Abstract
In Nicotiana plumbaginifolia cytokinins affect seedling development by inhibiting root growth and hypocotyl elongation and by stimulating cotyledon expansion. The zea3.1 mutant was selected for its inability to grow in conditions of low nitrogen and for its ability to grow independently on inhibitory concentrations of zeatin (J.D. Faure, M. Jullien, M. Caboche [1994] Plant J 5: 481-491). The zea3.1 growth response to cytokinins is reflected by an increase in cotyledon expansion due to cell division and by a swelling of the hypocotyl due to cell enlargement. An analysis of the seedling's root length and fresh weight over a wide range of benzyladenine concentrations showed that zea3.1 plants exhibit a higher sensitivity and an amplified response to cytokinins. A similar response of zea3.1 to benzyladenine was also seen in the expression of msr1, a cytokinin-regulated gene. Regulation of msr1 expression by protein phosphorylation was unaffected by the zea3.1 mutation. No significant differences in cytokinin and auxin levels were found between zea3.1 and wild-type seedlings, suggesting that the mutant phenotype is not caused by an alteration of these hormone levels. The data presented suggest that ZEA3 negatively modulates cytokinin responses and may function as a broad regulator of seedling development.
Full Text
The Full Text of this article is available as a PDF (2.8 MB).
Selected References
These references are in PubMed. This may not be the complete list of references from this article.
- Baskin T. I., Cork A., Williamson R. E., Gorst J. R. STUNTED PLANT 1, A Gene Required for Expansion in Rapidly Elongating but Not in Dividing Cells and Mediating Root Growth Responses to Applied Cytokinin. Plant Physiol. 1995 Jan;107(1):233–243. doi: 10.1104/pp.107.1.233. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Boutry M., Chua N. H. A nuclear gene encoding the beta subunit of the mitochondrial ATP synthase in Nicotiana plumbaginifolia. EMBO J. 1985 Sep;4(9):2159–2165. doi: 10.1002/j.1460-2075.1985.tb03910.x. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Cary A. J., Liu W., Howell S. H. Cytokinin action is coupled to ethylene in its effects on the inhibition of root and hypocotyl elongation in Arabidopsis thaliana seedlings. Plant Physiol. 1995 Apr;107(4):1075–1082. doi: 10.1104/pp.107.4.1075. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Chory J., Aguilar N., Peto C. A. The phenotype of Arabidopsis thaliana det1 mutants suggests a role for cytokinins in greening. Symp Soc Exp Biol. 1991;45:21–29. [PubMed] [Google Scholar]
- Chory J., Reinecke D., Sim S., Washburn T., Brenner M. A Role for Cytokinins in De-Etiolation in Arabidopsis (det Mutants Have an Altered Response to Cytokinins). Plant Physiol. 1994 Feb;104(2):339–347. doi: 10.1104/pp.104.2.339. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Deikman J., Ulrich M. A novel cytokinin-resistant mutant of Arabidopsis with abbreviated shoot development. Planta. 1995;195(3):440–449. doi: 10.1007/BF00202603. [DOI] [PubMed] [Google Scholar]
- Dias M., Mornet R., Laloue M. Synthesis, azido-tetrazole equilibrium studies and biological activity of 1-(2-azido-6-chloropyrid-4-yl)-3-phenylurea, a photoaffinity labeling reagent for cytokinin-binding proteins. Bioorg Med Chem. 1995 Apr;3(4):361–366. doi: 10.1016/0968-0896(95)00035-f. [DOI] [PubMed] [Google Scholar]
- Dominov J. A., Stenzler L., Lee S., Schwarz J. J., Leisner S., Howell S. H. Cytokinins and auxins control the expression of a gene in Nicotiana plumbaginifolia cells by feedback regulation. Plant Cell. 1992 Apr;4(4):451–461. doi: 10.1105/tpc.4.4.451. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Faure J. D., Jullien M., Caboche M. Zea3: a pleiotropic mutation affecting cotyledon development, cytokinin resistance and carbon-nitrogen metabolism. Plant J. 1994 Apr;5(4):481–491. doi: 10.1046/j.1365-313x.1994.5040481.x. [DOI] [PubMed] [Google Scholar]
- Haystead T. A., Sim A. T., Carling D., Honnor R. C., Tsukitani Y., Cohen P., Hardie D. G. Effects of the tumour promoter okadaic acid on intracellular protein phosphorylation and metabolism. Nature. 1989 Jan 5;337(6202):78–81. doi: 10.1038/337078a0. [DOI] [PubMed] [Google Scholar]
- Julliard J., Sotta B., Pelletier G., Miginiac E. Enhancement of Naphthaleneacetic Acid-Induced Rhizogenesis in T(L)-DNA-Transformed Brassica napus without Significant Modification of Auxin Levels and Auxin Sensitivity. Plant Physiol. 1992 Nov;100(3):1277–1282. doi: 10.1104/pp.100.3.1277. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Kay R., Chan A., Daly M., McPherson J. Duplication of CaMV 35S Promoter Sequences Creates a Strong Enhancer for Plant Genes. Science. 1987 Jun 5;236(4806):1299–1302. doi: 10.1126/science.236.4806.1299. [DOI] [PubMed] [Google Scholar]
- Rayle D. L., Ross C. W., Robinson N. Estimation of osmotic parameters accompanying zeatin-induced growth of detached cucumber cotyledons. Plant Physiol. 1982 Dec;70(6):1634–1636. doi: 10.1104/pp.70.6.1634. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Su W., Howell S. H. A Single Genetic Locus, Ckr1, Defines Arabidopsis Mutants in which Root Growth Is Resistant to Low Concentrations of Cytokinin. Plant Physiol. 1992 Aug;99(4):1569–1574. doi: 10.1104/pp.99.4.1569. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Yip W. K., Yang S. F. Effect of thidiazuron, a cytokinin-active urea derivative, in cytokinin-dependent ethylene production systems. Plant Physiol. 1986 Feb;80(2):515–519. doi: 10.1104/pp.80.2.515. [DOI] [PMC free article] [PubMed] [Google Scholar]