Promoter tagging with a promoterless <i>ipt</i> gene leads to cytokinin‐induced phenotypic variability in transgenic tobacco plants: implications of gene dosage effects

Hewelt, Andreas; Prinsen, Els; Schell, Jeff; Onckelen, Harry Van; Schmülling, Thomas

doi:10.1046/j.1365-313x.1994.6060879.x

Cited by 107 publications

(79 citation statements)

References 36 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…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

134

View full text Add to dashboard Cite

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.

show abstract

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

134

View full text Add to dashboard Cite

show abstract

“…threshold also caused stunted plant growth, abnormal tissue development, and sensitivity but not tolerance to drought (Li et al, 1992;Hewelt et al, 1994;Wang et al, 1997;Synkova et al, 1999;Havlová et al, 2008). Therefore, appropriate manipulation of CK levels is necessary to increase leaf longevity and photosynthetic capacity under drought stress, taking into account the dosage effect of CKs on plant growth and stress responses.…”

Section: Discussionmentioning

confidence: 99%

Analysis of Cytokinin Mutants and Regulation of Cytokinin Metabolic Genes Reveals Important Regulatory Roles of Cytokinins in Drought, Salt and Abscisic Acid Responses, and Abscisic Acid Biosynthesis

et al. 2011

View full text Add to dashboard Cite

Cytokinins (CKs) regulate plant growth and development via a complex network of CK signaling. Here, we perform functional analyses with CK-deficient plants to provide direct evidence that CKs negatively regulate salt and drought stress signaling. All CK-deficient plants with reduced levels of various CKs exhibited a strong stress-tolerant phenotype that was associated with increased cell membrane integrity and abscisic acid (ABA) hypersensitivity rather than stomatal density and ABA-mediated stomatal closure. Expression of the Arabidopsis thaliana ISOPENTENYL-TRANSFERASE genes involved in the biosynthesis of bioactive CKs and the majority of the Arabidopsis CYTOKININ OXIDASES/DEHYDROGENASES genes was repressed by stress and ABA treatments, leading to a decrease in biologically active CK contents. These results demonstrate a novel mechanism for survival under abiotic stress conditions via the homeostatic regulation of steady state CK levels. Additionally, under normal conditions, although CK deficiency increased the sensitivity of plants to exogenous ABA, it caused a downregulation of key ABA biosynthetic genes, leading to a significant reduction in endogenous ABA levels in CK-deficient plants relative to the wild type. Taken together, this study provides direct evidence that mutual regulation mechanisms exist between the CK and ABA metabolism and signals underlying different processes regulating plant adaptation to stressors as well as plant growth and development.

show abstract

“…Progress in plant molecular genetics offered transformation with bacterial ipt as a tool for manipulation of endogenous CK levels. Several works described how the expression of ipt under the control of specific promoters leads to massively increased CK concentrations causing the so-called general CK syndrome, which comprises reduced apical dominance followed by release of axillary buds, reduced stem and leaf area, reduced root growth and retarded leaf senescence (Medford et al 1989;Schmülling et al 1989;Beinsberger et al 1991;Hewelt et al 1994;Zhang et al 1995;Gan and Amasino 1995;Redig et al 1996;Faiss et al 1997). Anther-specific expression of ipt in tobacco pointed to the effect of CKs on floral organ systems and reproductivity as well (Sa et al 2002).…”

Section: Transgenic Plants With Altered Ck Status As Tools For Undersmentioning

confidence: 99%

Cytokinins - recent news and views of evolutionally old molecules

Spíchal¹

2012

Functional Plant Biol.

154

169

View full text Add to dashboard Cite

Cytokinins (CKs) are evolutionally old and highly conserved low-mass molecules that have been identified in almost all known organisms. In plants, they evolved into an important group of plant hormones controlling many physiological and developmental processes throughout the whole lifespan of the plant. CKs and their functions are, however, not unique to plants. In this review, the strategies and mechanisms of plants – and phylogenetically distinct plant-interacting organisms such as bacteria, fungi, nematodes and insects employing CKs or regulation of CK status in plants – are described and put into their evolutionary context. The major breakthroughs made in the last decade in the fields of CK biosynthesis, degradation and signalling are also summarised.

show abstract

Promoter tagging with a promoterless ipt gene leads to cytokinin‐induced phenotypic variability in transgenic tobacco plants: implications of gene dosage effects

Cited by 107 publications

References 36 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.)

Analysis of Cytokinin Mutants and Regulation of Cytokinin Metabolic Genes Reveals Important Regulatory Roles of Cytokinins in Drought, Salt and Abscisic Acid Responses, and Abscisic Acid Biosynthesis

Cytokinins - recent news and views of evolutionally old molecules

Contact Info

Product

Resources

About