Abstract
Cytokinins exported from the root may be involved in the correlative control of plant development. To test this hypothesis in soybean ((Glycine max [L.] Merr. cv. McCall, cv Chippewa 64, and cv Hodgson 78), cytokinins were intercepted en route from the root to the shoot by collecting root pressure exudate from detopped roots. The quantities of four cytokinins in the exudate were studied throughout the development of plants grown in the field and in controlled environment chambers. Zeatin, zeatin riboside, and their dihydro derivatives, dihydrozeatin and dihydrozeatin riboside, were isolated and quantitated using high-performance liquid chromatography.
Cytokinin fluxes (pmoles per plant per hour) were independent of exudate flux (grams per plant per hour). All fluxes are averages for a 6- or 8-h collection period. The ribosides accounted for the majority of the observed cytokinin transport. The fluxes of zeatin riboside and dihydrozeatin riboside increased from low levels during vegetative growth to maxima during late flowering or early pod formation. Before the seeds began rapid dry matter accumulation, zeatin riboside and dihydrozeatin riboside fluxes decreased and remained at low levels through maturation. The fluxes of zeatin and dihydrozeatin were low throughout development.
No correlation was found between cytokinin fluxes and nodule dry weight or specific nodule activity (acetylene reduction).
The timing of distinct peaks in zeatin riboside and dihydrozeatin riboside fluxes during flowering or pod formation suggests that cytokinins exported from the root may function in the regulation of reproductive growth in soybean.
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Selected References
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- Beever J. E., Woolhouse H. W. Increased cytokinin from root system of Perilla frutescens and flower and fruit development. Nat New Biol. 1973 Nov 7;246(149):31–32. doi: 10.1038/newbio246031a0. [DOI] [PubMed] [Google Scholar]
- Carmi A., Koller D. Regulation of Photosynthetic Activity in the Primary Leaves of Bean (Phaseolus vulgaris L.) by Materials Moving in the Water-conducting System. Plant Physiol. 1979 Aug;64(2):285–288. doi: 10.1104/pp.64.2.285. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Leonard N. J., Hecht S. M., Skoog F., Schmitz R. Y. Cytokinins: synthesis, mass spectra, and biological activity of compounds related to zeatin. Proc Natl Acad Sci U S A. 1969 May;63(1):175–182. doi: 10.1073/pnas.63.1.175. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Wareing P. F., Khalifa M. M., Treharne K. J. Rate-limiting processes in photosynthesis at saturating light intensities. Nature. 1968 Nov 2;220(5166):453–457. doi: 10.1038/220453a0. [DOI] [PubMed] [Google Scholar]