Anatomical and biochemical changes in the composition of developing seed coats of annatto (Bixa orellana L.)
Contribuinte(s) |
UNIVERSIDADE DE SÃO PAULO |
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Data(s) |
20/10/2012
20/10/2012
2009
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Resumo |
Seeds of Bixa orellana (L.) have a sclerified palisade cell layer, which constitutes a natural barrier to water uptake. In fact, newly fully developed B. orellana seeds are highly impermeable to water and thereby dormant. The purpose of this work is to investigate, from a developmental point of view, the histochemical and physical changes in the cell walls of the seed coat that are associated with the water impermeability. Seed coat samples were analyzed by histochemical and polarization microscopy techniques, as well as by fractionation/HPAEC-PAD. For histochemical analysis the tissue samples were fixed, dehydrated, embedded in paraffin and the slides were dewaxed and tested with appropriate stains for different cell wall components. Throughout the development of B. orellana seeds, there was a gradual thickening of the seed coat at the palisade region. This thickening was due to the deposition of cellulose and hemicelluloses in the palisade layer cell walls, which resulted in a highly water impermeable seed coat. The carbohydrate composition of the cell walls changed dramatically at the late developmental stages due to the intense deposition of hemicelluloses. Hemicelluloses were mainly deposited in the outer region of the palisade layer cell walls and altered the birefringent pattern of the walls. Xylans were by far the most abundant hemicellulosic component of the cell walls. Deposition of cellulose and hemicelluloses, especially xylans, could be responsible for the impermeability to water observed in fully developed B. orellana seeds. Brazilian Coordination (CAPES) Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) Brazilian Council of Research (CNPq) |
Identificador |
TREES-STRUCTURE AND FUNCTION, v.23, n.2, p.287-293, 2009 0931-1890 http://producao.usp.br/handle/BDPI/27311 10.1007/s00468-008-0276-x |
Idioma(s) |
eng |
Publicador |
SPRINGER |
Relação |
Trees-structure and Function |
Direitos |
restrictedAccess Copyright SPRINGER |
Palavras-Chave | #Dormancy #Impermeability #Xylans #Birefringence #Cell walls #IMPOSED DORMANCY #CELL-WALLS #WATER #CELLULOSE #WOOD #ULTRASTRUCTURE #IMPERMEABILITY #PROTEASES #CALLOSE #Forestry |
Tipo |
article original article publishedVersion |