Ectopic expression of maize knotted1 results in the cytokinin-autotrophic growth of cultured tobacco tissues |
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Authors: | Andreas Hewelt Els Prinsen Monique Thomas Harry Van Onckelen Frederick Meins Jr |
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Institution: | (1) Friedrich Miescher Institute, a branch of the Novartis Research Foundation, Naulbeerstrasse 66, 4058 Basel, Switzerland, CH;(2) University of Antwerp (UIA), Department of Biology, Universiteitsplein 1, 2610 Antwerp, Belgium, BE |
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Abstract: | The ectopic expression of knotted homologues has cytokinin-like effects on plant morphology. The functional relationship between knotted and cytokinins was investigated in cultures of leaf tissue established from tobacco (Nicotiana tabacum L. cv. Havana 425) plants transformed with the maize knotted1 (kn1) gene regulated by cauliflower mosaic virus 35S RNA expression signals. In contrast to leaf tissues of untransformed plants,
leaf tissues of kn1 transformants were capable of sustained, cytokinin-autotrophic growth on auxin-containing medium and resembled the tobacco
cytokinin-autotrophic mutants Hl-1 and Hl-2. The concentration of 18 cytokinins was measured in cultures initiated from leaves of three independent kn1 transformants and the Hl-1 and Hl-2 mutants. Although cytokinin contents were variable, the content of several cytokinins in Kn1, Hl-1 and Hl-2 tissue lines was at least 10-fold higher than that of wild-type tobacco tissues and in the range reported for other cytokinin-autotrophic
tobacco tissues. These results suggest that the cytokinin-autotrophic growth of Kn1 lines could result from elevated steady-state levels of cytokinins.
Received: 7 July 1999 / Accepted: 10 November 1999 |
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Keywords: | : Cytokinin – Habituation – Hormone autotrophy – Knotted1– Nicotiana– Tissue culture |
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