Disease relevance of ipt

• Overexpression of the isopentenyltransferase gene (ipt) from the Ti-plasmid of Agrobacterium tumefaciens increases cytokinin levels, leading to generation of shoots from transformed plant cells [1].

High impact information on ipt

• When combined with a dexamethasone-inducible system for controlling expression, ipt expression can be used to select for transgenic regenerants without using an antibiotic-resistance marker [1].
• Specifically, the iaaM and ipt oncogenes, which show approximately 90% DNA sequence identity across studied A. tumefaciens strains, are required for tumor formation [2].
• By expressing two self-complementary RNA constructions designed to initiate RNA interference (RNAi) of iaaM and ipt, we generated transgenic Arabidopsis thaliana and Lycopersicon esculentum plants that are highly resistant to crown gall disease development [2].
• We found that the transcriptional regulator Ros controls expression of the plant oncogene ipt, which encodes isopentenyl transferase, in A. tumefaciens [3].
• Agrobacterium transcriptional regulator Ros is a prokaryotic zinc finger protein that regulates the plant oncogene ipt [3].

Chemical compound and disease context of ipt

• In contrast to the ipt gene from Agrobacterium, which primarily increases zeatin levels, Sho expression in petunia and tobacco especially enhances the levels of certain N6-(delta2-isopentenyl) adenosine (2iP) derivatives [4].
• Sequence of the iaa and ipt region of different Agrobacterium tumefaciens biotype III octopine strains: reconstruction of octopine Ti plasmid evolution [5].
• Thus a cell culture system of tobacco transformed with the ipt gene from Agrobacterium tumefaciens for cytokinin production and which when manipulated with auxin and sucrose leads to induction of xylogenesis, has been used as a source for purification of the enzyme [6].

Biological context of ipt

• An ipt promoter::cat reporter gene fusion showed a 10-fold increase in ipt promoter activity in A. tumefaciens ros mutant strains when compared with wild type [3].
• Cytokinins are a class of phytohormones that play a critical role in plant growth and development. sob5-D, an activation-tagging mutant, shows phenotypes typical of transgenic plants expressing the Agrobacterium tumefaciens isopentenyltransferase (ipt) gene that encodes the enzyme catalyzing the first step of cytokinin biosynthesis [7].
• Although PTGS has proven effective against a variety of target genes, we found that a much higher percentage of transgenic lines silenced iaaM than ipt, suggesting that transgene sequences influenced the effectiveness of PTGS [8].
• Promoter tagging with a promoterless ipt gene leads to cytokinin-induced phenotypic variability in transgenic tobacco plants:implications of gene dosage effects [9].
• Expression of ipt, a cytokinin biosynthetic gene from Agrobacterium tumefaciens, under the control of the promoter from a senescence-associated gene (SAG12) has been one approach used to delay senescence [10].

Associations of ipt with chemical compounds

• Tobacco plants have been transformed with a T-DNA construct harboring a promoterless cytokinin-synthesizing ipt gene close to the right T-DNA border [9].
• The WHR TA-region resembles the biotype I octopine region, whereas the LHR TA-region is a recent deletion derivative of the WHR TA-region, which lacks the iaa genes and part of the ipt gene [11].
• In high light (300 mumol PPFD m-2 s-1), ipt mRNA was detected and zeatin/zeatin glucoside levels were 10-fold higher than in control plants or when transformants were grown in low light (30 mumol PPFD m-2 s-1) [12].
• Although exogenous benzyladenine did not directly affect ipt gene expression, it did antagonize the effect of auxin on levels of cytokinins and IPT mRNA and protein [13].
• Also, increased levels (10- to 20-fold) of isopentenyl adenosine, the product of the reaction catalyzed by isopentenyl transferase, were detected in ros mutant strains [3].

Other interactions of ipt

• The virD2 and ipt primer pairs did not interfere with each other when included in the same PCR amplification, and this permitted simultaneous detection of both genes in a single reaction [14].
• To test whether increased endogenous cytokinin accumulation led to NaCl stress symptoms, the gene ipt from Agrobacterium tumefaciens, encoding isopentenyl transferase, was transformed into Nicotiana tabacum cv. SR-1 under the control of the light-inducible rbcS-3A promoter from pea [12].
• Sequence analysis of the 4.7 kb right part of this fragment allowed us to identify the pTi82.139 ipt, 6b and nos coding sequences. pTi82.139 lacks the 6a gene, which lies between the ipt and 6b genes in pTiC58 [15].
• To test its biological activity, the Tm-4 ipt gene was inserted into a specially constructed, disarmed Ti vector lacking tzs and tested on tobacco, where the rearranged ipt gene induced shoot formation [16].

Analytical, diagnostic and therapeutic context of ipt

• PCR primers corresponding to conserved sequences in ipt, the T-DNA-borne cytokinin synthesis gene, detected only Agrobacterium tumefaciens and distinguished it from Agrobacterium rhizogenes [14].
• The cytokinin gene, isopentenyl transferase (ipt), was placed under the control of a heat-inducible promoter from the Drosophila melanogaster hsp70 gene and introduced into Nicotiana plumbaginifolia by cocultivation with Agrobacterium tumefaciens [17].
• The expression of the ipt gene was monitored by RNA hybridization, western blotting and cytokinin analysis [13].

References