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. 1982 Jul;70(1):173–178. doi: 10.1104/pp.70.1.173

Cytokinin Structure-Activity Relationships and the Metabolism of N6-(Δ2-Isopentenyl)Adenosine-8-14C in Phaseolus Callus Tissues 1

Machteld C Mok 1,2,3, David W S Mok 1,2,3, Susan C Dixon 1,2,3, Donald J Armstrong 1,2,3, Gordon Shaw 1,2,3
PMCID: PMC1067107  PMID: 16662440

Abstract

The activities of the free base and ribonucleoside forms of cytokinins bearing saturated and unsaturated N6-isoprenoid side chains have been examined in callus cultures derived from Phaseolus vulgaris cv. Great Northern, P. lunatus cv. Kingston, and the interspecific hybrid Great Northern × Kingston. In callus of cv. Great Northern, cytokinins bearing saturated side chains (N6-isopentyladenine, N6-isopentyladenosine, dihydrozeatin, and ribosyldihydrozeatin) were always more active than the corresponding unsaturated analogs (N6-[Δ2-isopentenyl]adenine, N6-[Δ2-isopentenyl]adenosine, zeatin, and ribosylzeatin). In callus of cv. Kinston, the cytokinins bearing unsaturated side chains were either more active or equally as active as the saturated compounds. These differences in cytokinin structure-activity relationships were correlated with differences in the metabolism of 14C-N6-(Δ2-isopentenyl)adenosine. In Great Northern tissues, this cytokinin was rapidly degraded to adenosine; in Kingston tissues, the major metabolite was the corresponding nucleotide. The growth responses of callus of the interspecific hybrid were intermediate between the parental tissues, and the metabolism of 14C-N6-(Δ2-isopentenyl)adenosine by the hybrid callus exhibited characteristics of both parental tissues. The results are consistent with the hypothesis that the weak activity of cytokinins with unsaturated side chains in promoting the growth of Great Northern callus is due to the rapid conversion of these cytokinins to inactive metabolites.

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Selected References

These references are in PubMed. This may not be the complete list of references from this article.

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