The response of a cytokinin resistant mutant is highly specific and permits a new cytokinin bioassay

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Nogué, Fabien, F. | Jullien, M. | Mornet, R. | Laloue, M.

Edité par CCSD ; Springer Verlag -

International audience. We have previously isolated six independent cytokinin-resistant mutants of Nicotiana plumbaginifolia which define three complementation groups, zea1, zea2 and zea3. We report here the characterization of the phenotypic response to cytokinin treatment of the mutant 1-64, belonging to the zeal group, and the result of the study of the specificity of this response. The phenotype of this mutant grown in the presence of cytokinin concentrations higher than 0.1 mu M is characterized by a hypertrophy of the cotyledons and hypocotyl which results in an increase of plantlet fresh weight. This hypertrophy is correlated to cytokinin concentration in a range between 0.01 to 10 mu M. The specificity of this response has been verified by using adenine and urea type cytokinins, as well as enantiomers of methylzeatin and methylbenzyladenine which differ widely in their cytokinin activities. We show that the high specificity of the hypertrophic response to cytokinins can be used as a convenient bioassay to screen the cytokinin activity of adenine or urea type molecules.

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