Storage reserves and cellular water in mature seeds of Araucaria angustifolia

Seed tissues of Araucaria angustifolia (Bertol.) Kuntze were investigated using histochemistry, transmission electron microscopy (TEM) and energy dispersive X-ray (EDX) analysis. Moisture content and water status in tissues were also evaluated. In the embryo, TEM studies revealed the presence of one to several central vacuoles and a peripheral layer of cytoplasm in cells from different tissues of the cotyledons and axis. In the cytoplasm, lipid bodies, starch grains, mitochondria and a nucleus are evident. In most tissues, vacuoles contain proteins, indicating that the storage proteins are highly hydrated. In cells of the root cap, proteins are stored in discrete protein bodies. Both protein storage vacuoles and discrete protein bodies have inclusions of crystal globoids. EDX analysis of globoids revealed the presence of P, K and Mg as the main constituents and traces of S, Ca and Fe. In the root and shoot meristems, deposits of phytoferritin are present in the stroma of proplastids. The gametophyte consists of cells characterized by relatively thin cell walls and one to several nuclei per cell. Protein and lipid bodies are present, although starch is the most conspicuous reserve. Immediately after shedding, moisture content is approximately 145% (dry weight) for the embryo and 95% (dry weight) for the gametophyte. Calorimetric studies reveal that axes and cotyledons have a very high content of freezable water, corresponding to types 5 and 4, i.e. dilute and concentrated (or capillary) solution, respectively. The results are discussed in relation to the behaviour of the species, which has been categorized as recalcitrant.  © 2002 The Linnean Society of London . Botanical Journal of the Linnean Society , 2002, 140 , 273−281.     

Seed Structure and Localization of Reserves inChenopodium quinoa

The three areas of food reserves in quinoa seeds are: a largecentral perisperm, a peripheral embryo and a one to two-celllayered endosperm surrounding the hypocotyl-radicle axis ofthe embryo. Cytochemical and ultrastructural analysis revealedthat starch grains occupy the cells of the perisperm, whilelipid bodies, protein bodies with globoid crystals of phytin,and proplastids with deposits of phytoferritin are the storagecomponents of the cells of the endosperm and embryo tissues.EDX analysis of the endosperm and embryo protein bodies revealedthat globoid crystals contain phosphorus, potassium and magnesium.These results are compared with studies on other perispermousseeds published to date.Copyright 1998 Annals of Botany Company Chenopodium quinoa,EDX analysis, phytoferritin, phytin, protein bodies, quinoa, seed structure, seed reserves, starch grains.