Expression of the isopentenyl transferase gene is regulated by auxin in transgenic tobacco tissues

Zhang, X. D.; Letham, D. S.; Zhang, R.; Higgins, T. J. V.

doi:10.1007/bf01979922

Cited by 21 publications

(6 citation statements)

References 46 publications

(54 reference statements)

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“…Regenerated shoots at first did not form roots and were devoid of apical domination, a fact that was also reported by others [46][47][48]. As reported by Zhang and co-workers, [49], the expression of isopentyl transferase in transgenic tobacco plants may be controlled by auxins. We have therefore used exogenous auxin and this allowed us to obtain normal transgenic plants having an intermediate level of cytokinine in comparison with normal transgenic plants and the crown gall tissue [50].…”

Section: An Experimental Model For Studying the Role Of Isopentyl Trasupporting

confidence: 64%

Transgenic Plants Expressing Bacterial Genes as a Model System for Plant Functional Genomics

Пирузян¹,

Goldenkova-Pavlova²,

Abdeev³

et al. 2006

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The functional analysis of plant genes employs various comprehensive approaches that include transcriptome analysis using microchips, gene knockout, RNA interference, and various experimental models. We have proposed a novel experimental model approach for plant functional genomics. It is based on creating and studying transgenic plants that express bacterial genes which are functionally similar to plant genes. The validity of this approach owes to the similarity of basic pro-and eukaryotic metabolic pathways and gene networks controlling the functioning of these organisms under normal conditions and in response to abiotic and biotic stresses.Our studies using molecular biology, physiology and biochemistry methods have demonstrated adequateness of the proposed strategy. It allows the modeling of processes taking place in the plant cell and differential assessment of contribution of individual enzymes. Our results indicate that the proposed approach is highly effective for functional genomics, namely, for determining the function of a gene product in vivo. The experimental data can be further used as a basis for elaboration of gene networks controlling particular physiological processes and stress responses of plants to biotic and abiotic environmental factors.

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Section: An Experimental Model For Studying the Role Of Isopentyl Trasupporting

confidence: 64%

Transgenic Plants Expressing Bacterial Genes as a Model System for Plant Functional Genomics

Пирузян¹,

Goldenkova-Pavlova²,

Abdeev³

et al. 2006

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“…The phenotypes of Mt CRE1 RNAi roots are consistent with a general role for cytokinins in the control of the initiation of lateral root organs and more generally on the control of root architecture in response to environmental conditions and root apical dominance (Franco-Zorrilla et al, 2002;Aloni et al, 2006). It is well known that a primary target of cytokinin action is cell cycle control (Redig et al, 1996;Zhang et al, 1996). Our results from Mt CRE1-silenced roots could be integrated by proposing that reduced nodulation may rely on a block of cortical cell divisions, whereas increased lateral root formation may be related to an activation of pericycle divisions.…”

Section: Discussionmentioning

confidence: 56%

TheMedicago truncatulaCRE1 Cytokinin Receptor Regulates Lateral Root Development and Early Symbiotic Interaction withSinorhizobium meliloti

2006

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Legumes develop different types of lateral organs from their primary root, lateral roots and nodules, the latter depending on a symbiotic interaction with Sinorhizobium meliloti. Phytohormones have been shown to function in the control of these organogeneses. However, related signaling pathways have not been identified in legumes. We cloned and characterized the expression of Medicago truncatula genes encoding members of cytokinin signaling pathways. RNA interference of the cytokinin receptor homolog Cytokinin Response1 (Mt CRE1) led to cytokinin-insensitive roots, which showed an increased number of lateral roots and a strong reduction in nodulation. Both the progression of S. meliloti infection and nodule primordia formation were affected. We also identified two cytokinin signaling response regulator genes, Mt RR1 and Mt RR4, which are induced early during the symbiotic interaction. Induction of these genes by S. meliloti infection is altered in mutants affected in the Nod factor signaling pathway; conversely, cytokinin regulation of the early nodulin Nodule Inception1 (Mt NIN) depends on Mt CRE1. Hence, cytokinin signaling mediated by a single receptor, Mt CRE1, leads to an opposite control of symbiotic nodule and lateral root organogenesis. Mt NIN, Mt RR1, and Mt RR4 define a common pathway activated during early S. meliloti interaction, allowing crosstalk between plant cytokinins and bacterial Nod factors signals.

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“…Our previous study using cytokinin-overproducing tobacco plants revealed a strong increase in CKX activity as a consequence of elevated cytokinin levels (Motyka et al 1996;Motyka et al 2003). Stimulation of CKX activity by endogenous or externally applied (both substrate and non-substrate) cytokinins has also been reported in other plants and plant cultures (Chatfield and Armstrong 1986;Kamı´nek and Armstrong 1990;Motyka and Kamı´nek 1990;Zhang et al 1996;Auer et al 1999). It is evident that BA, which is intensively glucosylated (data not shown), is capable of stimulating both metabolic processes, i.e., N-glucosylation and oxidative breakdown.…”

Section: The Effect Of Exogenous Cytokinins On Cytokinin 7n-glucosylamentioning

confidence: 86%

Effect of exogenous cytokinins, auxins and adenine on cytokinin N-glucosylation and cytokinin oxidase/dehydrogenase activity in de-rooted radish seedlings

Blagoeva

Dobrev

Malbeck

et al. 2004

Plant Growth Regulation

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The role of cytokinin N-glucosylation and degradation by cytokinin oxidase/dehydrogenase (CKX, EC 1.5.99.12) in response to application of exogenous auxins (2,4-dichlorophenoxyacetic acid [2,4-D] and a-naphthaleneacetic acid [NAA]) and cytokinins (N 6 -benzyladenine [BA] and trans-zeatin [Z]) was investigated in de-rooted seedlings of Raphanus sativus L. cv. Rampouch. Both auxins applied for 24 h at 1 and 10 lM concentration increased N-glucosylation of exogenously applied [ 3 H]dihydrozeatin (DHZ) by up to 20%. The level of endogenous 7N-glucosides (of Z, isopentenyladenine [iP] and DHZ) was increased by 2,4-D and NAA at 10 lM concentration by 28 and 23%, respectively, the level of Z being decreased by 90 and 59%, respectively. 2,4-D and NAA suppressed CKX activity ca. by half. Exogenous cytokinins Z and BA applied at 1 and 10 lM concentration stimulated 7N-glucosylation of [ 3 H]DHZ (by up to 40%). BA both at 1 and 10 lM, increased the level of endogenous Z by up to 35% and that of 7N-glucosides by up to 27%. BA application also strongly stimulated CKX activity (by up to 180%). Feeding with 1 and 10 lM Z resulted in ca. 100-fold and 2000-fold increase of Z level, respectively. The main metabolite, Z7G, was increased ca. 6-fold and 60-fold, respectively. Levels of Z 9-glucoside (Z9G), trans-zeatin riboside (ZR) and Z O-glucoside (ZOG) were elevated to lesser extent. As compared to BA, Z had only negligible effect on CKX activity. Adenine (1-500 lM) was preferentially 7N-glucosylated inhibiting competitively 7N-glucosylation of [ 3 H]DHZ. At high concentrations (100-500 lM) it increased endogenous levels of active cytokinins, especially of Z, however, it had no effect on CKX activity. Cytokinin N-glucosylation proved to be involved in down-regulation of active cytokinins in response to auxin and in the re-establishment of cytokinin homeostasis following application of exogenous cytokinins.

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Expression of the isopentenyl transferase gene is regulated by auxin in transgenic tobacco tissues

Cited by 21 publications

References 46 publications

Transgenic Plants Expressing Bacterial Genes as a Model System for Plant Functional Genomics

Transgenic Plants Expressing Bacterial Genes as a Model System for Plant Functional Genomics

TheMedicago truncatulaCRE1 Cytokinin Receptor Regulates Lateral Root Development and Early Symbiotic Interaction withSinorhizobium meliloti

Effect of exogenous cytokinins, auxins and adenine on cytokinin N-glucosylation and cytokinin oxidase/dehydrogenase activity in de-rooted radish seedlings

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