HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Full Text Full Text (PDF) Submit a response Alert me when this article is cited Alert me when eLetters are posted Alert me if a correction is posted Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via ISI Web of Science (10) Citing Articles via Google Scholar Google Scholar Articles by Christianson, M. L. Articles by Hornbuckle, J. S. Search for Related Content PubMed PubMed Citation Articles by Christianson, M. L. Articles by Hornbuckle, J. S. Agricola Articles by Christianson, M. L. Articles by Hornbuckle, J. S.

Phenylurea cytokinins assayed for induction of shoot buds in the moss Funaria hygrometrica¹

Division of Biological Sciences, Department of Ecology and Evolutionary Biology, University of Kansas,Lawrence, Kansas 66045

The induction of shoot buds from the filamentous protonema of moss is a classic bioassay for cytokinin. While a large literature documents this response in many species of moss and for a wide range of natural and synthetic cytokinins, to date only substituted adenine cytokinins have been examined in detail. This paper shows that at least some of the novel phenylurea cytokinins will induce bud formation in mosses. Funaria responds to thidiazuron much as it responds to benzyladenine. Exposure to either substance results in log-linear dose-dependent increases in bud number that reach similar maximal numbers of buds at the optimal concentration of compound. The related compound chloro-pyridyl-phenylurea (CPPU) is slightly less active, but induces buds over a wider range of concentration. Carbanilide (diphenylurea or DPU), an active cytokinin in other systems, induces very few buds in Funaria, but does so over a wide range of concentration. Bioassay of mixtures of benzyladenine and DPU finds no evidence of competition for cytokinin receptors. That result could support suggestions that the phenylurea cytokinins act indirectly, by altering endogenous cytokinin metabolism, but we favor another interpretation. Unlike other cytokinin-responsive systems, the induction of buds from moss protonema involves two cytokinin-mediated events. The number of buds is controlled by the second cytokinin-mediated event. If DPU has little or no affinity for the receptor triggering this second event, DPU treatments will produce few to no buds, and kinetic analysis using bud number would find no evidence for competition with benzyladenine. Our results would support the hypothesis that bud induction in Funaria involves two chemically distinct cytokinin receptors.

Key Words: bud formation • cytokinin • Funaria hygrometrica • moss • phenylurea • plant developmental biology

This article has been cited by other articles:

				M. L. Christianson ABA prevents the second cytokinin-mediated event during the induction of shoot buds in the moss Funaria hygrometrica Am. J. Botany, October 1, 2000; 87(10): 1540 - 1545. [Abstract] [Full Text]