Elemental Analysis and Microscopical Studies of the Mature Seeds of Eleven Species of Pinus

Abstract

The storage reserves in the mature seeds of eleven species of Pinus were investigated. Lipids and proteins 1 sequestered in lipid vesicles and protein bodies respectively 1 were found to be the major storage reserves of pine seeds. All seed tissues of mature Pinus seeds contained protein bodies with one or more protein crystalloids andjor one or more globoid crystals. Energy dispersive x-ray (EDX) analysis of globoid crystals in all species of Pinus that were studied revealed the presence of P 1 K and Mg 1 a fact that is consistent with globoid crystals being phytate-rich. Traces of Ca and Fe were also detected in the globoid crystals of some seed tissues. High levels of Fe and significant levels of P1 K and Mg were detected in small (often .:::; 0. 3 3 J,£m) 1 naturally electron-dense particles that were distributed throughout the tissues of the embryo and female gametophyte. Unlike conventional phytate-rich globoid crystals 1 these Fe-rich particles were not contained in the proteinaceous matrix of typical protein bodies. Instead 1 the particles were contained within membrane-bound structures resembling plastids. Neutron activation analysis and spectrophotometric phosphorus analysis were used to provide a quantitative determination of elements in whole female gametophyte and embryo tissue samples. High levels of P, K, Mg and S and significant levels of Cl, Ca, Mn, Zn and Fe were detected in pine seed tissues. Environment and growth conditions under which the seed developed did not appear to affect the total mineral nutrient levels of mature pine seeds. Seed size and weight varied greatly between the eleven species of Pinus investigated. A major focus of this study was to determine whether seed size was correlated to the distribution of minerals in pine seeds. Previous studies showed that mineral distribution was related to seed size in cucurbits. Phosphorus, Mg and Ca concentrations in globoid crystals and Fe concentrations in electron-dense particles of Pinus seed tissue were found to be negatively correlated with seed size. A comparative study of nutrient reserves in haploid female gametophyte tissue versus diploid embryo tissues was made. Within each species of Pinus, the total mineral nutrient concentrations in whole female gametophyte samples were similar to total mineral nutrient concentrations within whole embryo samples. Protein body structure and the types of mineral nutrients stored in globoid crystals of protein bodies were also similar between female gametophytes and their corresponding embryos.