The rolB Gene of Agrobacterium rhizogenes Does Not Increase the Auxin Sensitivity of Tobacco Protoplasts by Modifying the Intracellular Auxin Concentration

Delbarre, Alain; Muller, Philippe; Imhoff, V.; Barbier‐Brygoo, Hélène; Maurel, Christophe; Leblanc, Nathalie; Perrot‐Rechenmann, Catherine; Guern, J.

doi:10.1104/pp.105.2.563

Cited by 68 publications

(38 citation statements)

References 16 publications

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“…Protoplasts derived from such tobacco plants are 105-fold more sensitive to auxin than protoplasts of wild-type plants . However, neither free nor conjugated IAA levels were modified in P35S-rolB-transformed tobacco plants or protoplasts (Nilsson et al, 1993;Schmülling et al, 1993;Delbarre et al, 1994). It is therefore unlikely that the surl mutant is affected in its ability to sense auxin.…”

Section: Linkage Analysismentioning

confidence: 94%

Superroot, a recessive mutation in Arabidopsis, confers auxin overproduction.

et al. 1995

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We have isolated seven allelic recessive Arabidopsis mutants, designated superroot (surl-7 to surl-7), displaying several abnormalities reminiscent of auxin effects. These characteristics include small and epinastic cotyledons, an elongated hypocotyl in which the connection between the stele and cortical and epidermal cells disintegrates, the development of excess adventitious and lateral roots, a reduced number of leaves, and the absence of an inflorescence. When germinated in the dark, surl mutants did not develop the apical hook characteristic of etiolated seedlings. We were able to phenocopy the Surl-phenotype by supplying auxin to wild-type seedlings, to propagate surl explants on phytohormonedeficient medium, and to regenerate shoots from these explants by the addition of cytokinins alone to the culture medium. Analysis by gas chromatography coupled to mass spectrometry indicated increased levels of both free and conjugated indole-3-acetic acid. surl was crossed to the mutant axr2 and the altered-auxin response mutant ctrl. The phenotype of both double mutants was additive. The surl gene was mapped on chromosome 2 at 0.5 centimorgans from the gene encoding phytochrome B.

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Section: Linkage Analysismentioning

confidence: 94%

Superroot, a recessive mutation in Arabidopsis, confers auxin overproduction.

et al. 1995

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“…Subsequent analyses have demonstrated that, unlike the original hypothesis suggested, rolB activity does not interfere with the endogenous auxin metabolism (Delbarre et al, 1994;Nilsson et al, 1993a;SchmLilling et al, 1993a). In a recent publication Fillipini et al (1996) reported that the rolB enzyme also has an in vitro tyrosine phosphatase activity.…”

Section: Introductionmentioning

confidence: 99%

Chemically induced expression of the rolC‐encoded β‐glucosidase in transgenic tobacco plants and analysis of cytokinin metabolism: rolC does not hydrolyze endogenous cytokinin glucosides in planta

et al. 1996

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SummaryThe rolC gene of Agrobacterium rhizogenes T-DNA plays an essential role in the establishment of hairy root disease and its overexpression in transgenic plants causes pleiotropic developmental alterations. This study investigated whether the biological activity of the rolC 13-glucosidase is due to an alteration of the cytokinin balance in planta.HPLC radiocounting assays of [3H]-Iabeled cytokinin glucosides fed exogenously to tobacco leaf disks, to rolC expressing Escherichia coil cells or cell-free extracts showed that cytokinin N3-and O-glucosides are the preferred substrate of the rolC protein. Hydrolysis of N7-and N9-glucosides was not detected at substrate concentrations close to physiological levels. Furthermore, these conjugates were also not active as cytokinins in biotests when fed to rolC-expressing tissues. For analysis of the rolC activity on endogenous cytokinin conjugates the gene was expressed under the transcriptional control of a modified tetracycline-inducible 35S promoter. This was done to avoid possible interference with secondary effects or plant homeostatic mechanisms which could mask primary in planta events when transgenes are expressed constitutively. No changes in the endogenous pool of different cytokinin glucosides, as determined by a newly developed electrospray tandem mass spectroscopy directly coupled to high performance liquid chromatography, were found following chemical induction of the rolC gene. Also the levels of free cytokinins remained unchanged after gene induction. Hybrid tobacco plants expressing the cytokinin-

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“…This pattern resembled that of stem slices inoculated with A. rhizogenes. The results also correspond with the increased root formation on explants of kiwi transformed with ArolA+BrolB+CrolC [20]. It suggests that rolA and rolC enhanced the promotive effect of rolB on rooting.…”

Section: Discussionmentioning

confidence: 49%

The effects of exogenous auxin and rol genes on root formation in Rosa hybrida L. ‘Moneyway’

Salm¹,

Toorn²,

Cate³

et al. 1996

Plant Growth Regul

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The effect of indole-3-butyric acid (IBA) on the formation of non-transformed and rol gene transformed roots on stem slices of in vitro cultured shoots of Rosa hybridu L. 'Moneyway' was examined. Formation of adventitious roots on this rootstock was dependent on the IBA dose; it was not affected by the presence of other root primordia on the same explant. Application of 0.32 to 1 PM IBA during 5 days, followed by transfer to medium without hormones resulted in maximum root formation (90%) after three weeks. The formation of such untransformed roots was completely inhibited by transfer to medium with 5 mg 1-l kanamycin two days after excision. Ri roots were formed upon inoculation with A. rhizogenes LBA9402 harbouring two plasmids: pRil855, comprising the rol genes and the binary plasmid p 35Sgusintron with the nptll gene for kanamycin resistance and the CaMV 35Sgusintron gene. The formation of these Ri roots on kanamycin-containing medium was independent of the presence of IBA. Stem slices inoculated with a disarmed A. tumefuciens GV3 101, harbouring only the nptll gene, formed callus and subsequently roots in the presence of kanamycin exclusively on medium with high IBA concentrations (10 or 100 pw. Root formation at 100 PM IBA was considerably improved by transformation with the rolB gene under the influence of the strong CaMV 35s promoter. In addition, low IBA (0.1 and 1 ,uM) stimulated the formation of roots only on stem slices transformed with A. tumefuciens harbouring the rolA+rolB+rolC genes; the rooting response at 10 PM IBA was much improved. It was concluded that the 35SrolB gene and especially a combination of rolA, B and C genes promote the rooting response.Abbreviations: BAP = 6-benzylaminopurine; FeEDDHA = ferric ethylenediamine di(o-hydroxyphenylacetate); IBA = indole-3-butyric acid; LSD = least significant difference; RIM = root induction medium; SE = standard error; X-glut = 5-bromo-4-chloro-3-indolyl glucuronide

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The rolB Gene of Agrobacterium rhizogenes Does Not Increase the Auxin Sensitivity of Tobacco Protoplasts by Modifying the Intracellular Auxin Concentration

Cited by 68 publications

References 16 publications

Superroot, a recessive mutation in Arabidopsis, confers auxin overproduction.

Superroot, a recessive mutation in Arabidopsis, confers auxin overproduction.

Chemically induced expression of the rolC‐encoded β‐glucosidase in transgenic tobacco plants and analysis of cytokinin metabolism: rolC does not hydrolyze endogenous cytokinin glucosides in planta

The effects of exogenous auxin and rol genes on root formation in Rosa hybrida L. ‘Moneyway’

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