Studies of Mineral Reserves in Pea (Pisum sativum) Cotyledons Using Low-Water-Content Procedures

Abstract

Most of the phytin in pea (Pisum sativum) cotyledons is water soluble. In order to determine where K and P are located it was necessary to use anhydrous or low water content tissue preparation procedures to obtain samples suitable for energy dispersive X-ray analysis studies using a transmission electron microscope. While some protein bodies do contain electron-dense globoid crystals, most do not. Globoid crystals are more prevalent in the abaxial part of the cotyledon where the provascular network is located. When present, globoid crystals contain considerable Mg, and/or Ca along with P and K. Protein bodies that lack globoid crystals still contain considerable P and K with lesser amounts of elements such as S, Cl and Mg. This is consistent with these protein bodies containing K-phytate in the proteinaceous matrix. While there is a lot of K inside the protein bodies, K is widespread in pea cotyledon tissue and could be detected in starch grains, cell walls and the cytoplasmic matrix.