Expression of a human tRNA isopentenyltransferase in tobacco reveals a developmental role for tRNA isopentenyladenosine
Anna Golovko A B , Folke Sitbon A , Elisabeth Tillberg A and Björn Nicander A CA Department of Plant Biology and Forest Genetics, Swedish University of Agricultural Sciences, PO Box 7080, S-75007 Uppsala, Sweden.
B Present address: Department of Medical Biochemistry and Microbiology, PO Box 582, Uppsala University, S-75123 Uppsala, Sweden.
C Corresponding author. Email: Bjorn.Nicander@vbsg.slu.se
Functional Plant Biology 34(7) 654-661 https://doi.org/10.1071/FP07004
Submitted: 8 January 2007 Accepted: 16 April 2007 Published: 4 July 2007
Abstract
In addition to their role as plant hormones, cytokinins are also found as structural components in tRNA. Six different tRNA cytokinins have been found in plants, but most other organisms, including humans, have only one–isopentenyladenosine. In an attempt to probe if the different forms have different functionality, we attempted to alter tRNA cytokinin composition by expressing the human tRNA isopentenyltransferase gene (EC 5.1.2.8) in tobacco [Nicotiana tabacum (L.) cv. Wisconsin 38]. The resulting transgenics had ~40% more isopentenyladenosine in tRNA, and an altered phenotype characterised by reduced internode length, increased stem diameter and rigidity, greener leaves, increased axillary bud outgrowth, abnormal flower morphology, and reduced seed viability. The levels of the two other major isoprene adenines of tRNA, cis-zeatin and 2-methyltiolated cis-zeatin, were also increased, but to a lower degree. Nearly all of the increase in isopentenyladenosine was in a single tRNA species. Two quantitatively minor isopentenyladenosine-containing tRNAs had also increased strongly. IPPT: Dimethylallylpyrophosphate:
Additional keywords: isopentenyladenosine, tRNA modification.
Acknowledgements
We thank Dr Maria Shishova for excellent help with the characterisation of the phenotype. This work was supported by grants from the Trygger Foundation and the Nilsson-Ehle foundation.
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