AOBPreview originally published online on September 21, 2009
Annals of Botany 2009 104(6):1111-1119; doi:10.1093/aob/mcp212
| ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
The role of carbohydrates in seed germination and seedling establishment of Himatanthus sucuuba, an Amazonian tree with populations adapted to flooded and non-flooded conditions
1 Instituto Nacional de Pesquisas da Amazônia (INPA), Projeto INPA/Max-Planck, 69011-970, Manaus, Brazil
2 Department of Botany, University of Brasilia, Brasilia, DF, 70904-970, Brazil
3 Instituto de Botânica, Seção de Fisiologia e Bioquímica de Plantas, São Paulo, SP, 04301-012, Brazil
4 Biocentre Klein Flottbek, Dept of Plant Systematics, University of Hamburg, Germany
5 Universidade de São Paulo, Instituto de Biociências, Departamento de Botânica, São Paulo, SP, 05422-970, Brazil
* Corresponding author. E-mail msbuck{at}usp.br
Received: 11 April 2009 Returned for revision: 22 May 2009 Accepted: 20 July 2009 Published electronically: 21 September 2009
Background and Aims: In the Amazonian floodplains plants withstand annual periods of flooding which can last 7 months. Under these conditions seedlings remain submerged in the dark for long periods since light penetration in the water is limited. Himatanthus sucuuba is a tree species found in the ‘várzea’ (VZ) floodplains and adjacent non-flooded ‘terra-firme’ (TF) forests. Biochemical traits which enhance flood tolerance and colonization success of H. sucuuba in periodically flooded environments were investigated.
Methods: Storage carbohydrates of seeds of VZ and TF populations were extracted and analysed by HPAEC/PAD. Starch was analysed by enzyme (glucoamylase) degradation followed by quantification of glucose oxidase. Carbohydrate composition of roots of VZ and TF seedlings was studied after experimental exposure to a 15-d period of submersion in light versus darkness.
Key Results: The endosperm contains a large proportion of the seed reserves, raffinose being the main non-structural carbohydrate. Around 93 % of the cell wall storage polysaccharides (percentage dry weight basis) in the endosperm of VZ seeds was composed of mannose, while soluble sugars accounted for 2·5%. In contrast, 74 % of the endosperm in TF seeds was composed of galactomannans, while 22 % of the endosperm was soluble sugars. This suggested a larger carbohydrate allocation to germination in TF populations whereas VZ populations allocate comparatively more to carbohydrates mobilized during seedling development. The concentration of root non-structural carbohydrates in non-flooded seedlings strongly decreased after a 15-d period of darkness, whereas flooded seedlings were less affected. These effects were more pronounced in TF seedlings, which showed significantly lower root non-structural carbohydrate concentrations.
Conclusions: There seem to be metabolic adjustments in VZ but not TF seedlings that lead to adaptation to the combined stresses of darkness and flooding. This seems to be important for the survival of the species in these contrasting environments, leading these populations to different directions during evolution.
Key words: Carbohydrate reserves, Himatanthus sucuuba, submergence tolerance, floodplains, galactomannans, raffinose, population differentiation, Amazon, storage
CiteULike 
Connotea 
Del.icio.us What's this?
Related articles in Ann Bot:
- ContentSnapshots
Ann Bot 2009 104: i.[Extract] [Full Text]