Isolation and Characterization of Arabidopsis Mutants Defective in the Induction of Ethylene Biosynthesis by Cytokinin

Corresponding author: Joseph J. Kieber, University of Illinois at Chicago, Molecular Biology Research Facility, Laboratory for Molecular Biology (M/C 567), 900 S. Ashland Ave., Chicago, IL 60607, jkieber{at}uic.edu (E-mail).

Communicating editor: J. CHORY

Cytokinins elevate ethylene biosynthesis in etiolated Arabidopsis seedlings via a post-transcriptional modification of one isoform of the key biosynthetic enzyme ACC synthase. In order to begin to dissect the signaling events leading from cytokinin perception to this modification, we have isolated a series of mutants that lack the ethylene-mediated triple response in the presence of cytokinin due to their failure to increase ethylene biosynthesis. Analysis of genetic complementation and mapping revealed that these Cin mutants (cytokinin-insensitive) represent four distinct complementation groups, one of which, cin4, is allelic to the constitutive photomorphogenic mutant fus9/cop10. The Cin mutants have subtle effects on the morphology of adult plants. We further characterized the Cin mutants by analyzing ethylene biosynthesis in response to various other inducers and in adult tissues, as well as by assaying additional cytokinin responses. The cin3 mutant did not disrupt ethylene biosynthesis under any other conditions, nor did it disrupt any other cytokinin responses. Only cin2 disrupted ethylene biosynthesis in multiple circumstances. cin1 and cin2 made less anthocyanin in response to cytokinin. cin1 also displayed reduced shoot initiation in tissue culture in response to cytokinin, suggesting that it affects a cytokinin signaling element.

This article has been cited by other articles:

				J. P.C. To, J. Deruere, B. B. Maxwell, V. F. Morris, C. E. Hutchison, F. J. Ferreira, G. E. Schaller, and J. J. Kieber Cytokinin Regulates Type-A Arabidopsis Response Regulator Activity and Protein Stability via Two-Component Phosphorelay PLANT CELL, December 1, 2007; 19(12): 3901 - 3914. [Abstract] [Full Text] [PDF]

				B. Hou, E.-K. Lim, G. S. Higgins, and D. J. Bowles N-Glucosylation of Cytokinins by Glycosyltransferases of Arabidopsis thaliana J. Biol. Chem., November 12, 2004; 279(46): 47822 - 47832. [Abstract] [Full Text] [PDF]

				B. Chow and P. McCourt Hormone signalling from a developmental context J. Exp. Bot., January 2, 2004; 55(395): 247 - 251. [Abstract] [Full Text] [PDF]

				C. E. Hutchison and J. J. Kieber Cytokinin Signaling in Arabidopsis PLANT CELL, May 1, 2002; 14(90001): S47 - 59. [Full Text] [PDF]

				K. L.-C. Wang, H. Li, and J. R. Ecker Ethylene Biosynthesis and Signaling Networks PLANT CELL, May 1, 2002; 14(90001): S131 - 151. [Full Text] [PDF]

				G. Suzuki, Y. Yanagawa, S. F. Kwok, M. Matsui, and X.-W. Deng Arabidopsis COP10 is a ubiquitin-conjugating enzyme variant that acts together with COP1 and the COP9 signalosome in repressing photomorphogenesis Genes & Dev., March 1, 2002; 16(5): 554 - 559. [Abstract] [Full Text] [PDF]

				W. Schmidt, J. Tittel, and A. Schikora Role of Hormones in the Induction of Iron Deficiency Responses in Arabidopsis Roots Plant Physiology, April 1, 2000; 122(4): 1109 - 1118. [Abstract] [Full Text]

				K. E. Woeste and J. J. Kieber A Strong Loss-of-Function Mutation in RAN1 Results in Constitutive Activation of the Ethylene Response Pathway as Well as a Rosette-Lethal Phenotype PLANT CELL, March 1, 2000; 12(3): 443 - 455. [Abstract] [Full Text]

				K. E. Woeste, C. Ye, and J. J. Kieber Two Arabidopsis Mutants That Overproduce Ethylene Are Affected in the Posttranscriptional Regulation of 1-Aminocyclopropane-1-Carboxylic Acid Synthase Plant Physiology, February 1, 1999; 119(2): 521 - 530. [Abstract] [Full Text]

				I. Brandstatter and J. J. Kieber Two Genes with Similarity to Bacterial Response Regulators Are Rapidly and Specifically Induced by Cytokinin in Arabidopsis PLANT CELL, June 1, 1998; 10(6): 1009 - 1020. [Abstract] [Full Text]