophane monooxygenase locus gene of the Ti-plasmid.The tumor-inducing plasmid ofAgrobacterium tumefaciens contains two regions, termed the virulence (vir) and tumorinducing DNA (T-DNA), that coordinately participate in the excision of DNA from the pathogen and its transfer into the host genome (11,17). The current model for infection of host cells by Agrobacterium predicts that phenolic metabolites produced by wounded plant cells activate plasmid vir genes of the bacterium (22). Once activated, the genes modulate the excision and packaging of T-DNA and facilitate its transfer into the host plant genome (17,22). Expression of T-DNA in host cells alters the endogenous levels of auxin, cytokinin, and ethylene (6,11,17), which results in the loss of cellular totipotency (11,17 3,17,27). Bacterial host range and virulence determinants have been attributed to structural and organizational differences in T-DNA loci (1,17,21,(27)(28)(29)30) and to structural differences in at least two vir loci (30,31). Some investigators suggest that chromosomal loci might also modulate host selectivity (17,25). The role of the host genome in Agrobacterium-host compatibility has not received as much consideration as that of the pathogen. However, intergeneric (3,12,25,26,29,30) and intraspecific and cultivar variations (1, 2, 7-9, 19, 23, 24, 27) in hostresponse to WHR and/or LHR strains have been reported. A preliminary analysis of Vitis hybrids showed that resistance to A. tumefaciens was a heritable trait (23).The primary goal of our research was to develop a system to study the interactions of bacterial virulence genes and host genes so that the molecular and bioch...

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Section: Screen Of F Progeny For Host-pathogen Interactionmentioning

confidence: 99%

Section: Effect Of Morphological Correlates On the Necrotic Reactionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

mentioning

confidence: 99%

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Physical, Chemical, Developmental, and Genetic Factors that Modulate the Agrobacterium-Vitis Interaction

Lowe¹,

Krul²

1991

Plant Physiol.

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The genetic and transcriptional organization of the vir region of the A6 Ti plasmid of Agrobacterium tumefaciens.

Stachel¹,

Nester²

1986

The EMBO Journal

416

391

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The genetic transformation of plant cells by Agrobacterium tumefaciens is mediated by the genes of the Ti plasmid vir region. To determine the genetic and transcriptional organization of the vir region of pTiA6, vir plasmid clones were saturated with insertion mutations of a Tn3‐lacZ transposon. This element is both an insertion mutagen and a reporter for the expression of the sequences into which it has inserted. One hundred and twenty‐four vir::Tn3‐lac insertions were analyzed for their mutagenic effect on Agrobacterium virulence, and for their expression of beta‐galactosidase activity, the lacZ gene product, in vegetative bacteria and in bacteria cocultivated with plant cells. These data in conjunction with genetic complementation results show that the pTiA6 vir region contains six distinct vir complementation groups: virA, virB, virC, virD, virE and virG. Mutations in these loci eliminate (virA, virB, virD and virG) or significantly restrict (virC and virE) the ability of Agrobacterium to transform plant cells. Each of the vir loci corresponds to a single vir transcription unit: virA is constitutively expressed and non‐inducible; virB, virC, virD and virE are expressed only upon activation by plant cells; and virG is both constitutively expressed and plant‐inducible. The two largest vir operons, virB and virD, are probably polycistronic. The pTiA6 vir region also contains plant‐inducible loci (pin) which are non‐essential for virulence.

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Virulence and supervirulence ofAgrobacterium tumefaciensin woody fruit plants

Cervera

López

Navarro

et al. 1998

Physiological and Molecular Plant Pathology

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Molecular and genetic analysis of factors controlling host range in Agrobacterium tumefaciens

Cited by 104 publications

References 44 publications

Physical, Chemical, Developmental, and Genetic Factors that Modulate the Agrobacterium-Vitis Interaction

Physical, Chemical, Developmental, and Genetic Factors that Modulate the Agrobacterium-Vitis Interaction

The genetic and transcriptional organization of the vir region of the A6 Ti plasmid of Agrobacterium tumefaciens.

Virulence and supervirulence ofAgrobacterium tumefaciensin woody fruit plants

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