Tree Physiology Advance Access originally published online on February 2, 2009
Tree Physiology 2009 29(4):607-620; doi:10.1093/treephys/tpn052
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Shooting control by brassinosteroids: metabolomic analysis and effect of brassinazole on Malus prunifolia, the Marubakaido apple rootstock
1 Department of Botany-SCB, Paraná Federal University, Centro Politecnico, C.P. 19031, 81531-970 Curitiba-Paraná, Brazil
2 Corresponding author (apereira{at}ufpr.br)
3 Australian Centre for Plant Functional Genomics, School of Botany, The University of Melbourne, 3010 Victoria, Australia
4 RIKEN, Wako-shi, Saitama 351-0198, Japan
5 Department of Applied Biological Chemistry, The University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo, Japan
6 Department of Horticultural Science, North Carolina State University, Campus Box 7609, Raleigh, NC 27695-7609, USA
| Abstract |
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To help unravel the role of brassinosteroids (BRs) in the control of shooting, we treated the shoots of Marubakaido apple rootstock (Malus prunifolia (Willd.) Borkh cv. Marubakaido) with brassinolide and Brz 220, an inhibitor of BR biosynthesis. Brassinolide differentially affected elongation and formation of main and primary lateral shoots, which resulted in reduced apical dominance. Treatment of shoots with increasing doses of Brz 220 led to a progressive inhibition of main shoot elongation. Eight different BRs were also identified in the shoots of M. prunifolia. Progressive decline in 6-deoxocathasterone, 6-deoxotyphasterol and castasterone was related to increased doses of Brz 220. Analysis of the metabolic profiles between a fluoro-containing derivative of 28-homocastasterone (5F-HCS) using treated and untreated shoots demonstrated that no 5F-HCS-specific metabolite was identified. However, 4 weeks after the treatment, fructose, glucose and the putatively identified gulonic acid were higher in 5F-HCS-treated shoots, compared to untreated shoots. These results indicate that the previously reported 5F-HCS-induced stimulation of shoot elongation and formation of new shoots in the Marubakaido shoots is under the control of changes in the endogenous BR pool. In addition, the results presented in this report also indicate that the 5F-HCS-induced shooting likely involves a variety of different mechanisms and consequently does not result from changes in the endogenous levels of any single metabolite.
Keywords: endogenous brassinosteroids, homocastasterone, metabolite profiling, shoot elongation
Received October 9, 2008; Accepted December 18, 2008
Supplementary data for this article are available at Tree Physiology Online.