Seed structure in Canavalia brasiliensis Mart. ex Benth. (Leguminosae) and subcellular localization of ConBr lectin: implications for ConBr biological functions

Abstract

Lectins are proteins capable of specific and reversible recognition of carbohydrates without modifying them. Many studies have isolated these molecules from Leguminosae seeds but little attention was given to subcellular localization and biological function of these molecules. Therefore, this work aimed to describe Canavalia brasiliensis seed structure and the subcellular localization of ConBr. In addition, we tested the affinity of anti-ConBr antibody for other lectins. To accomplish this, seed fragments were processed for light, scanning and transmission electron microscopy, as well as immunocytochemistry. The anti-ConBr affinity was also tested. Under SEM, the testa showed a regular contour of anticlinal walls without trichomes and inner integument of 10–20 cell layers. The cotyledons presented many parenchymatic cell layers with starch grains and cytoplasmic protein bodies. The immunological identity of anti-ConBr immunoglobulin to ConBr and other lectins was confirmed by immunodiffusion and Western blotting. Ultrastructurally, the cotyledons showed protein bodies characterized by heterogeneous appearance of irregularly formed electron-dense and electron-lucent areas. Immunolocalization showed lectin at both protein bodies and cell wall, however, more studies are required for the elucidation of ConBr functions. Moreover, the affinity of anti-ConBr for different lectins can make this molecule a useful biotechnological tool for lectin studies.