Ultrastructural analysis and immunocytochemical localization of isolectins in Cratylia mollis seeds

Cratylia mollis is a native forage from the semi-arid region of Northeast, State of Pernambuco, Brazil, whose seeds have been considered an important lectin source. Multiple molecular forms of lectins, carbohydrate-binding proteins, have been purified from C. mollis seeds (Cra Iso) allowing several applications of these purified proteins. In this work seeds were processed for ultrastructural analysis and immunocytochemical localization of the two most abundant isolectins, Cra Iso 1 and Cra Iso 3, with glucose/mannose and galactose specificities, respectively. The ultrastructural analysis revealed a typical plant cell: organelles, nucleus and cellular wall were visualized. The localization of isolectins occurred mainly in the amorphous matrix of protein bodies, and in the cellular walls of the embryonic axis. The results showed that the isolectins, which differ in relation to carbohydrate specificity and glycosylation are located in the same cellular compartment suggesting different functions inside the same subcellular organelle. Cra Iso 1 and Cra Iso 3 distribution in the C. mollis seeds was consistent with the subcellular localization of several legume lectins.