New Zealand Journal of Botany abstract

Cytokinins and the regulation of plant form in three species of Sophora

FIONA E. CARSWELL
JAMIE S. DAY*
KEVIN S. GOULD

Plant Science Group
School of Biological Sciences
The University of Auckland
Private Bag 92019
Auckland, New Zealand
*Present address: Department of Biochemistry, University of Otago, P.O. Box 56, Dunedin, New Zealand.

PAULA E. JAMESON

Department of Botany
University of Otago
P.O. Box 56
Dunedin, New Zealand
Author for correspondence.
Present address: Department of Plant Biology and Biotechnology, Massey University, Private Bag 11222, Palmerston North, New Zealand.

Abstract  Possible relationships between cytokinins and juvenile form of Sophora species were investigated. Exogenous applications of 6-benzylaminopurine (6-BAP) to seedling S. microphylla resulted in a more divaricating appearance. Treated plants had more outgrown branches, wider branch angles, and narrower node angles than control plants. 6-BAP at 50 umol/l concentration was more effective in promoting this change than at a concentration of 150 umol/l. The form of S. prostrata was not altered by exogenous application of cytokinin. Endogenous levels of storage and active cytokinins were assayed in pot-grown material, using high performance liquid chromatography and radioimmunoassay. Compounds with retention times and antibody specificity typical of known cytokinins in other species, were detected in S. microphylla, S. prostrata, and S. tetraptera. The recovery rates were low (1.5-18%) and results are difficult to interpret because of large amounts of an unknown cytokinin. However, it appears that the ratio of active to storage cytokinin is greater in the divaricating than non-divaricating forms.

Keywords  Sophora microphylla; Sophora prostrata; Sophora tetraptera; cytokinin; divaricating habit

Abbreviations  6-BAP = 6-benzylaminopurine, cZ = cis-zeatin, cZR = cis-9-ß-D-ribofuranosylzeatin, dZ = dihydrozeatin, dZ9G = 9-ß-D-glucopyranosyl-(dihydro) zeatin, dZR = 9-ß-D-ribofuranosyl-(dihydro) zeatin, HPLC = high performance liquid chromatography, iP = N6-([[Delta]]²-isopentenyl) adenine, iPA = 9-ß-D-ribofuranosyl-N6-([[Delta]]²-isopentenyl) adenine, iP9G = 9-glucopyranosyl-N6-([[Delta]]²-isopentenyl) adenine, ms-iP = 2-methylthio-N6-([[Delta]]²-isopentenyl) adenine, RIA = radioimmunoassay, Z = zeatin, Z9G = 9-ß-D-glucopyranosylzeatin, ZR = 9-ß-D-ribofuranosylzeatin

B94040

Received 12 September 1994; accepted 20 October 1995

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