Transgenic Tobacco Plants Coexpressing the <i>Agrobacterium tumefaciens iaaM</i> and <i>iaaH</i> Genes Display Altered Growth and Indoleacetic Acid Metabolism

Sitbon, Folke; Hennion, S.; Sundberg, Björn; Little, C. H. A.; Olsson, Olof; Sandberg, Göran

doi:10.1104/pp.99.3.1062

Cited by 133 publications

(102 citation statements)

References 30 publications

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“…Classical tissue culture experiments have demonstrated that exogenous application of a low ratio of auxin to cytokinin promotes shoot regeneration from tobacco callus, while a high auxin to cytokinin ratio stimulates root formation (Skoog and Miller 1957). These observations are supported and extended by numerous studies in which heterologous expression of bacterial cytokinin-(isopentenyltransferase; ipt) and auxin biosynthesis enzymes (tryptophan monooxygenease, iaaM; indoleacetamide hydrolase; iaaH) has been used to alter endogenous levels of these hormones (Smigocki and Owens 1988;Sitbon et al 1992;Hewelt et al 1994;Eklöf et al 2000). BBM over-expression transgenics show elements of both cytokinin and auxin over-production phenotypes including ectopic shoot production and leaf wrinkling (cytokinin) and ectopic root production (auxin).…”

Section: Discussionmentioning

confidence: 73%

Heterologous expression of the BABY BOOM AP2/ERF transcription factor enhances the regeneration capacity of tobacco (Nicotiana tabacum L.)

Srinivasan

Liu

Heidmann

et al. 2006

Planta

142

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Gain-of-function studies have shown that ectopic expression of the BABY BOOM (BBM) AP2/ ERF domain transcription factor is suYcient to induce spontaneous somatic embryogenesis in Arabidopsis (Arabidopsis thaliana (L.) Heynh) and Brassica napus (B. napus L.) seedlings. Here we examined the eVect of ectopic BBM expression on the development and regenerative capacity of tobacco (Nicotiana tabacum L.) through heterologous expression of Arabidopsis and B. napus BBM genes. 35S::BBM tobacco lines exhibited a number of the phenotypes previously observed in 35S::BBM Arabidopsis and B. napus transgenics, including callus formation, leaf rumpling, and sterility, but they did not undergo spontaneous somatic embryogenesis. 35S::BBM plants with severe ectopic expression phenotypes could not be assessed for enhanced regeneration at the seedling stage due to complete male and female sterility of the primary transformants, therefore fertile BBM ectopic expression lines with strong misexpression phenotypes were generated by expressing a steroid-inducible, posttranslationally controlled BBM fusion protein (BBM:GR) under the control of a 35S promoter. These lines exhibited spontaneous shoot and root formation, while somatic embryogenesis could be induced from in-vitro germinated seedling hypocotyls cultured on media supplemented with cytokinin. Together these results suggest that ectopic BBM expression in transgenic tobacco also activates cell proliferation pathways, but diVerences exist between Arabidopsis/B. napus and N. tabacum with respect to their competence to respond to the BBM signalling molecule.

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Section: Discussionmentioning

confidence: 73%

Heterologous expression of the BABY BOOM AP2/ERF transcription factor enhances the regeneration capacity of tobacco (Nicotiana tabacum L.)

Srinivasan

Liu

Heidmann

et al. 2006

Planta

142

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“…The development of molecular biology and gene transfer technology has made it possible to study the physiological effects of elevated endogenous auxin levels. The expression of bacterial auxin biosynthesis genes in plants results in the overproduction of both free and conjugated IAA forms (Klee et al, 1987;Romano et al, 1993;Sitbon et al, 1991Sitbon et al, , 1992Sitbon et al, , 1993. Alternatively, in transgenic tobacco plants producing an IAA-lysine synthetase, an increase in auxin conjugates was observed which was not always correlated with a comparable decrease in the level of free IAA (Romano et al, 1991;Spena et al, 1991).…”

Section: Introductionmentioning

confidence: 99%

Sur2 mutations of Arabidopsis thaliana define a new locus involved in the control of auxin homeostasis

et al. 1998

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SummaryA new auxin homeostasis gene in Arabidopsis called SUR2 has been identified. This gene, mapped to the bottom of chromosome 4, is defined by two recessive nuclear mutants designated superroot2 (sur2), which display several abnormalities reminiscent of auxin effects. A number of these characteristics are similar to the phenotype of the previously described auxin-overproducing mutant superroot1 (sur1); however, several lines of evidences reveal that the SUR2 gene defines a new key point in the regulation of endogenous auxin concentrations. The phenotype of the sur1 sur2 double mutant is additive. Analysis by gas chromatography coupled to mass spectrometry indicated increased levels of free indole-3-acetic acid correlated with a decreased level of bound auxin in the sur2 mutant. These results suggest that SUR2 may be involved in the control of auxin conjugation.

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“…Quantitative analysis of ABA, IAA, and IAA conjugates (liberated after hydrolysis for 1 h at 100°C in 7 M NaOH) was performed by GC-SIM-MS using [l3C6]IAA and ['H,]ABA as intemal standards. The method for purification and quantitative analysis by GC-MS has been described by Sundberg (1990) and Sitbon et al (1992a).…”

Section: Quantification Of Iaa and Abamentioning

confidence: 99%

“…Subsequently, such activities have to be correlated to alterations in the hormone pools of transgenic plants expressing these activities. Thus, in iaaH/iaaM-expressing plants, which are stunted dwarfs with a strong apical dominance and excessive adventitious root formation, a correlation to increased pools of free IAA and IAA conjugates was demonstrated (Klee et al, 1987;Sitbon et al, 1992aSitbon et al, , 1992b. Plants expressing iaaL showed, as a result of increasing the cytokinin-to-IAA ratio, cytokinin-like effects, with reduced apical dominance and reduced root growth, which were correlated to reduced levels of free IAA and increased levels of IAA conjugates (Romano et al, 1991;Spena et al, 1991).…”

mentioning

confidence: 99%

Hormonal Characterization of Transgenic Tobacco Plants Expressing the rolC Gene of Agrobacterium rhizogenes TL-DNA

et al. 1993

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Transgenic Tobacco Plants Coexpressing the Agrobacterium tumefaciens iaaM and iaaH Genes Display Altered Growth and Indoleacetic Acid Metabolism

Cited by 133 publications

References 30 publications

Heterologous expression of the BABY BOOM AP2/ERF transcription factor enhances the regeneration capacity of tobacco (Nicotiana tabacum L.)

Heterologous expression of the BABY BOOM AP2/ERF transcription factor enhances the regeneration capacity of tobacco (Nicotiana tabacum L.)

Sur2 mutations of Arabidopsis thaliana define a new locus involved in the control of auxin homeostasis

Hormonal Characterization of Transgenic Tobacco Plants Expressing the rolC Gene of Agrobacterium rhizogenes TL-DNA

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