Endogenous cytokinins in the vascular cambial region of Pinus sylvestris during activity and dormancy |
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Authors: | Thomas Moritz Björn Sundberg |
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Institution: | Dept of Forest Genetics and Plant Physiology, Swedish Univ. of Agricultural Sciences, S-901 83 Umeå, Sweden. |
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Abstract: | Elucidation of the role of endogenous cytokinins in cambial activity and wood formation requires knowledge of their identity and concentrations in the cambial region. Here, we have used capillary liquid chromatography/frit-FAB mass spectrometry to identify endogenous cytokinins in the vascular cambial region of mature Pinus sylvestris (L.) trees. Full-scan mass spectra were obtained for isopentenyladenine, isopentenyladenosine, zeatin riboside, dihydrozeatin and dihydrozeatin riboside. Of these, isopentenyladenine, dihydrozeatin and dihydrozeatin riboside are demonstrated by rigorous physico chemical methods for the first time in a conifer. In addition, an adenine glycoside was found for the first time in a plant. The identified cytokinins were quantified in active and dormant cambial region tissues by isotope dilution techniques using the appropriate deuterated isotope for each cytokinin species. The concentration of the detected cytokinins ranged between 1.3 and 5.5 pmol g-1 fresh weight, and did not vary greatly between dormant tissues, and in tissues actively dividing and differentiating. This observation indicates that cessation and reactivation of cell division activity in the vascular cambium is controlled by factors other than cytokinin availability. |
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Keywords: | Capillary liquid chromatography/frit-FAB mass spectrometry conifer cytokinins identification Pinus sylvestris Scots pine vascular cambium wood formation xylem |
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