Studies of mature seeds of eleven Pinus species differing in seed weight. II. Subcellular structure and localization of elements

Abstract

Seed tissues of 11 species of Pinus, varying greatly in seed weight, all contained protein bodies with one or more protein crystalloids and (or) one or more globoid crystals. Protein body structure and the types of elements stored in globoid crystals of protein bodies were similar between female gametophytes and their embryos. Energy dispersive X-ray analysis of globoid crystals revealed the presence of P, K, and Mg, a finding consistent with their being phytate rich. Traces of Ca and Fe were also detected in globoid crystals of some tissues. The P and Mg levels in globoid crystals of embryo and female gametophyte tissues decreased as interspecific seed tissue weight increased. High levels of Fe and significant levels of P, K, and Mg were detected in small, often ≤ 0.33 μm, naturally electron-dense particles distributed in all tissues of the embryo and female gametophyte. Unlike conventional phytate-rich globoid crystals, these Fe-rich particles were not contained in typical protein bodies but were contained within membrane-bound structures that may be plastids. Iron levels of the Fe-rich particles of Pinus seed tissues decreased as seed tissue weight increased. Key words: Pinus, seed weight, energy dispersive X-ray analysis, globoid crystals, Fe-rich particles.