Characterisation of chilean hazelnut (gevuina avellana) tissues : light microscopy and cell wall polysaccharides

• Autor(a) principal: Dourado, Fernando
• Data de Publicação: 2003
• Outros Autores: Vasco, Pedro, Barros, António, Mota, M., Coimbra, Manuel A., Gama, F. M.
• Tipo de documento: Artigo
• Idioma: eng
• Título da fonte: Repositório Científico de Acesso Aberto de Portugal (Repositórios Cientìficos)
• Texto Completo: https://hdl.handle.net/1822/1387
• topic: Hazelnut; Gevuina avellana; Seed structure; Cell walls; Light microscopy; FT-IR; Xyloglucan; Science & Technology

By applying several differential staining techniques and light microscopy, the structure and composition of Chilean hazelnut (Gevuina avellana) seeds were analysed. The structure of the G avellana seed is very simple, with a thin, heavily lignified seed coat and two voluminous cotyledons. The embryo food reserves are uniformly distributed over the cotyledon cells. The cell wall polysaccharides were recovered from the alcohol-insoluble residue by mild treatment with warm chlorite solution and sequential extraction with alkali solutions of increasing concentration. FT-IR spectra in the 1200–850 cm-1 region were used together with chemometric techniques to distinguish the hemicellulosic and pectic polysaccharides in the extracts. The most abundant extracts were fractionated by graded precipitation in ethanol. A xyloglucan was identified by 1H and 13C NMR as the major hemicellulosic polysaccharide, with a sugar composition of 4Glc:3.5Xyl:1Gal:0.5Fuc. The hazelnut cell walls are composed of equivalent amounts of pectic polysaccharides, xyloglucans and cellulose.