Journal Article

Plants with Increased Expression of <i>ent</i>-Kaurene Oxidase are Resistant to Chemical Inhibitors of this Gibberellin Biosynthesis Enzyme

Stephen M. Swain, Davinder P. Singh, Chris A. Helliwell and Andrew T. Poole

in Plant and Cell Physiology

Published on behalf of Japanese Society of Plant Physiologists

Volume 46, issue 2, pages 284-291
Published in print February 2005 | ISSN: 0032-0781
Published online February 2005 | e-ISSN: 1471-9053 | DOI: http://dx.doi.org/10.1093/pcp/pci027
Plants with Increased Expression of ent-Kaurene Oxidase are Resistant to Chemical Inhibitors of this Gibberellin Biosynthesis Enzyme

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  • Biochemistry
  • Molecular and Cell Biology
  • Plant Sciences and Forestry

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The gibberellin (GA) biosynthetic pathway includes the three-step oxidation of ent-kaurene to ent-kaurenoic acid, catalyzed by the enzyme ent-kaurene oxidase (KO). Arabidopsis plants overexpressing the KO cDNA under the control of the cauliflower mosaic virus 35S promoter, with or without a translational fusion to a modified green fluorescent protein (GFP), are very similar to wild-type (WT) plants under normal growth conditions. In contrast, when WT and 35S:KO (or 35S:KO–GFP) seeds, seedlings or pollen tubes are grown in the presence of chemical inhibitors of KO, such as paclobutrazol and uniconazole, plants with increased KO expression are partially resistant to the effects of these inhibitors. In combination with the observation that decreased KO levels increase the sensitivity to KO inhibitors, the 35S:KO phenotypes demonstrate that the modification of KO enzyme levels could be used to create transgenic crop plants with altered KO inhibitor response. These results also suggest that the KO gene could be used as a selectable marker for plant regeneration based on resistance to KO inhibitors. Finally, the observation that pollen tubes expressing 35S:KO or 35S:KO–GFP have decreased sensitivity to KO inhibitors provides further evidence for a physiological role for GAs in pollen tube elongation.

Keywords: Arabidopsis; ent-kaurene oxidase; Gibberellin; Pollen tubes; Plant growth regulator; CPS, ent-copalyl diphosphate synthase; GA, gibberellin; GC-SIM, gas chromatography-selected ion monitoring; GFP, green fluorescent protein; KO, ent-kaurene oxidase; KS, ent-kaurene synthase; WT, wild-type

Journal Article.  5550 words.  Illustrated.

Subjects: Biochemistry ; Molecular and Cell Biology ; Plant Sciences and Forestry

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