This Article Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Email this article to a friend Similar articles in this journal Similar articles in Web of Science 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 CrossRef Citing Articles via Web of Science (62) Citing Articles via Google Scholar Google Scholar Articles by Pharis, R. P. Articles by Mander, L. N. Search for Related Content PubMed PubMed Citation Articles by Pharis, R. P. Articles by Mander, L. N. Agricola Articles by Pharis, R. P. Articles by Mander, L. N.

Development and Growth Regulation

Gibberellins, Endogenous and Applied, in Relation to Flower Induction in the Long-Day Plant Lolium temulentum¹

Plant Physiology Research Group, Department of Biology, University of Calgary, Calgary, Alberta, Canada T2N 1N4, CSIRO Division of Plant Industry, Canberra, ACT 2601 Australia, Research School of Chemistry, Australian National University, Canberra, ACT, 2601 Australia

Changes in endogenous gibberellin-like substances (GAs) and related compounds in the shoot apices of Lolium temulentum during and after flower induction by one long day was examined for plants grown in three consecutive years. The total GA level in the shoot apical tissue was high (up to 42 micrograms per gram dry weight, or 3 x 10^–5 molar GA₃ equivalents), increasing several-fold on the day after the long day and then declining. Of the many GA-like substances present, the putative polyhydroxylated components—with HPLC retention times between those of GA₈ (three hydroxyls) and GA₃₂ (four hydroxyls), and accounting for about a quarter of the total GA activity—were most consistent and striking in their changes. Their level in the apices increased 3- to 5-fold on the day after the long day and then subsided. When various GAs were applied to plants in noninductive short days, flower initiation was induced by several, most notably by GA₃₂, GA₅, 2,2-dimethyl GA₄, GA₃, and GA₇. GA₃₂ was most like one long day in eliciting a strong flowering response while having little effect on stem growth, whereas GA₁ had the opposite effect. It is suggested that highly hydroxylated C-19 GAs may play a central role in the induction of flowering in this long-day plant.

This article has been cited by other articles:

				Y. Kobayashi and D. Weigel Move on up, it's time for change mobile signals controlling photoperiod-dependent flowering Genes & Dev., October 1, 2007; 21(19): 2371 - 2384. [Abstract] [Full Text] [PDF]

				L. Gallego-Giraldo, J. L. Garcia-Martinez, T. Moritz, and I. Lopez-Diaz Flowering in Tobacco Needs Gibberellins but is not Promoted by the Levels of Active GA1 and GA4 in the Apical Shoot Plant Cell Physiol., June 1, 2007; 48(6): 897 - 898. [Full Text] [PDF]

				L. Gallego-Giraldo, J. L. Garcia-Martinez, T. Moritz, and I. Lopez-Diaz Flowering in Tobacco Needs Gibberellins but is not Promoted by the Levels of Active GA1 and GA4 in the Apical Shoot Plant Cell Physiol., April 1, 2007; 48(4): 615 - 625. [Abstract] [Full Text] [PDF]

				M. A. Blazquez, M. Trenor, and D. Weigel Independent Control of Gibberellin Biosynthesis and Flowering Time by the Circadian Clock in Arabidopsis Plant Physiology, December 1, 2002; 130(4): 1770 - 1775. [Abstract] [Full Text] [PDF]

				R. W. King, T. Moritz, L. T. Evans, O. Junttila, and A. J. Herlt Long-Day Induction of Flowering in Lolium temulentum Involves Sequential Increases in Specific Gibberellins at the Shoot Apex Plant Physiology, October 1, 2001; 127(2): 624 - 632. [Abstract] [Full Text] [PDF]

				D. B. Scott, W. Jin, H. K. Ledford, H.-S. Jung, and M. A. Honma EAF1 Regulates Vegetative-Phase Change and Flowering Time in Arabidopsis Plant Physiology, July 1, 1999; 120(3): 675 - 684. [Abstract] [Full Text]

				G. F.W. Gocal, A. T. Poole, F. Gubler, R. J. Watts, C. Blundell, and R. W. King Long-Day Up-Regulation of a GAMYB Gene during Lolium temulentum Inflorescence Formation Plant Physiology, April 1, 1999; 119(4): 1271 - 1278. [Abstract] [Full Text]

				A Telfer, K. Bollman, and R. Poethig Phase change and the regulation of trichome distribution in Arabidopsis thaliana Development, January 2, 1997; 124(3): 645 - 654. [Abstract] [PDF]

				J. K. Okamuro, B. G. W. den Boer, C. Lotys-Prass, W. Szeto, and K. D. Jofuku Flowers into shoots: Photo and hormonal control of a meristem identity switch in Arabidopsis PNAS, November 26, 1996; 93(24): 13831 - 13836. [Abstract] [Full Text] [PDF]

				C. McDaniel and L. Hartnett Flowering as metamorphosis: two sequential signals regulate floral initiation in Lolium temulentum Development, January 11, 1996; 122(11): 3661 - 3668. [Abstract] [PDF]