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Inhibition ofEnt-kaurene oxidation by cytokinins

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Abstract

Cytokinins, which have some structural similarities to ancymidol, a plant growth retardant, were tested for their effects on the cell-free oxidation ofent-kaurene. Results indicate that several cytokinins inhibit this reaction in microsomal extracts of liquid endosperm from immature wild cucumber seeds. N6-cyclohexanemethyladenine was the most active (inhibiting 50% of the controlent-kaurene oxidation at 2×10−6 M). N6-isoamyladenine, N6-benzyladenine, N6-(Δ2-isopentenyl)adenine and dihydrozeatin were active at successively higher concentrations. Zeatin, kinetin, adenine, N6-benzyladenosine, and N6-(isopentenyl)adenosine were inactive in this system.

The basis for the inhibition ofent-kaurene oxidation by cytokinins may be similar to that of ancymidol: interaction with cytochrome P-450. A binding spectrum similar to that of ancymidol with cytochrome P-450 from wild cucumber endosperm microsomes was obtained with four active cytokinins. The cytokinin binding properties of this protein are currently under investigation.

No metabolism of N6-benzyladenine could be detected under conditions in which the cytokinin inhibited the oxidation ofent-kaurene toent-kaurenol.

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Abbreviations

Ancymidol:

α-cyclopropyl-α-(p-methoxyphenyl)-5-pyrimidine methyl alcohol

EL-509:

the α-isopropyl derivative of ancymidol (see Coolbaugh et al. 1982)

ent-Kaurene:

ent-kaur-16-ene

ent-kaurenol:

ent-kaur-16-en-19-ol

isopentenyladenine:

N6-(Δ2-isopentenyl)adenine

benzyladenine:

N6-benzylaminopurine

kinetin:

6-(furfurylamino)purine

zeatin:

6-(4-hydroxy-3-methyl-trans-2-butenylamino) purine

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Authors and Affiliations

  1. Department of Botany, Iowa State University, 50010, Ames, Iowa, USA

    Ronald C. Coolbaugh

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  1. Ronald C. Coolbaugh
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Additional information

This work was supported in part by National Science Foundation Grant PCM 7619279 and PCM 8016237, and a grant from Eli Lilly and Company.

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Coolbaugh, R.C. Inhibition ofEnt-kaurene oxidation by cytokinins. J Plant Growth Regul 3, 97–109 (1984). https://doi.org/10.1007/BF02041995

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  • DOI: https://doi.org/10.1007/BF02041995

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