Controlled Cytokinin Production in Transgenic Tobacco Using a Copper-Inducible Promoter

McKenzie, Marian J.; Mett, Vadim; Reynolds, Paul H. S.; Jameson, Paula E.

doi:10.1104/pp.116.3.969

Cited by 125 publications

(71 citation statements)

References 42 publications

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“…The use of a heavy metal-inducible promoter to control the target gene expression could avoid potential harmful effects due to overexpression of the target gene under control of constitutive promoters in transgenic plants. For example, the yeast copper-inducible promoter system has been well characterized in transgenic tobacco plants for controlling GUS (Mett et al, 1993) and cytokinin synthase (ipt) genes (McKenzie et al, 1998). Several promoters have failed to induce gene expression in response to cadmium in transgenic plants.…”

Section: The Pvsr2 Promoter May Be Useful In Transgenic Plant Studiesmentioning

confidence: 99%

Characterization of a Novel Plant Promoter Specifically Induced by Heavy Metal and Identification of the Promoter Regions Conferring Heavy Metal Responsiveness

Zhang

Chai

2006

Plant Physiology

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The bean (Phaseolus vulgaris) stress-related gene number 2 (PvSR2) gene responds to heavy metals but not to other forms of environmental stresses. To elucidate its heavy metal-regulatory mechanism at the transcriptional level, we isolated and characterized the promoter region (21623/148) of PvSR2. Deletions from the 5# end revealed that a sequence between 2222 and 2147 relative to the transcriptional start site was sufficient for heavy metal-specific induction of the promoter region of PvSR2. Detailed analysis of this 76-bp fragment indicated that heavy metal-responsive elements were localized in two regions (2222/2188 and 2187/2147), each of which could separately confer heavy metal-responsive expression on the b-glucuronidase gene in the context of a minimal cauliflower mosaic virus 35S promoter. Region I (2222/2188) contains a motif (metalregulatory element-like sequence) similar to the consensus metal-regulatory element of the animal metallothionein gene, and mutation of this motif eliminated the heavy metal-inducible function of region I. Region II (2187/2147) had no similarity to previously identified cis-acting elements involved in heavy metal induction, suggesting the presence of a novel heavy metalresponsive element. Transformed tobacco (Nicotiana tabacum) seedlings expressing b-glucuronidase under control of the PvSR2 promoter region (2687/148) showed heavy metal-specific responsive activity that depended on the type and concentration of the heavy metal and the type of organ. These findings further our understanding of the regulation of PvSR2 expression and provide a new heavy-metal-inducible promoter system in transgenic plants.In plants, a number of heavy metals are essential for normal growth as cofactors and as structural and catalytic components of proteins and enzymes. These micronutrients, as well as nonessential heavy metals such as cadmium, are toxic at high levels. Plants have evolved a suite of mechanisms that control and respond to the uptake and accumulation of both essential and nonessential heavy metals. These mechanisms include the chelation and sequestration of heavy metals by particular ligands including small peptides, organic acids, and amino acids, which bind free metal ions. They contribute to metal detoxification by buffering cytosolic metal ions (Clemens, 2001). The two best-characterized heavy metal-binding ligands in plant cells are the phytochelatins (PCs) and metallothioneins (MTs; for review, see Cobbett and Goldsborough, 2002). MTs are Cys-rich polypeptides encoded by a family of genes. In contrast, PCs are a family of enzymatically synthesized Cys-rich peptides. The induction of PC synthesis is based on the posttranscriptional activation of preformed PC synthase and is not under transcriptional control.Several heavy metal-inducible genes have been reported in plants (Hagen et al., 1988;Lescure et al., 1991;Berna and Bernier, 1999), but surprisingly, little is known about the transcriptional regulation of gene expression in response to heavy metals. In particular, the cis-...

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Section: The Pvsr2 Promoter May Be Useful In Transgenic Plant Studiesmentioning

confidence: 99%

Characterization of a Novel Plant Promoter Specifically Induced by Heavy Metal and Identification of the Promoter Regions Conferring Heavy Metal Responsiveness

Zhang

Chai

2006

Plant Physiology

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“…This gene has been widely employed in stay-green engineering studies with varied results. Ipt expression under the control of a constitutive promoter (Li et al, 1992), heat shock promoter Phsp70 (Smigocki, 1991;Van Loven et al, 1993), or copper-induced promoter (McKenzie et al, 1998) resulted in abnormal phenotypes. Gan and Amasino (1995) generated an autoregulatory cycle for ipt expression using a senescence-specific promoter, P SAG12 , from Arabidopsis (Arabidopsis thaliana).…”

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confidence: 99%

Identification and Application of a Rice Senescence-Associated Promoter

et al. 2010

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SAG39 is a rice (Oryza sativa) gene that encodes a cysteine protease. SAG39 shares 55% homology with the Arabidopsis (Arabidopsis thaliana) senescence-associated protein SAG12. The promoter for SAG39 (P SAG39 ) was isolated, and SAG39 expression was determined to be relatively low in mature leaves, while not expressed in the endosperm. SAG39 mRNA levels increased as senescence progressed, with maximum accumulation of transcripts at late senescence stages. Gel retardation assays indicated that two cis-acting elements in P SAG39 , HBOXCONSENSUSPVCHS and WRKY71OS, responded to leaf senescence. To test if P SAG39 could be useful for increasing rice yields by increasing cytokinin content and delaying senescence, homozygous transgenic plants were obtained by linking P SAG39 to the ipt gene and introducing it into Zhonghua 11. The chlorophyll level of the flag leaf was used to monitor senescence, confirming the stay-green phenotype in P SAG39 :ipt transgenic rice versus wild-type plants. Changes in the cytokinin content led to early flowering and a greater number of emerged panicles 70 d after germination in the transgenic rice. Measurements of sugar and nitrogen contents in flag leaves demonstrated a transition in the source-sink relationship in transgenic plants triggered at the onset of leaf senescence, with the nitrogen content decreasing more slowly, while sugars were removed more rapidly than in wild-type plants. The importance of these changes to rice physiology, yield, and early maturation will be discussed.

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“…Such abnormalities occur in condition where constitutive promoters like the cauliflower mosaic virus promoter CaMV35S or the ubiquitin maize promoter is used to drive the gene to the extent of preventing studies on cytokinin overproduction in normal plant tissues (McKenzie et al, 1998). In maize, the ipt gene has been expressed using senescence-activated promoters (Young et al, 2004;Robson et al, 2004).…”

Section: Introductionmentioning

confidence: 99%

Drought tolerant tropical maize (Zea mays L.) developed through genetic transformation with isopentenyltransferase gene

Bedada¹,

Seth²,

Runo³

et al. 2016

Afr. J. Biotechnol.

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Maize is a staple food crop for millions of Africans. Despite this fact, African farmers have been harvesting average grain yield of not more than 2 t/ha while there is a potential of producing more than 10 t/ha. Drought is one of the major abiotic constraints contributing to this low productivity. Drought diminishes crop productivity mainly by causing premature leaf senescence. The ipt gene codes for isopentenyltransferase (IPT) enzyme which catalyzes the rate limiting step in the biosynthesis of cytokinin and has been shown to enhance tolerance to drought in transgenic crops by delaying drought-induced leaf senescence. This created interest to investigate if ipt gene can be useful in enhancing drought tolerance in locally adapted African tropical maize genotypes. The tropical maize inbred line CML216 was transformed with ipt gene using Agrobacterium-mediated transformation method. Five transgenic lines which were proved to be stably transformed through Southern blot analysis with copy number of 2 to 4 per event were developed. In drought assay carried out in the glass house, transgenic lines expressing the ipt gene showed tolerance to drought as revealed by delayed leaf senescence compared to the wild type plants. Transgenic plants maintained higher relative water content and total chlorophyll during the drought period and produced significantly higher mean grain yield of 44.3 g/plant while the wild type plants produced mean grain yield of 1.43 g/plant. It is proposed that the transgenic lines developed in this study can be further tested for tolerance to drought under contained field trials. Furthermore, transgenic lines developed can be used in breeding programs to improve drought tolerance in other commercial tropical maize genotypes through conventional breeding.

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Controlled Cytokinin Production in Transgenic Tobacco Using a Copper-Inducible Promoter

Cited by 125 publications

References 42 publications

Characterization of a Novel Plant Promoter Specifically Induced by Heavy Metal and Identification of the Promoter Regions Conferring Heavy Metal Responsiveness

Characterization of a Novel Plant Promoter Specifically Induced by Heavy Metal and Identification of the Promoter Regions Conferring Heavy Metal Responsiveness

Identification and Application of a Rice Senescence-Associated Promoter

Drought tolerant tropical maize (Zea mays L.) developed through genetic transformation with isopentenyltransferase gene

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