Present address: Department of Plant Molecular Biology, University of Lausanne, Biophore Building, CH–1015 Lausanne, Switzerland.
Fertilization-dependent auxin response in ovules triggers fruit development through the modulation of gibberellin metabolism in Arabidopsis
Article first published online: 21 JAN 2009
© 2009 The Authors. Journal compilation © 2009 Blackwell Publishing Ltd
The Plant Journal
Volume 58, Issue 2, pages 318–332, April 2009
How to Cite
Dorcey, E., Urbez, C., Blázquez, M. A., Carbonell, J. and Perez-Amador, M. A. (2009), Fertilization-dependent auxin response in ovules triggers fruit development through the modulation of gibberellin metabolism in Arabidopsis. The Plant Journal, 58: 318–332. doi: 10.1111/j.1365-313X.2008.03781.x
- Issue published online: 8 APR 2009
- Article first published online: 21 JAN 2009
- Received 28 October 2008; revised 4 December 2008; accepted 8 December 2008; published online 21 January 2009.
Fruit development is usually triggered by ovule fertilization, and it requires coordination between seed development and the growth and differentiation of the ovary to host the seeds. Hormones are known to synchronize these two processes, but the role of each hormone, and the mechanism by which they interact, are still unknown. Here we show that auxin and gibberellins (GAs) act in a hierarchical scheme. The synthetic reporter construct DR5:GFP showed that fertilization triggered an increase in auxin response in the ovules, which could be mimicked by blocking polar auxin transport. As the application of GAs did not affect auxin response, the most likely sequence of events after fertilization involves auxin-mediated activation of GA synthesis. We have confirmed this, and have shown that GA biosynthesis upon fertilization is localized specifically in the fertilized ovules. Furthermore, auxin treatment caused changes in the expression of GA biosynthetic genes similar to those triggered by fertilization, and also restricted to the ovules. Finally, GA signaling was activated in ovules and valves, as shown by the rapid downregulation of the fusion protein RGA-GFP after pollination and auxin treatment. Taken together, this evidence suggests a model in which fertilization would trigger an auxin-mediated promotion of GA synthesis specifically in the ovule. The GAs synthesized in the ovules would be then transported to the valves to promote GA signaling and thus coordinate growth of the silique.